Epidemic development and management of common leaf rust (Puccinia sorghi Schwein) and turcicum leaf blight [Exserohilum turcicum (Pass.)] of maize (Zea mays L.) in eastern Ethiopia

Abstract

Abstract Maize production and productivity are affected by biotic and abiotic factors. Among the biotic factors, fungal diseases incited by common leaf rust (CLR) and turciccum leaf blight (TLB) are the most important foliar diseases of the crop in Ethiopia. A field experiment was conducted at Haramaya University, research station “Raare,” during the 2019/2020 main cropping season. The objectives of the study were to investigate the effect of host resistance and fungicide application on the epidemic development of CLR and TLB, yield and yield components of maize, and the management of these foliar diseases. Four maize varieties (Afranqalloo, Bate, Gibee‐3, and Raare‐1) and Mancozeb at four different rates (0, 1.5, 3.0, and 4.5 kg ha−1) were evaluated under field conditions against the diseases. The treatments were laid out in a factorial arrangement in a randomized complete block design with three replications. All disease and agronomic data were collected during the experimental season. The results from analysis of variance showed that the combination of the variety Bate with Mancozeb at a rate of 4.5 kg ha−1 proved to be the best treatment combination for managing both diseases. Similarly, Mancozeb at a rate of 4.5 kg ha−1 resulted in the lowest CLR and TLB disease incidence and severity (60.4% and 21.0%; 63.7% and 41.78%), respectively. Likewise, the highest grain yield (8392 kg ha−1) and thousand kernel weights of 529 g and the lowest epidemic development were recorded from the variety Bate treated with 4.5 kg ha−1 Mancozeb. The result also revealed that the integration of host resistance (the variety Bate) with 4.5 kg ha−1 Mancozeb was the most effective treatment in reducing CLR and TLB epidemic development and in increasing the grain yield of maize. The economic analysis also showed the presence of the highest marginal rate of return from the Bate variety treated with 4.5 kg ha−1 Mancozeb compared to other treatment combinations. Thus, it is concluded that the variety Bate treated with 4.5 kg ha−1 Mancozeb can be used to improve maize production and productivity in the study area and elsewhere with similar agroecologies.