PROF. MWANGOMBE AGNES W.

La dégradation du sol constitue un problème majeur dans les zones semi-arides d'Afrique subsaharienne. La lutte contre cette dégradation du sol est capitale pour garantir une productivité durable et à long terme des terres semi-arides habitées. Le Cenchrus ciliaris (vulpin des prés africains), l'Enteropogon macrostachyus (seigle sauvage) et l'Eragrostis superba (Eragrostis Maasai) sont d'importantes graminées vivaces dans les zones semi-arides d'Afrique de l'Est. Une étude a été faite pour évaluer la contribution de ces herbages graminacées indigènes à l'amélioration des propriétés hydrologiques du sol, la réhabilitation, la sécurité alimentaire et les moyens de subsistance des communautés agro-pastorales dans les districts semi-arides du Kenya. Les propriétés hydrologiques du sol ont été testées à l'aide d'un simulateur Kamphorst, à diverses hauteurs de chaume, pour donner une image de trois différentes intensités de pâturage (faible, moyenne, élevée). L'estimation de la couverture végétale s'est faite à l'aide de la méthode d'échantillonnage step-point. Une étude a également été réalisée dans 50 ménages agro-pastoraux pour évaluer les avantages multidimensionnels des herbages graminacées. La production de sédiments (comme fonction d'écoulement et capacité d'infiltration) était considérablement différente (P<0,05) à diverses hauteurs de chaume. Les estimations de la couverture végétale des herbages graminacées étaient également considérablement différentes (P<0,05). Le Cenchrus ciliaris avait le plus grand impact en matière d'amélioration des propriétés hydrologiques. L'Enteropogon macrostachyus et l'E. superba se classaient respectivement en deuxième et troisième positions. L'Enteropogon macrostachyus avait la plus grande couverture. Le Cenchrus ciliaris et l'E. superba se classaient respectivement en deuxième et troisième positions. Ces résultats étaient dus à la croissance et aux caractères morphologiques des herbages graminacées. En général, une augmentation de la hauteur de chaume augmente la capacité d'infiltration et réduit l'écoulement et la formation de sédiments. Les résultats de l'enquête réalisée auprès des ménages révèlent que les herbages graminacées constituent une source de revenus par le biais de la vente de foin, de graines de graminacées et de lait, ce qui participe également d'un régime équilibré. Les herbages graminacées constituent également une source bon marché de matériel pour la confection de toitures de chaume et d'aliments pour le bétail. (Résumé d'auteur)

Land degradation is a major problem in the semi-arid environments of Sub-Saharan Africa. Fighting land degradation is essential to ensure the sustainable and long-term productivity of the habited semiarid lands. In Kenya, grass reseeding technology has been used to combat land degradation. However, despite the use of locally adapted perennial grass species namely Cenchrus ciliaris (African foxtail grass), Eragrostis superba (Maasai love grass) and Enteropogon macrostachyus (Bush rye) failure still abound. Therefore, more land is still being degraded. The aim of this study was to determine the main factors which contribute to failures in rehabilitating denuded patches in semi-arid lands of Kenya. A questionnaire was administered to capture farmer perceptions on failures on rangeland rehabilitation using grass reseeding technology. Rainfall data was collected during the study period. Moreover, rehabilitation trials using the three grasses were done under natural rainfall. Results from this study show that climatic factors mainly low amounts of rainfall to be the main contributor to rehabilitation failures. 92% of the respondents asserted that reseeding fails because of low rainfall amounts received in the area. The study area received a total of 324 mm of rainfall which was low compared to the average annual mean of 600mm. Reseeded trial plots also failed to establish due to the low amounts of rainfall received. This showed how low rainfall is unreliable for reseeding. Other factors namely destruction by the grazing animals, pests and rodents, flush floods, poor sowing time, poor seed quality, lack of enough seed and weeds also contribute to rehabilitation failures in semi-arid lands of Kenya.

Kent papers in POlitics and International Relations, Series 4, No. 4.

Kent papers in POlitics and International Relations, Series 4, No. 4.

