Powdery mildew is a fungus that infects a wide variety of plants. Many distinct species of ascomycete fungus in the order Erysiphales cause powdery mildew diseases. Powdery mildew is one of the more superficial plant diseases to diagnose due to its distinguishing characteristics. White powdery patches appear on the leaves and stems of infected plants.
The basal leaves are the most afflicted. However, mildew can grow on any section of the plant above ground. As the disease proceeds, the spots become larger and denser as a huge number of asexual spores are produced, and the mildew may move up and down the plant.
Powdery Mildew disease management in Wheat
The causal organism of Powdery Mildew disease
The pathogen responsible for powdery mildew disease in Wheat is Erysiphe graminis tritici, a fungus species belonging to the genus Erysiphe. This fungus produces septate, superficial, hyaline mycelium on the leaf surface, characterized by a network of delicate, branching filaments. The mycelium produces short conidiophores, specialized structures that produce conidia, or reproductive cells. The conidia are elliptical, hyaline, single-celled, thin-walled, and produced in chains.
In addition to conidia, E. graminis tritici also produces cleistothecia, which are dark, globose structures that contain asci. The asci contain 9-30 oblong, hyaline, and thin-walled ascospores, the primary means of reproduction and spread of the fungus. The ascospores can infect new plants, leading to the spread of powdery mildew disease in wheat crops.
Disease cycle of Powdery Mildew disease
Powdery mildew in Wheat is caused by the fungal pathogen Erysiphe graminis tritici, which grows and reproduces. The fungus lives as latent mycelium and asci in infected plant detritus, waiting for ideal circumstances to develop. The fungus may infect young plants with high humidity and moderate temperatures.
Powdery mildew spreads primarily through ascospores, which are formed within cleistothecia. Wind currents carry the ascospores to neighboring plants, where they infect the surface of the leaves, stems, and grain heads. Infected regions may produce white, powdery growths that, over time, will spread and cover huge parts of the plant.
Powdery mildew can spread in the air via airborne conidia generated by the fungus on the surface of diseased plants. The conidia can infect new plants, causing the illness to spread.
Favorable conditions for the spread of Powdery Mildew disease
Powdery mildew thrives in high humidity and cool to moderate temperatures, with optimal temperatures ranging from 20-21°C. High humidity provides the ideal environment for the fungus to grow and infect new plants. At the same time, the cool to moderate temperatures allow the fungus to persist and spread. The disease can infect plants without rain if high humidity and moderate temperatures are present.