WHEAT CROWN ROT

The wheat is now in the milky stage. Mr. Jun, who owned a big wheat farm, is looking at the wheat field, anxious that the nearly 30 hectare of wheat he planted was found to be damaged by wheat crown rot.

"Some of the wheat stalks dried up. it rained two days ago, and wheat ears turned black." He told that in previous years, the field would also have wheat crown rot disease, but much less. However, this year, the crown rot is particularly serious, and wheat grains damaged by crown rot are very small. He estimated that wheat yields would be a reduction of 3-4.5 tons per hectare.

In the end of May, the experts from Plant Protection and Plant Inspection Station explained the disease pathogenesis of wheat crown rot, "wheat crown rot is a new disease triggered by the conditions of conservation tillage, the main reason is the changes in the ecological environment of the farmland. It infests the wheat rhizome, which is the key channel for water and nutrient transportation. Wheat crown rot will cause dead seedlings, black stems, or white spikes, so it is also known as the cancer of wheat."

The crown rot pathogen (Fusarium pseudograminearum or Fusarium culmorum) can survive for up to two years on infected cereal stubble from previous cereal plants, volunteer cereals or grass weeds. For this reason, stubble management is an important aspect in the control of crown rot.

In recent years, the annual occurrence pattern of wheat crown rot in the crop rotation of wheat and corn is: the corn seeds are sown after wheat harvest, but the infected root stubble of wheat stays in the field, and continues to reproduce in the wet soil during the corn season. After the corn harvest, infected wheat stubble crushes together with the corn stalks with shallow rotary tillage, so the crown rot pathogen spreads mainly in the shallow layer of the soil, which cause the potential risk of wheat crown rot in the next year. The accumulation and spread of the pathogen makes the disease worsen year by year.

Fig. The annual occurrence pattern of wheat crown rot in the crop rotation of wheat and corn

Wheat crown rot is hard to control but can be preventable. Deep ploughing and seed treatment are effective ways to prevent wheat crown rot. Besides, enhancing crop resistance by organic fertilizer, choosing tolerance wheat varieties, using non-saline water, and some other methods can effectively reduce the occurrence of wheat crown rot in the field. Results from field practice show that, the prevention effect of deep ploughing more than 25 cm after corn harvest reaches 67.57%, seed treatment reaches 67.11%, using organic fertilizer as base fertilizer reaches 23.68%.

Key method for prevention and control of wheat crown rot:

(1) Deep ploughing: deep ploughing more than 25 cm after corn harvest, then rotary tillage and sowing.

(2) Wheat varieties: choose the wheat varieties with good tolerance to wheat crown rot.

(3) Seed treatment: fludioxonil, difenoconazole, tebuconazole are recommended fungicide.

(4) Bio-fertilizer: Trichoderma, bacillus spp. and other antagonistic microorganism are recommended. They can accelerate straw decomposition, adjust the soil microbial structure, accelerate straw decomposition, and eliminate or inhibit the pathogens.

(5) Fertilizer management: reduce nitrogen fertilizer, and appropriately increase phosphorus and potassium fertilizer. Avoid using saline water for irrigation.

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