How to Control Wheat Powdery Mildew? A Detailed Guide to Practical Methods

Select wheat varieties resistant to powdery mildew, such as Zhengzhou 8915, Zhongyu 4 and Yumai 9, then carry out rational close planting according to the characteristics of the variety and local conditions, and apply compost fermented with enzyme bacteria or decomposed organic fertilizer. In addition, timely drainage after rain in southern regions and timely watering during drought in northern regions are also effective measures for controlling wheat powdery mildew.

The causes of wheat powdery mildew include:

1. Pathogen

In winter wheat regions, the fungal source of spring infection mainly comes from local sources. In spring wheat regions, besides local sources, it also comes from nearby areas where the disease occurs early.

2. Climate

The optimum temperature for the occurrence of this disease is 15-20°C, and the disease develops slowly below 10°C. A relative humidity greater than 70% may cause an epidemic of the disease. In areas with little rain, the disease is severe in years with more rain; in rainy areas, if the number of rainy days and the amount of rainfall are too great, the disease is instead reduced, because continuous rain washes away the conidia on the surface.

3. Management

Excessive nitrogen application causes the plants to remain green and late-maturing, and the disease becomes severe. Improper management, insufficient water and fertilizer, dry land, weak plant growth and low disease resistance also make this disease more likely to occur. In addition, high density leads to severe disease.

The symptoms of damage to wheat are as follows:

1. Parts affected

This disease can infect all organs above ground on the wheat plant, but it mainly affects the leaves and leaf sheaths, and in severe cases the glumes and awns can also be affected.

2. Stage characteristics

At the initial stage of the disease, white spots of 1-1.5mm appear on the leaf surface, which then gradually expand into nearly round to oval white mold spots. The surface of the mold spots has a layer of white powder, which immediately disperses when subjected to external force or vibration. These powdery substances are the mycelium and conidia of the fungus. In the later stage, the mold layer on the diseased part turns grayish white to light brown, and small black granular dots the size of pinheads are scattered on the lesions, namely the cleistothecia of the pathogen.

Overall, the control of wheat powdery mildew is a combination of selecting disease-resistant varieties, using chemical agents and physical control methods.