Ascochyta leaf spot of wheat: Disease profile and management

Abstract

Wheat (Triticum aestivum L.), which belongs to the order Poales and Family Poaceae, is one of the most important strategic cereal crops around the world. There are many fungal diseases that may occur with this crop. Ascochyta leaf spot is one of the important foliar diseases of wheat. It was found that Ascochyta tritici (Teleomorph: Didymellaexitialis) among many pathogens, is the main causal agent of this disease. The disease becomes severe when the weather is rainy and high humidity conditions. The disease symptoms were represented by occurring oval spots, sometimes elongated, light-colored, and surrounded by a brown margin, then generated white necroses with a very dark brown-black border. Sometimes, symptoms are like those caused by Septoria nodorum. Symptoms are often seen on lower leaves early in the season and on upper leaves later on, so they become less distinct with time, appearing very similar to those caused by S. nodorum. The disease can be controlled by using healthy seeds treated with fungicides, applying crop rotation, conventional tillage, good aeration between plants, balanced fertilization, using plant extracts, and applying many foliar fungicides. Moreover, different bioagents including Trichoderma spp., Pseudomonas fluorescens, and Bacillus spp. have been used to control Ascochyta leaf spot disease biologically and reduce the disease severity significantly. This review summarizes the current knowledge of symptoms and signs, epidemiology, ecology, disease development, disease cycle, and disease management.