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

This study evaluated 403 farmers from the open field and greenhouse farms in Mwea Irrigation Scheme on the types and classification of pesticides used to control pests and diseases on tomatoes, in July 2017 to June 2018. Five greenhouse tomato farmers were purposively selected while sample size of 196 open field farmers, calculated using Fisher’s formula. Cross-Sectional design using a structured questionnaire, face to face interviews and focus group discussions with 201 farmers in the eight wards, Gathingiri, Tebere, Kangai, Wamumu, Murinduko, Nyangati, Mutithi and Thiba. Accuracy of the 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 the interviews revealed that farmers applied 57 and 12 pesticides under different trade names on tomatoes in the open field and greenhouse farms respectively. Pyrethroids, carbamates, nicotinoids, organophosphates, and organochlorines were applied on tomatoes among others. The 20 and 12 pesticides mainly used in open field and greenhouse farms 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 as Tuta absoluta and blight respectively. Chlorantraniliprole and mancozeb are the main pesticides used in tomatoes. Most pesticides, WHO toxic class II including pyrethroids and carbamates should be used following manufacturers’ recommendations to prevent human health risks. 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 with minimal negative effects on human  health.