Critical Evaluation of Types and Classification of Pesticides Used on Tomatoes Grown in Mwea Irrigation Scheme, Kirinyaga County, Kenya

This study evaluated 403 farmers from the open fields and greenhouses in Mwea Irrigation Scheme on the types and classification of pesticides farmers use to control pests and diseases on tomatoes, in July 2017 to June 2018. Production of enough food to meet consumer demand on quality and quantity are almost impossible without the use of pesticides in developed and developing countries. Five greenhouse tomato farmers were purposively selected while sample size of 196 open field farmers was calculated using Fisher’s formula. Cross-Sectional design that used a structured questionnaire and focus group discussions was used to collect data from 201 farmers in Gathingiri, Tebere, Kangai, Wamumu, Murinduko, Nyangati, Mutithi and Thiba wards. Accuracy of data was ensured by pre-testing the questionnaire on tomato farmers from a neighbouring Maragua sub-county. Errors were corrected and omissions added to the questionnaire. Descriptive statistics was carried out for frequencies, percentages, means, standard errors, variance and data subjected to T-test at 95% Confidence Interval to determine significant differences between variables. Results from interviews revealed that farmers applied 57 and 12 pesticides under different trade names on tomatoes in the open fields and greenhouses respectively. Pyrethroids, carbamates, nicotinoids, organophosphates, and organochlorines were applied on tomatoes among others. The 20 and 12 pesticides mainly used in open fields and greenhouses were WHO Class II (60%) and WHO Class III (42%), respectively. Farmers heavily relied on different types of pesticides to control a wide range of major pests and diseases such as Tuta absoluta and blight respectively. Chlorantraniliprole and mancozeb are the main pesticides used on tomatoes. Most pesticides, WHO toxic class II including pyrethroids and carbamates should be used following the manufacturers’ recommendations to prevent human health risks. Compliance with pesticide use standards will prevent occurrence of residues on tomatoes and other vegetables and thus minimize their effects on human health.  Training and awareness by the Ministry of agriculture, Kirinyanga County government are needed on use of less toxic pesticides equally effective in controlling pests and diseases, such as WHO  classes III and IV and bio-pesticides that have minimal negative effects on human  health.