Practices in using pesticides in urban agriculture: A case of vegetable sector in Dar es Salaam

MSc. Dissertation 2018Urban Agriculture is crucial to the supply of food especially fresh vegetables in many urban areas including Dar es Salaam in Tanzania. In addition to the supply of food, it serves as a source of employment and income for many urban dwellers. However, the intensive and continued growing of vegetable on same piece of the land tend to trigger enormous pests pressure of diverse species which calls for the most effective and robust pest management practices. As such, most urban growers resort to the use wide range of pesticides in controlling the pests. Kinondoni district in Dar es Salaam, Tanzania was used as a case study to explore the pest problems which farmers face, the pest management practices commonly used and the attitudes of urban farmers towards the use of pesticide. A total of 120 farmers were randomly selected through purposive sampling techniques for data collection. Surveys through structured questionnaires focused on respondents’ bio-data, their knowledge on crops and pests problems as well as the management options they employed. The position of pesticides among the commonly used pest management methods which extended to determination of the commonly used insecticides, accessibility and perceived efficacies were also explored. The use of chemical pesticides was found to be the most preferred (68.3%) means by farmers in controlling pests in urban agriculture while cultural and physical control were less common. Farmers expressed confidence in using pesticides due to their effectiveness and easiness to apply. Although highly preferred, some farmers lamented of the limited effectiveness of some pesticides used particularly the insecticides (31.7%). About 30.8% of insecticides used by farmers in Kinondoni district were supplied by private agro dealers in locally available shops while 35.8% were sourced from distant shops away from the farms. Some farmers were aware of other pest control strategies such as Integrated Pest Management (IPM), but lacked in-depth knowledge on the use and iii application of the strategy. Three most commonly used insecticides identified by growers were experimentally tested in the field at Malolo Agricultural Center in Kinondoni for their effectiveness. The insecticides tested were Cypermethrin 10% + Chlorpyrifos 35% at the rate of 2 ml/l of water ; Imidacloprid 200 g/l at the rate of 1 ml/l of water; Lambdacyhalothrin 50 g/l at the rate of 2.5 ml/l of water and (Untreated Control). Insect pests against which the insecticides were tested were Diamondback moth, Plutella xylostella on Chinese cabbage, and Hairy caterpillars, Yellow Bear caterpillar (Spilosoma viginica), Fall webworm (Hyphantria cunea), Bihar caterpillars (Spilosoma obliqua) and Tiger moth caterpillar (Eurocentric vertebrocentrism) in eggplant. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications and four treatments applied at three week interval. The Field test showed that all insecticides were effective against targeted insect pests provided the proper dosage was applied at the right time and appropriate pests threshold. Pyrethroids such as cypermethrin when used in combination with organophosphates effectively controlled both diamondback moth and hairy caterpillars but when pyrethroid was used singly, the effectiveness was compromised particularly on diamondback moth. The findings in this study resolved the long – standing doubt on efficacy of insecticides traded for vegetable production in Kinondoni district. Thus the need for education on appropriate pesticide application technology to vegetable growers cannot be over emphasized