Land degradation is a major problem in the semi-arid environments of Sub-Saharan Africa. Fighting land degradation is essential to ensure the sustainable and long-term productivity of the habited semiarid lands. In Kenya, grass reseeding technology has been used to combat land degradation. However, despite the use of locally adapted perennial grass species namely Cenchrus ciliaris (African foxtail grass), Eragrostis superba (Maasai love grass) and Enteropogon macrostachyus (Bush rye) failure still abound. Therefore, more land is still being degraded. The aim of this study was to determine the main factors which contribute to failures in rehabilitating denuded patches in semi-arid lands of Kenya. A questionnaire was administered to capture farmer perceptions on failures on rangeland rehabilitation using grass reseeding technology. Rainfall data was collected during the study period. Moreover, rehabilitation trials using the three grasses were done under natural rainfall. Results from this study show that climatic factors mainly low amounts of rainfall to be the main contributor to rehabilitation failures. 92% of the respondents asserted that reseeding fails because of low rainfall amounts received in the area. The study area received a total of 324 mm of rainfall which was low compared to the average annual mean of 600mm. Reseeded trial plots also failed to establish due to the low amounts of rainfall received. This showed how low rainfall is unreliable for reseeding. Other factors namely destruction by the grazing animals, pests and rodents, flush floods, poor sowing time, poor seed quality, lack of enough seed and weeds also contribute to rehabilitation failures in semi-arid lands of Kenya.

Participatory rural appraisal techniques and a survey of 100 households were used to evaluate livestock production, and pastoral development of the Maasai in Mara. It was observed that patterns of land-use have principally changed from nomadic pastoralism to sedentary pastoralism, agropastoralism, and, in some cases, pure cultivation. These trends have adversely affected livestock production and the productive capacity of the Mara ecosystem. Diminishing grazing area occasioned by expanding cropping patterns has negatively impacted on vegetation resources and the biodiversity of the ecosystem. It has also increased the intensity of conflict over diminishing land resources. Because the production system is largely subsistence with a strong livestock base, it is further undermined by, among other factors, animal diseases, water scarcity, land individualisation, poor marketing infrastructure, and livestock/wildlife conflicts. Based on the findings of the present study, development approaches need to emphasize integrated livestock and wildlife utilization, land tenure reforms that embody livestock mobility as a key strategy of optimising the use of transient forage resources, disease control, and development of livestock marketing.

Fusarium solani (Mart) f.sp. phaseoli (Burk) Synd. and Hans., is a plant pathogeniC fungus that causes root rot in garden bean (Phaseo/us vulgaris L.). To evaluate methods used in classifying strains of this pathogen, 52 Fusarium solani f.sp. phaseoli isolates from infected bean plants grown on different farms in Taita hills of Coast province, Kenya, were cultured and characterized using morphology, pathogenicity and microsatellite DNA. All the isolates showed high variability in aerial mycelial growth, mycelia texture, pigmentation (mycelia colour) when cultured on potato dextrose agar medium, and conidial measurements on Spezieller Nahrstoffarmer agar medium. Colonies were grouped into luxuriant, moderately luxuriant and scanty on aerial mycelial growth; fluffy and fibrous based on mycelial texture; purple, pink and white based on mycelia colour; and long, medium and short macroconidiallength. All the isolates were pathogenic on GLP-2 (Rosecoco), a susceptible bean variety commonly grown in Kenya. DNA analysis showed that the isolates carried a high genetic diversity (gene diversity = 0.686; mean number of alleles = 9). Neighbour-Joining phylogenetic clusters reconstructed using microsatellite variation showed three major clusters. However, the microsatellite groupings were independent of the altitude, colony characteristics and virulence of the isolates.

