Control measures of wheat scab

Wheat scab is also known as wheat ear blight, rotten wheat head, red wheat head. It mainly causes seedling blight, ear rot, stem base rot and culm rot, which can be damaged from seedling to heading. Among them, the most serious effect is ear rot.

Symptom classification

1. Seedling rot

It is caused by seed-borne bacteria or infection of diseased remains in the soil. First the buds turn brown, then the root cap decays, the light diseased seedlings are yellow and thin, the severe ones die, and the withered seedlings produce pink mildew (conidia and conidia) when the humidity is high.

2. Ear rot

When wheat blossoms, the slit produces a water-immersed light brown spot on the spikelet and glume, which gradually expands to the whole spikelet, and the spikelet is withered and yellow. When the humidity is high, a pink gelatinous mildew layer is produced in the disease spot. In the later stage, dense small blue-black particles (ascomycetes) were produced. Touch with the hand, there is a sense of protuberance, can not be erased, the grain is withered and accompanied by white to pink mold. After the onset of the disease, the spikelet extends to the ear axis, and the diseased part is withered and brown, so that the spikelet above the affected part forms a withered and white spike.

3. Stem base rot

It can occur from the seedling unearthed to maturity, and the basal tissue of the wheat plant becomes brown and rotten after being damaged, resulting in the death of the whole plant.

4. Culm rot

Most of them occurred in the first and second nodes under the panicle, and water-stained chlorotic spots appeared on the leaf sheath at the beginning, and then expanded into light brown to reddish brown irregular spots or extended to the stem. When the disease is serious, it causes withering and yellowing above the disease department, and sometimes it is unable to heading or pulling out withered yellow ears. Pink mildew layer can be seen in the disease department when the climate is humid.

Induced pathogen

The disease is caused by a variety of Fusarium oxysporum, including Fusarium oxysporum, Fusarium oxysporum and Fusarium oxysporum. The dominant species is Fusarium graminearum, its large conidia is sickle-shaped, there are 7 septum, the top is obtusely round, the basal podocyte is obvious, the single spore is colorless, and it is pink and sticky when gathered together. Small spores are rarely produced. The character is maize scab, which belongs to ascomycete subphylum fungi. The ascus shell scattered or gathered on the surface of the host tissue, slightly wrapped in the seed seat, pear-shaped, perforated, verrucous at the top, purplish red or purplish blue to purplish black. The ascomycetes are colorless, clavate, with a size of 100ml 250 × 15m 150 (μ m) and contain 8 ascospores. Ascospores are colorless, spindle-shaped, obtusely round at both ends, mostly with three septate membranes, the size of which is 16mur33 × 3Mel 6 (μ m).

Route of transmission and conditions of onset

In the double cropping areas of rice and wheat in the middle and south of China, the pathogen overwinters not only in the diseased remains, but also in the diseased residues of rice, corn, cotton and other crops. The ascomycetes formed on these remnants in the following year were the main source of infection. The ascospore maturation is in the flowering stage of wheat. Spread by airflow, wind and rain, splashing down on the wilted anthers germinated, first engaged in saprophytic life, and then infected spikelets, a few days later produced a large number of pink mold layer (pathogen conidia). The infection rate was the highest from flowering to full flowering. The conidia formed by ear rot had little effect on Honda re-infection, but had a greater infection effect on adjacent late wheat. The strain can also oversummer and winter with mycelium in diseased seeds.

In the wheat regions of north and northeast China, the pathogen can survive the winter as mycelia or ascomycetes on wheat plant residues, diseased seeds and other plants such as paspalum grass, corn, soybean red Polygonum and so on. In the northern winter wheat region, the mycelium overwintered over the summer on the spike axis of wheat and corn, and the ascospores were produced in the next year when the conditions were suitable for infection. Scab is mainly transmitted by wind and rain, and Rain Water plays an important role. When the spring temperature is above 7 ℃, the ascomycete is formed when the soil water content is more than 50%, and the ascospore is formed when the temperature is higher than 12 ℃. Under the condition of rainfall or moist air, the ascospores mature and scatter on the anther, and the spikelet is infected by filaments. The late-maturing, thick glume and non-fertilizer-tolerant varieties had more serious disease, large amount of disease and residual bacteria in the field, low-lying terrain, poor drainage, heavy clay soil, partial application of nitrogen fertilizer and high density, and the disease was serious in the field.

Prevention and cure method

1. Select resistant (tolerant) varieties

At present, no immune varieties have been found, but there are some disease-tolerant varieties with good agronomic characters, such as Sumai 3, Sumai 2, Xiangmai 1, Yangmai 4, Wanya 2, Yangmai 5,158,Liaochun 4, Zaomai 5, Xingmai 17, Xinong 88, Xinbaofeng (7228) Mianmai 26, Wanmai 27, Wannian 2, Zhengyin 1, 2133, Ning 8026, Ning 8017 and so on. Spring wheat has Dingfeng 3 and Ningchun 24. All localities can be selected according to local conditions.

2. Agricultural prevention and control

Reasonable drainage and irrigation, wetlands should be ditched and drained. After harvest, the stubble should be ploughed deeply and the source of bacteria should be reduced. Sow seeds at the right time to avoid rain during flowering. Compost made by enzyme bacteria retting is advocated, formula fertilization technology is adopted, timely fertilization, partial application of nitrogen fertilizer is avoided, and plant disease resistance is improved.

3. Soak the seeds in lime water before sowing. See wheat smut.

4. Chemical control

① seeds were mixed with yield-increasing bacteria. Every 6672, the seeds were sprayed with water with solid bacterial agent 100ml 150g or liquid bacterial agent 50ml, and then dried.