PROF. NDERITU JOHN HURIA

EFFICACY OF POTASSIUM SALTS OF FATTY ACIDS IN THE MANAGEMENT OF THRIPS AND WHITEFLIES ON SNAP BEANS
G. O. Wafula*, J. W. Muthomi, J. H. Nderitu and G. N. Chemining’wa
Department of Plant Science and Crop Protection,University of Nairobi. P. O Box 29053-00625 Kangemi, Nairobi, Kenya
Email: ongoya@gmail.com, Tel. 0723144690
Abstract
Snap bean farmers mainly rely on chemical pesticides to manage insect pests and diseases but the introduction of strict maximum residue levels (MRLs) by European markets pose a challenge to the use of pesticides. This has necessitated the search for alternative pest management options that do harmful residues on produce. Therefore, this study was carried out to determine the efficacy of potassium salts of fatty acids as alternative to synthetic chemicals in the management of snap bean pests. Field experiments were carried out in farmers’ fields in Mwea and Embu in 2013 for two cropping cycles. Potassium salts of fatty acids at 0.5%, 1% and 1.5% spray solution were applied weekly starting from three weeks after emergence (WAE) until early podding. The efficacy of the different concentrations was evaluated by assessing population of thrips, whitefly, and pest damaged pods, in addition to pod yield.. The application of potassium salts of fatty acids at 1% and 1.5% of spray solution significantly (P<0.05) reduced white fly and thrips populations by up to 61% and 69% respectively. Pod damage due to thrips was also significantly (P<0.05) reduced by up to 83% and marketable pod yield was significantly (P<0.05) increased by up to 151%. The results demonstrated that potassium salts of fatty acids are a viable alternative to synthetic chemical pesticides thereby enabling farmers to meet the strict European markets maximum residue level requirements.

Key words: Phaseolus vulgaris L., potassium salts of fatty acids, pesticide residues, market access

PEST MANAGEMENT PRACTICES AND COMPLIANCE TO MARKET STANDARDS AMONG FRENCH BEAN FARMERS

Bernard Ouma, James Muthomi, John Nderitu2 and Faith Toroitich
Department of Plant Science and Crop Protection, University of Nairobi, P. O. Box 30197-00100, Nairobi, Kenya
2. Mount Kenya University, P. O. Box 342-01000, Thika, Kenya
Abstract
The EU commission increased to 10% sampling and pesticide residue analysis of French beans and peas imported from Kenya. This resulted in a 25% dip in bean sales in January 2013. This study aimed at determining pest management strategies used by small scale French bean farmers. A survey to determine farmers’ pest management practices was done in Embu east and Mwea east district, where 32 and 38 farmers were from Embu east and Mwea east, respectively. The farmers considered French beans farming as an important source of income, and up to 50% of the farmers had been in French beans production for a period of three years and more. Most of farmers in the study area entirely relied on synthetic pesticides for pest and disease control. White fly was the major insect pest while rust was the major disease as identified by the majority of farmers. Less than 30% of the farmers were involved in the implementation of GLOBALGAP, with 3.1% of the farmers being certified. The findings showed that farmer’s pest management practices were incompatible with good agricultural practices and export market standards. There is a need to sensitize farmers on the use of alternative pest management strategies and requirements of the export market standards.
Key words: French beans, export market requirements, maximum residue levels, Global G.A.P