Open and distance learning (ODL) in Kenya, like in many other developing countries, is characterized by, and offered through, dual mode institutions. Most of these programmes are in humanities and social sciences. Currently, one private university is offering agricultural training at a distance using print medium. A few private organizations or NGOs carry out short duration informal agricultural capacity building programmes to farmer groups an d extension workers using technology- mediated open and distance education (Tech-MODE). The Government of Kenya placed emphasis on education and training in agriculture, because of the important role it plays in the country’s economy. Although great potential exists for the use of Tech-MOD E in agricultural sciences at primary, secondary, tertiary and informal levels in Kenya, its application still largely remains untapped. However, with the recent completion of the National ICT Policy (2006), the Ministry of Education, in consul tation with stakeholders, developed a comprehensive National ICT Strategy for education and training, with a view to guiding the implementation of informat ion and communication technology (ICT) initiatives in the education sector. This country report highlights the existing potential in Kenya that the project on Tech-MODE for agricultural education prop osed by the Commonwealth of Learning (COL) could build on. It is suggested that consideration should be given to strengthening relations with the existing national, regional and international institutions and networks or programmes . Priority areas for training should be identified by all participating stakeholde rs for support in content development and institutional capacity building. This initiative offers opportunities for mu lti-institutional part nerships to prepare training content that would not only provid e locally relevant and practical knowledge, but also would be internationally recogniz ed. Tech-MODE for agricultural education would offer viable alternatives by lowering education costs, increasing professional retention and not taking trainees out of their professional roles and homes for extended periods. In addition, benefici aries would contribute to increased and sustainable agricultural production, develo pment in the country, poverty reduction and improved food security

Participatory rural appraisal techniques and a survey of 100 households were used to evaluate livestock production, and pastoral development of the Maasai in Mara. It was observed that patterns of land-use have principally changed from nomadic pastoralism to sedentary pastoralism, agropastoralism, and, in some cases, pure cultivation. These trends have adversely affected livestock production and the productive capacity of the Mara ecosystem. Diminishing grazing area occasioned by expanding cropping patterns has negatively impacted on vegetation resources and the biodiversity of the ecosystem. It has also increased the intensity of conflict over diminishing land resources. Because the production system is largely subsistence with a strong livestock base, it is further undermined by, among other factors, animal diseases, water scarcity, land individualisation, poor marketing infrastructure, and livestock/wildlife conflicts. Based on the findings of the present study, development approaches need to emphasize integrated livestock and wildlife utilization, land tenure reforms that embody livestock mobility as a key strategy of optimising the use of transient forage resources, disease control, and development of livestock marketing.

Participatory rural appraisal techniques and a survey of 100 households were used to evaluate livestock production, and pastoral development of the Maasai in Mara. It was observed that patterns of land-use have principally changed from nomadic pastoralism to sedentary pastoralism, agropastoralism, and, in some cases, pure cultivation. These trends have adversely affected livestock production and the productive capacity of the Mara ecosystem. Diminishing grazing area occasioned by expanding cropping patterns has negatively impacted on vegetation resources and the biodiversity of the ecosystem. It has also increased the intensity of conflict over diminishing land resources. Because the production system is largely subsistence with a strong livestock base, it is further undermined by, among other factors, animal diseases, water scarcity, land individualisation, poor marketing infrastructure, and livestock/wildlife conflicts. Based on the findings of the present study, development approaches need to emphasize integrated livestock and wildlife utilization, land tenure reforms that embody livestock mobility as a key strategy of optimising the use of transient forage resources, disease control, and development of livestock marketing.

A survey to determine the prevalence, incidence and severity of angular leaf spot of common bean was conducted in Embu, Kakamega, Kiambu, Machakos and Taita Taveta districts of Kenya. The districts were selected based on the intensity of bean production, spatial and ecological location. Angular leaf spot was prevalent in all the districts and was recorded in 89% of the farms visited. The disease was present in all the farms surveyed in Embu, Kakamega and Machakos districts. In Taita Taveta and Kiambu districts, disease prevalence was 80 and 65%, respectively. The disease was prevalent across the lower midland, lower highland and upper midland agroecological zones and altitude ranges of 963-2322 m above sea level (m.a.s.l.). Disease incidence and severity were high (mean values of 49.6 and 21.4%, respectively) and varied significantly (p≤0.05) among districts, farms, agroecological zones and different altitudes. Kakamega and Taita Taveta districts recorded the highest disease incidence and severity, respectively, whereas Embu district had the lowest incidence and severity. Bean fields in the altitude ranges of below 1200 m and 1600-2000 m.a.s.l. had the highest disease severity (33.8%) and incidence (52.9%), respectively, whereas areas above 2000 m recorded lower disease levels. Agroecological zone LM2 and UM4 had the highest levels of disease incidence and severity whereas zones LH1 and UM3 had the lowest levels, respectively. These results indicate that angular leaf spot is severe and highly prevalent in Kenya. The disease spans across all the agroecological zones and altitude ranges where beans are grown. Efforts should, therefore, be geared towards an integrated approach to manage the disease.

