Effect of Nitrogen and Fungicidal Spray Rates on Incidence and Severity of Garlic Rust (Puccinia allii) at Haramaya, Ethiopia

Abstract

Garlic is one of the most important crops in eastern Ethiopia. The production of the crop is threatened by a number of biotic and abiotic factors. Garlic rust, caused by Puccinia allii, is one of the most important biotic constraints in the area. A field experiment was conducted to determine the effect of nitrogen fertilizer and propiconazole fungicide spray rates on incidence and severity of garlic rust on the variety ‘Tsedey’ under natural condition at Haramaya University experimental site in 2013 main cropping season. The experiment was conducted using four levels of N fertilizer (0, 46, 69, and 92 kg ha^-1) and four different rates of propiconazole (0, 187.5, 250, and 312.5 g a.i ha ^-1). Propiconazole was sprayed at an interval of 10 days. The experiment was laid out as RCBD in a factorial arrangement with three replications. The fungicide treatments resulted in different levels of disease severity on the variety used. The upper two rates of propiconazole were significantly (p ≤ 0.01) effective in reducing levels of incidence and severity of garlic rust. There was generally no significant difference between applications of both rates of propiconazole. Each of the three rates of N fertilizer affected disease levels. Disease severity of up to 80% was recorded in unsprayed plots. Since the data were generated from one season experiment, it is desirable if the experiment is repeated for one more year to generate reliable and conclusive data to use the results in sustainable, environment friendly and effective integrated garlic rust management strategies and thereby stabilizing garlic production in Ethiopia.

Keywords: AUDPC, disease incidence, disease severity, Puccina allii, propiconazole.