Management of white rot (Sclerotium cepivorum) of garlic using fungicides in Ethiopia

Four field experiments were conducted at the Debre Zeit and Bakelo areas of North Shewa, Ethiopia in 2003/2004 and 2004/2005 to determine the effects of five fungicides on epidemics of white rot (Sclerotium cepivorum), and to identify effective fungicides for its management. Five fungicides: tebuconazole as a clove treatment and supplemented basal spray, benomyl, mancozeb, captan and thiram as a clove treatment were applied to Tseday (G-493) and local garlic cultivars. The treatments were arranged in a randomized complete block design with three replications. There was an untreated control for each cultivar. The trials were conducted in fields naturally infested with S. cepivorum. Treatment of garlic cloves with tebuconazole at the rate of 2.1 ml kg−1and spray at 0.25 l ha−1 at stem bases resulted in a significant reduction in initial and final white rot incidence, progress rate, and severity on bulbs. Captan at the rate of 4.17 g kg−1and benomyl at 5.2 g kg−1gave a significant reduction in final disease incidence and the disease was reduced by 16% and 24%, respectively, over the control at Bakelo. At Debre Zeit these fungicides decreased final disease incidence by 40–44%. The highest increase in marketable yield was obtained from garlic treated with tebuconazole (43–73%), captan (48–77%) and benomyl (42–64%) more than the control. Thiram reduced the disease initially, but subsequently did not prove effective. Garlic yield of both cultivars were improved by fungicide application. On average marketable yield increased 27–44.1% at Debre Zeit and 33–70% at Bakelo over the untreated control plots. Differences existed between seasons and locations and these could be due to differences in environment and inoculum levels.