MANAGEMENT OF SNAP BEAN PESTS BY INTEGRATING SEED DRESSING, FOLIAR SPRAYS AND INTERCROPPING WITH MAIZE
G. O. Wafula*, J. W. Muthomi, J. H. Nderitu2 and G. N. Chemining’wa
Department of Plant Science and Crop Protection,University of Nairobi. P. O Box 29053-00625 Kangemi, Nairobi, Kenya
2. Mount Kenya University, P. O. Box 342-01000, Thika, Kenya
Email: ongoya@gmail.com, Tel. 0723144690
Abstract
Insect pests remain a major constratint in the production of snap beans and farmers mainly rely on chemical pesticides to manage the insect pests and diseases. However, the introduction of maximum residue levels (MRLs) for export vegetables by European markets pose a challenge to the use of pesticides. This study was carried out to develop sustainable options of managing snap bean pests and reducing chemical residues on snap bean produce.
Field experiments were carried out in farmers’ fields in Mwea and Embu from July 2013 to January 2014 for two planting cycles under irrigation. The integrated pest management strategies evaluated included: i) seed dressing only, ii) seed dressing followed by three neem sprays, iii) seed dressing followed by two pyrethrid sprays and one neem spray, iv) seed dressing followed by three pyrethrin sprays and intercropping snap bean with maize, v) seed dressing followed by two pyrethrin sprays plus one spray with a biological product, vi) seed dressing followed by two neem sprays plus one spray with a biological product, and vii) two pyrethrin sprays and one neem spray only. The data collected included: emergence, plant stand, nodulation, thrips population, bean stem maggot population, whitefly population, yield and pest damage. The combination of seed dressing, two pyrethrin sprays and neem applied at the vegetative stage, early flowering and early podding reduced white fly and thrips population by up to 54% and 60% respectively. Similar results were also observed on plots where seeds dressing was done before planting combined with intercropping with maize plus three pyrethrin sprays at the vegetative stage, early flowering and early podding. Seed dressing had a direct effect on the bean stem maggots that attack the seedling at a very young stage. Spraying with pyrethrin sprays had a quick knockdown effect on the population of whitefly and thrips while the maize intercrop also reduced the pest population. These options also reduced pod damage due to thrips by up to 75 and 93% and increased yield of extra-fine by up to 157 and 162% and fine pods by up to 148 and 133%. The results showed that seed dressing followed by two pesthrin sprays at the vegetative stage and early flowering stage plus a single spray with Nimbecidine at early podding, sprays and intercropping with maize were effective in managing snap bean pests. This demonstrates that integrated pest management options would be viable alternatives to chemical pesticides thereby enabling farmers meet the strict maximum chemical residue level requirements set by European consumers.

Key words: Phaseolus vulgaris L, seed dressing, bio-pesticides, intercropping, integrated pest management

Field experiments were conducted over two croppi ng seasons to investigate the effectiveness of border crops in managing potato aphids and the associated viruses in seed potato production. Potato plots were surrounded with maize, sorghum and wheat borde rs. Aphid population was monitored on leaves and on yellow sticky traps. Other data collected included virus disease incidence and tuber yield. The border crops reduced aphid popula tion on leaves compared to non-bordered potato plots. More alate aphids we re caught on yellow sticky traps placed inside potato plots than on traps placed inside the border crops. In addition, virus disease incidence was reduced in all plots surrounded by the border cr ops. However, plots surrounded by border crops had reduced tuber yield, although the yield of s eed grade was increased. The results indicated that use of border crops would be beneficial in the management of virus diseases in small-holder seed potato production.

Potatoes (Solanum tuberosum L.) are second in importance after maize in Kenya as food crop. It is grown mainly by small scale farmers in more than 100,000 ha country wide producing more than 1 million tonnes annually. The marketing value chain has been described as ineffective, with farmers getting far much lesser compared with other players. Recognizing this, the Government of Kenya developed laws in 2005 to streamline the chain and ensure farmers gain from the potato production. It also established some specific laws in 2008 to interpret the 2005 laws in target chain levels. This study was carried out between December 2009 and February 2010 to monitor implementation, enforcement and economic impact of legal notice no. 113 of 2008 of the Government of Kenya using formal questionnaires administered to traders and farmers in selected seven markets and regions. Information was also obtained from focused group discussions as well as stakeholder participation in a workshop. The findings show that traders and farmers are aware of the regulations but are not implementing them. Farmers had higher (97%) knowledge of regulations compared with traders (92%). The major reasons cited by farmers for not being able to implement the regulations included cartels, lack of storage facilities and information about the potato production costs and prevailing market prices at any given time. Calculations show that the contribution of potatoes to the Kenyan economy is 300% higher than what is in government records. This study provides more evidence of the effect of the legal notice on the potato marketing value chain in Kenya and policy recommendations to ensure enforcement of the regulations and streamline the potato value chain.