Symptoms and prevention methods for wheat scab disease? Wheat scab is also known as wheat ears, rotten wheat head, red wheat head. It mainly causes seedlings, ear rot, stem rot and stalk rot, and can be harmed from seedlings to heading. The most serious of these is the ear rot.

Classification of wheat scab symptoms

1, seedlings

It is caused by seed infection or disease in the soil. First, the buds become brown, and then the root crown rots. The light stalks are yellow and thin, and the heavy ones die. When the dead seedlings have high humidity, they produce pink mildew (the pathogens and spores).

2, ear rot

When the wheat is flowering, the scorpion produces a water-soaked light brown spot on the spikelets and glume, which gradually enlarges to the entire spikelet, and the spikelet is yellow. When the humidity is high, a pink colloidal layer is formed on the lesion. In the later stage, dense blue-black small particles (bacterial sac shells) are produced. Touched by hand, there is a feeling of protrusion, can not be erased, the grain is dry and accompanied by white to pink mildew. After the onset of spikelets, it spreads to the cob, and the diseased part is brown, causing the spikelets above the affected part to form dead white ears.

3, stem base rot

It can occur from the emergence of seedlings to maturity, and the base tissues of wheat plants become brown and rot after being damaged, resulting in the death of the whole plant.

4, stalk rot

It occurs mostly in the first and second sections of the ear, and water-stained chlorotic spots appear on the leaf sheath at first, and then expand into a pale brown to reddish-brown irregular shape or spread into the stem. When the condition is serious, it causes yellowing of the diseased part, sometimes it is impossible to head or extract the dead yellow ear. When the climate is humid, the diseased part shows a pink mold layer.

Induced pathogens The disease is caused by a variety of Fusarium, mainly Fusarium graminearum, Fusarium oxysporum, Fusarium oxysporum, Fusarium oxysporum and Fusarium oxysporum. The dominant species is Fusarium graminearum. Its large conidia has a sickle shape and has 3-7 membranes. The top is obtuse, the base cells are obvious, and the single spores are colorless. They are pink and viscous.

Small spores are rarely produced. The sexual state is Gibberella zeae, belonging to the ascomycete subphylum. The sac shell is scattered or concentrated on the surface of the host tissue, slightly enclosed in the sub-seat, pear-shaped, with an orifice, the top is a ridge-like protrusion, purple red or purple blue to purple black. The ascus is colorless, stick-shaped, and has a size of 100-250×15-150 (μm) and contains 8 ascospores. Ascospores are colorless, spindle-shaped, blunt at both ends, and are mostly three membranes, 16-33 × 3-6 (μm) in size.

Transmission route and disease conditions In the middle and southern rice and wheat cropping areas in China, the pathogens are over-summer in addition to the diseased bodies, and they are still living in winter, such as rice, corn, cotton and other crop residues. The ascus sac formed on these scums in the following year is the main source of infection. The ascospore maturation is positive in the flowering stage of wheat.

By airflow, wind and rain spread, splashing on the flowering wilting anthers germination, first stagnation of life, and then infect the spikelets, a large number of pink mold layer (bacterial conidia) after a few days. The infection rate is highest during flowering to full bloom. The conidia formed by ear rot have little effect on Honda re-infection, but have a greater effect on adjacent late wheat infection. The bacteria can also overwinter the winters in the diseased seeds with mycelium.

In the northern and northeastern wheat areas of China, the pathogens can overwinter in mycelium or ascospores on residues of wheat, diseased seeds and other plants such as alfalfa, corn, and soybean red mites. In the northern winter wheat area, the mycelium was overwintered on the wheat and corn cobs. When the conditions were appropriate in the next year, the ascospores were ejected to produce ascospores. Scab is mainly transmitted through wind and rain, and the effect of rain is greater.

In the spring, the temperature is above 7 °C, the soil water content is greater than 50% to form the ascospores, and the temperature is higher than 12 °C to form ascospores. In the case of rain or humid air, ascospores mature and are scattered on the anthers, and the episodes of the spikelets are infected by filaments. Late maturity, thick hulls, and heavy-tolerant cultivars are heavier; the amount of diseased bacteria in the field is heavy; the terrain is low, the drainage is poor, the soil is sticky, the nitrogen fertilizer is applied, the density is high, and the field is severely affected.

Control method

1. Select resistant (resistant) disease varieties

Although no immune species have been found, there are some resistant varieties with good agronomic traits, such as Sumai No.3, Sumai No.2, Xiangmai No.1, Yangmai No.4, Wanya No.2, Yangmai No.5 and No.158. , Liaochun No. 4, Zamai No. 5, Xingmai 17, Xi Nong 88, Xi Nong 881, Zhou Mai 9 - Dianyou 688, Xin Baofeng (7228) Mianmai 26, Qumai 27, Wan Year 2, Zheng Yin No. 1, 2133, Ning 8026, Ning 8017, etc. Spring wheat has Dingfeng No. 3 and Ningchun No. 24. All localities can be selected according to local conditions.

2. Agricultural control

Reasonable drainage and irrigation, the wetland should be drained. After harvesting, we should deepen the mites and reduce the source of bacteria. Sowing at the right time, avoiding the rain during the flowering period. It is recommended to apply the compost of the enzyme bacteria, adopt the formula fertilization technology, apply the fertilizer at the same time, avoid the partial application of nitrogen fertilizer, and improve the disease resistance of the plant.

3. Lime water soaking before planting. For the method, see wheat smut.

4, chemical control

1 Seed dressing with stimulation bacteria. Spray the seeds with 100-150 g of solid microbial agents or 50 ml of liquid microbial agents every 6792, mix well, and dry them for seeding.

2 The key point of prevention and control is to prevent the occurrence of ear rot during the flowering stage of wheat. Spray 50% carbendazim WP 800 times or 60% carbendazim hydrochloride (anti-mold) WP 1000 times, 505 thiophanate-wet WP 1000 times at the beginning of flowering period, 50 More than 100% of the WP can be 800-1000 times liquid, 605 moldy mildew WP 1000 times liquid, can be controlled once every 5-7 days.

It can also be sprayed with a mobile mister. In addition, in the middle and late stage of wheat growth, scab, wheat bran, and armyworm mixed area, 667m2 with 40% chlorpyrifos 30ml or 10% anti-carbocarb 10g plus 40% chlorhexidine 100g or 60% anti-mildew 70g plus dihydrogen phosphate Potassium 150g or urea, high-yield, etc., excellent in control.

This article URL: 2016/2017 Wheat Scab Prevention: Symptoms of Wheat Scab Disease and Prevention Measures

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