Two surveys were carried out in October 2001 (season 1) and April 2002 (season 2) in five divisions of Embu district during the short and long rains, respectively. Ten farms were randomly selected per division and fifteen bean plants were sampled from every farm and used to determine the occurrence and incidence of bean root rot and bean stem maggot. Each bean root was examined for the presence of bean stem maggot and root rot pathogen. The incidences of bean root rot diseases and bean stem maggot were significantly (p = 0.05) higher during the short rain than during the long rains. Wetter agro-ecological zones such as LH2 and UM1 had more incidence of root rot than UM2, UM3 and UM4. During both seasons Fusarium solani, Rhizoctonia solani and Macrophomina phaseolina were the major root rot pathogens isolated. The species of bean stem maggot found in Embu district were Ophyiomia spencerella and O. phaseoli, with the latter being the dominant species. Agro-ecological zones had no significant effect on the incidence of bean stem maggot. Root rot disease was frequently associated with bean stem maggot. Pearson correlation (r) between bean root rot disease and bean stem maggot was 0.495. The result is important in the management of bean root rot and bean stem maggot.

Participatory rural appraisal techniques and a survey of 100 households were used to evaluate livestock production, and pastoral development of the Maasai in Mara. It was observed that patterns of land-use have principally changed from nomadic pastoralism to sedentary pastoralism, agropastoralism, and, in some cases, pure cultivation. These trends have adversely affected livestock production and the productive capacity of the Mara ecosystem. Diminishing grazing area occasioned by expanding cropping patterns has negatively impacted on vegetation resources and the biodiversity of the ecosystem. It has also increased the intensity of conflict over diminishing land resources. Because the production system is largely subsistence with a strong livestock base, it is further undermined by, among other factors, animal diseases, water scarcity, land individualisation, poor marketing infrastructure, and livestock/wildlife conflicts. Based on the findings of the present study, development approaches need to emphasize integrated livestock and wildlife utilization, land tenure reforms that embody livestock mobility as a key strategy of optimising the use of transient forage resources, disease control, and development of livestock marketing.

Participatory rural appraisal techniques and a survey of 100 households were used to evaluate livestock production, and pastoral development of the Maasai in Mara. It was observed that patterns of land-use have principally changed from nomadic pastoralism to sedentary pastoralism, agropastoralism, and, in some cases, pure cultivation. These trends have adversely affected livestock production and the productive capacity of the Mara ecosystem. Diminishing grazing area occasioned by expanding cropping patterns has negatively impacted on vegetation resources and the biodiversity of the ecosystem. It has also increased the intensity of conflict over diminishing land resources. Because the production system is largely subsistence with a strong livestock base, it is further undermined by, among other factors, animal diseases, water scarcity, land individualisation, poor marketing infrastructure, and livestock/wildlife conflicts. Based on the findings of the present study, development approaches need to emphasize integrated livestock and wildlife utilization, land tenure reforms that embody livestock mobility as a key strategy of optimising the use of transient forage resources, disease control, and development of livestock marketing.

Seven hundred and fifty bean plant samples with root rot symptoms were

collected from farmers' fields during two surreys carried out in Embu district,

Kenya. Various fungal pathogens were isolated in the laboratory from these

samples; among them were 50 isolates of Rhizoctonia solani, which were

subjected to pathogenicity tests in a glasshouse. Thirty-six isolates of R. solani

obtained from beans with root rots were subjected to DNA microsatellite analysis.

