Effect of KENCOP fungicide on the control of angular leaf spot on French beans

Abstract

Uganda is Africa’s second largest bean producer after Tanzania. Production of beans in Uganda is predominantly on a small-scale accounting between 60–90% of the production with average productivity of 0.25 tons (250kg) per acre despite potential yield of 700 to 1500kg/acre. The production potential has been undermined by among other factors insect pests and diseases which are the major biotic constraints. Angular leaf spot (ALS) disease caused by Pseudocercospora griseola (Sacc.) among other diseases is the most important. It causes severe and premature defoliation resulting in shrivelled pods, shrunken seeds and yield losses of up to 80%. It is also reported that every 10% increase in Angular Leafspot severity results in 7.9 % yield loss of beans. It is against this background that a study was conducted in two different agro ecological zones that is BUAC in Soroti district and BugiZARDI, Bulambuli district for two consecutive seasons (2022A and 2022B) to test the efficacy of a new fungicide, KENCOP that has a different active ingredient and mode of action in controlling ALS on French beans. Experiments were set in a randomized complete block design with three replications and five treatments (60g/20l KENCOP, 40g/20 KENCOP, 20g/20l KENCOP, 20g/20l, Cobox (positive control and commonly used fungicide) and untreated plots (negative control)). The treatments were applied thrice i.e. after every two weeks from the sight of the first ALS symptom. The parameters collected to measure the effectiveness of the rates were ALS disease incidence and severity, fresh pod weights, pod numbers and pod length to constitute the yields. The disease parameters were collected after every one week from the first treatment application while the yield parameters were collected at harvest (physiological maturity). KENCOP was very effective in suppressing ALS in both locations and seasons and its effect was comparable to Cobox fungicide. The higher rates of KENCOP (60g/20l and 40g/20l) showed low disease pressures, though high disease occurrence was observed in Bulambuli than Soroti. Similar observations were also made for the yield parameters across the two sites. In conclusion, the experiment showed KENCOP fungicide was effective in controlling ALS in French beans. At a rate of 40g/20l, KENCOP can be used as an alternative fungicide in the management of the ALS. However, in cases of high rainfall intensity, a higher rate of 60g/20l KENCOP is recommended.