Powdery mildew is a fungus affecting multiple plant varieties, including green gram. It is caused by the fungus Erysiphe polygoni and can affect plants at any developmental stage. Symptoms of powdery mildew on green grams include white powdery spots on the leaves, stems, and legumes, stunted growth, and decreased yield. The fungus that causes powdery mildew spreads by releasing spores transported by wind, water, or insects.
The disease thrives in warm, humid conditions and can swiftly spread in crowded or poorly ventilated-fields. Managing powdery mildew on green gram includes cultural, chemical, and biological measures. Planting resistant varieties, maintaining proper plant spacing, and avoiding overhead irrigation are examples of cultural practices. At the first evidence of disease, fungicides such as sulfur, triadimefon, or tebuconazole are used for chemical control.
Utilizing natural enemies, such as predatory mites, that prey on the powdery mildew fungus constitutes biological control. Controlling powdery mildew in green gram requires early detection and prompt management. Regular crop monitoring, the use of disease-resistant varieties, and the implementation of appropriate cultural practices can reduce the severity of the disease and increase crop yields.
Powdery Mildew Management in Green Gram/Mung Bean
The Causal Organisms of Powdery Mildew Disease
Powdery mildew disease in green gram is caused by a fungus called Erysiphe polygoni. This fungus grows on the surface of leaves and sends haustoria into the plant’s epidermal cells. It produces conidiophores that bear conidia in short chains. These conidia are hyaline, thin-walled, and single-celled. As the season progresses, black, globose structures called cleistothecia to appear, each containing 4-8 asci. Each ascus contains 3-8 ascospores, which are elliptical and hyaline.
The Disease Cycle of Powdery Mildew Disease
The powdery mildew disease cycle in green gram begins with the fungus overwintering as cleistothecia in infected plant debris. In the spring, ascospores are released from the cleistothecia, which can cause primary infections in healthy plants. The fungus then produces air-borne conidia, which can spread the disease to other plants. Rain splash can also contribute to the spread of the disease by carrying conidia from infected plants to healthy ones. The fungus is an obligate parasite, which means it cannot survive without a host plant.
Causes/Conditions Favorable for Powdery Mildew Disease in the Field
Cool, wet weather favors green gram powdery mold. The disease thrives at 10–20 oC. The fungi also thrive in 90% humidity. The fungi survive and infect healthy plants, causing powdery mildew. The disease spreads in crowded or poorly