Five isolates of R. solani that cause black scarf of potatoes (Solanum tuberosum

L.) were also analysed alongside those from the beans. A total of 50 alleles were

detected when six microsatellite loci were typed in the 41 samples, with the mean

of 8.33 and a range of 3 at locus RB23 to 19 at locus AF513014. The smallest

allele size was 129 basepair at locus RE102 and the largest was 297 basepair at

locus AY212027. Microsatellite analysis showed a moderate variation among the

isolates from different agro-ecological zones and administrative boundaries

(divisions). Phylogenetic analysis revealed 3 major clusters within the population

of 41 isolates of R. solani from Kenya. Clusters 1, 2 and 3 had 15, 10 and 75%

isolates, respectively. However, cluster 3 had 4 sub-clusters and cluster 1 had 2

sub-clusters, while cluster 2 did not have a sub-cluster. There was no relationship

between microsatellites and geographical origin of the isolates. This is the first

study on the genetic diversity of R. solani using DNA microsatellite analysis in

Kenya.

Seven hundred and fifty bean plant samples with root rot symptoms were collected from farmers' fields during two surreys carried out in Embu district, Kenya. Various fungal pathogens were isolated in the laboratory from these samples; among them were 50 isolates of Rhizoctonia solani, which were subjected to pathogenicity tests in a glasshouse. Thirty-six isolates of R. solani obtained from beans with root rots were subjected to DNA microsatellite analysis. Five isolates of R. solani that cause black scarf of potatoes (Solanum tuberosum L.) were also analysed alongside those from the beans. A total of 50 alleles were detected when six microsatellite loci were typed in the 41 samples, with the mean of 8.33 and a range of 3 at locus RB23 to 19 at locus AF513014. The smallest allele size was 129 basepair at locus RE102 and the largest was 297 basepair at locus AY212027. Microsatellite analysis showed a moderate variation among the isolates from different agro-ecological zones and administrative boundaries (divisions). Phylogenetic analysis revealed 3 major clusters within the population of 41 isolates of R. solani from Kenya. Clusters 1, 2 and 3 had 15, 10 and 75% isolates, respectively. However, cluster 3 had 4 sub-clusters and cluster 1 had 2 sub-clusters, while cluster 2 did not have a sub-cluster. There was no relationship between microsatellites and geographical origin of the isolates. This is the first study on the genetic diversity of R. solani using DNA microsatellite analysis in Kenya. Key words: DNA microsatellite analysis, Kenya, Phaseolus vulgaris and Rhizoctonia solani

Seven hundred and fifty bean plant samples with root rot symptoms were collected from farmers' fields during two surreys carried out in Embu district, Kenya. Various fungal pathogens were isolated in the laboratory from these samples; among them were 50 isolates of Rhizoctonia solani, which were subjected to pathogenicity tests in a glasshouse. Thirty-six isolates of R. solani obtained from beans with root rots were subjected to DNA microsatellite analysis. Five isolates of R. solani that cause black scarf of potatoes (Solanum tuberosum L.) were also analysed alongside those from the beans. A total of 50 alleles were detected when six microsatellite loci were typed in the 41 samples, with the mean of 8.33 and a range of 3 at locus RB23 to 19 at locus AF513014. The smallest allele size was 129 basepair at locus RE102 and the largest was 297 basepair at locus AY212027. Microsatellite analysis showed a moderate variation among the isolates from different agro-ecological zones and administrative boundaries (divisions). Phylogenetic analysis revealed 3 major clusters within the population of 41 isolates of R. solani from Kenya. Clusters 1, 2 and 3 had 15, 10 and 75% isolates, respectively. However, cluster 3 had 4 sub-clusters and cluster 1 had 2 sub-clusters, while cluster 2 did not have a sub-cluster. There was no relationship between microsatellites and geographical origin of the isolates. This is the first study on the genetic diversity of R. solani using DNA microsatellite analysis in Kenya. Key words: DNA microsatellite analysis, Kenya, Phaseolus vulgaris and Rhizoctonia solani

