Assessing the effectiveness of thiamethoxam+ lambda cyhalothrin against key insect pests of cowpea (vigna. Unguiculata)

Abstract

In Uganda, cowpea is a major legume grown especially in the east and northern parts. It’s used for food for humans as grain sauce or young leaves eaten as vegetable. It’s used for feeding livestock as a legume fodder and it being very tolerant to harsh climatic conditions, high temperatures. Cowpea is intercropped in fields for nitrogen fixation improving and maintaining soil fertility in these areas. Cowpea production in Uganda is however affected by lots of challenges especially attack by insect pests in the fields hence lowering its attainable yield to very low values. This has led to low production and hunger. Cowpea is attacked by various insect pests at all stages of growth from seedling stage to harvest stage and as an important crop, fast action is imperative to effectively control and manage the attacks and effect of these insect pests. The objective of this study is to evaluate the effectiveness of the insecticide combo thiamethoxam+ lambda cyhalothrin (Aragon) in the control and management of major insect pests in cowpea fields in Uganda. During the first growing season, 3 different application rates were evaluated alongside a positive check (orizon) and the negative check (no insecticide application) each with three replications under completely randomized design at Makerere Agricultural Research station (MUARIK). The chemical was applied after every 10 days from emergence and data collected after every three days from insecticide application. Data collected included plant parameters like plant height, leaf length, width and area, number of leaves in all the plots and Phyto-toxicity of the insecticide. Insect parameters such as number of visible insects on a scale for example aphids (0-9), leaf damages on the scale of 0-5, pods bored and number of natural enemies. Data was also taken on the yields of each plot measuring the grain yield and biomass of each harvest in all different plots at the end of the season. All the different rates of insecticide chemical and positive check (orizon) performed better in reducing the severity and incidence of insect pests in cowpea field than the untreated negative control of the field which was severely attacked by the insect pests almost leaving no yield at all. Using lower rate (1.5mls/5litres of water) showed low yields. Higher rate (2.5mls/5litres of water) showed higher yields, recommended rate (2mls/5litres of water) gave the highest yields, positive check (orizon) gave high yields, and negative control gave the lowest