Thirty-eight isolates of Fusarium udum obtained from pigeonpea (Cajanus cajan) plants showing wilt symptoms were collected from various districts in F. udum isolates by selecting chlorate-resistant sectors on minimal medium amended with 15 g l!  potassium chlorate. All the isolates of F. udum were grouped into a single VCG (VCG 1) with two subgroups VCG 1 I and VCG.l II. The DNA of the fungal isolates was extracted using CT AB method. The AFLP analysis of 38 isolates using seven primer combinations generated a total of:318 fragments with 102 being polymorphic (32.% polymorphism).The isolates could be grouped into one AFLP group with more than ten subgroups based on the analysis of the banding patterns, although most of these subgroups were not significantly distant <50% confidence interval) genetically. Based on VCG and AFLP, the isolates could have originated from a single lineage. The VCG and, AFLP of F. udum were independent of geographical origin of the isolates.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes. Keywords: Angular leaf spot, genetic diversity, Phaeoisariopsis griseola, virulence, Kenya.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

The wide pathogenic variability occurring in phaeoisariopsis griseola, the causal agent of angular leaf spot of common bean (phaseolus vulgaris l.), is the greatest set-back to development and deployment of resistant bean varieties. The high pathogen variability dictates that new sources of resistance be continuously identified. This study was undertaken to evaluate reactions of selected bean germplasm to different races of p. griseola in an effort to identify potential sources of resistance to als. Selected bean lines/varieties from ecabren were separately inoculated with forty-four races of p. griseola and evaluated for disease development under greenhouse conditions. Isolates of p. griseola used in this study were collected from diverse bean growing areas in kenya and characterised into races based on the reactions of 12 differential bean cultivars. None of the varieties was resistant to all the races, indicating a high complexity of the pathogen population. eight varieties were resistant (disease grade 1 to 3) or moderately resistant (grade 4 to 6) to at least 40 (91%) of the races. bean lines ecab 0754 and ecab 0617 exhibited the highest level of resistance and were each susceptible to one race of p. griseola. all the resistant or intermediate resistant varieties were of the small- or medium-seeded bean types, whereas the commonly-grown large seeded varieties were generally susceptible. these results indicate that a number of bean varieties have varying levels of resistance that could be pyramided to provide durable resistance to angular leaf spot.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

A survey of bactenal wilt (BW) incidence was carried out in three potato producing districts of Kenya, namely, Nyeri, Nyandarua, and Meru in 1997. The survey was carried out in 30 randomly selected farms in each district. Incidence of BW was highest (18.8%) in Nyeri district, intermediate (16.7%) in Meru and lowest (10.4%) in . Nyandarua. A significant and negative correlation (p=O.05; r = -0.34) between bacterial wilt incidence and altitude was observed. Fifteen potato cultivars, Nyayo, Desiree CIP-800048, Roslin Tana, Kerrs pinkLB-5, Golof (Dutch Robjin), B53, Tigoni CIP-381381.13, Rutuku CIP-720097, AsanteCIP-381381.20, Kenya DhamanaCIP- 800228, Mauritius Clone (89•016), .: KP93739.26, KP92633.26, and Cruza148 CIP-72011 were subsequently evaluated for their reaction to Ralstonia solanacearum in artificial and natural infections in the greenhouse and in the field. Although none of the cultivars appeared resistant, there were significant (p=0.05) differencesir bacterial wilt incidence and severity among the cultivars. Cultivars Kenya Dhamana, Mauritius and Cruza(Cllt- 720118) had low bacterial wilt severity and incidence and were rated tolerant, whereas the other cultivars were rated moderately susceptible or very susceptible.

A survey was undertaken to determine population density of Meloidogyne juveniles (J2) in 90 fields randomly selected from three potato-producing districts in Kenya namely Nyeri, Meru and Nyandarua. Mean nematode densities were highest (45) in samples collected from Nyeri and Nyandarua and lowest (31) in soil samples collected from Meru. The reaction of 15 potato cultivars to Meloidogyne incognita was determined under greenhouse conditions. Plants were inoculated with 6000 eggs and second-stage juveniles each. Highly significant (P=0.01) differences were observed between the cultivars. Galling index was highest (5.5) in cv. KP93739.26 and lowest (1.9) in cv. Nyayo. All cultivars supported nematode reproduction with the highest (5.0) egg mass index being recorded in cultivars KP93739.26, Kerr's Pink, Desiree CIP-800048, KP92633.26 and B53. No cultivar exhibited immunity. The relationship between infection by root-knot nematodes and severity of bacterial wilt in three potato cultivars with varying levels of resistance to bacterial wilt namely Asante CIP 381381.20 (susceptible), B53 (moderately susceptible), and Kenya Dhamana (resistant), was investigated in a greenhouse experiment. Bacterial wilt was more severe in plants infected with both pathogens as compared to plants infected with Ralstonia solanacearum alone.

In order to assess the status of pigconpca (Cajanus cajon (L.) Millsp.) production in KenY;1, two surveys were carried out in Mac~lIeni and Mhecre Districts in arcus representative or the main agro-ccological pigcoupca producing zone of the country (lfl--"itititude ASAL). Participatory Rural Appraisal (PRA) approach was chosen as research method and was completed by household interviews based on :1 semi-structured questionnaire. The main points developed are the presentation of the different farming systems in which pigconpca is considered as an important legume crop, the identification of the factors explaining pigeon pea production variations, the quantification of the use of improved varieties and improved production practices, and the analysis of the major patterns and trends in pigeonpca production, consumption and marketing. Keywords. Pigeonpca, C(!j(1I7I1S cajun, ri1r111ing systcrn, pnrticipnrory rurul nppraisul, Kenya.

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Genetic diversity of 50 Phaeoisariopsis griseola isolates collected from different agro ecological zones in Kenya were studied using group specific primers and amplified fragment length polymorphism (AFLP) markers. Group-specific primers differentiated the isolates into Andean and Mesoamerican groups, corresponding to the two common-bean gene pools. Significant polymorphisms were observed with all the AFLP primer combinations used, reflecting a wide genetic diversity in the P. griseola population. A total of 207 finger prints was generated, of which 178 were polymorphic. Cluster analysis of the polymorphic bands also separated the isolates into the two groups defined by group specific primers. All the isolates examined were grouped into three virulence populations; Andean, Afro-Andean and Mesoamerican, and their genetic diversity measured. On average, greater diversity (91%) was detected within populations than between populations (9%). The genetic distance between Andean and Mesoamerican populations was higher (D = 0.0269) than between Andean and Afro-Andean (D = 0.0095). The wide genetic diversity reported here has significant implications in breeding for resistance -to angular leaf spot and should be taken into consideration when screening and deploying resistant bean genotypes.

Pathogenicity tests were performed on 11 genotypes of Coffea arabica using single-isolate suspensions of Colletotrichum Kahawae obtained from 90 monoconidial isolates. The objective of this study was to estimate the proportion of pathogenic variation corresponding 10 differences in aggressiveness and virulence (races). A large part of the variation in the pathogen population was due to aggressiveness. The differential effects were too small to suggest conclusively that races exist. This paper discusses the possible causes for the observed small differential interaction and suggests breeding strategies that not only prevent possible adaptation of the pathogen to resistant varieties but also limit variation for resistance due to differences in aggressiveness of the pathogen.

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion

Fusarium wilt caused by Fusarium udum Butler, is an economically important disease of pigeonpea (Cajanus cajan (L.) Mill). Information on the mechanisms of resistance to this disease in pigeonpea is limited. To study the role of vascular occlusion in wilt resistance, isolates of F.udum were inoculated onto resistant and susceptible varieties of pigeonpea and observed under light and transmission electron microscopes. The presence of F. udum in wilt susceptible plants was characterized by mycelia and conidia in the xylem vessels, plugging in some vessels, disintegration of xylem parenchyma cells in the infected areas, and the formation of cavities due to heavy colonization in the pith cortex vascular bundle. Resistance to F. udum in the roots and stems of wilt resistant plants was associated with low fungal colonization and high occlusion due to tyloses and gels in the xylem vessels. There were significant differences (P = 0:05) in the number of xylem vessels occluded by tyloses in resistant and susceptible plants with a maximum of 22.5% and 8.0% occlusion, respectively. It is probable that tyloses and gels formed as a result of F. udum interaction in wilt resistant plants are part of a resistance mechanism. Key words: Fusarium wilt,cajanus cajan, resistance, tylose, vascular occlusion