In recent years, the rot of leaf rot of wheat Helminthosporium has gradually increased to the main disease of wheat, which has a certain impact on agricultural production. Therefore, farmers should take appropriate measures to prevent and control. Today, we will introduce the prevention and control methods of wheat leaf spot root rot.
Symptoms of wheat leaf rot of leaf rot
Wheat Helminthosporium leaf rot, also known as Helminthosporium leaf spot, Helminthosporum rot. It is a typical stage disease in the whole wheat breeding period, which occurs from seedling to heading. In the seedling stage, it causes bud rot and seedling dryness, and the adult stage leads to early leaf rot and ear rot, root rot, stem base rot, leaf spot, black granule, and grain thinness. Among them, the leaf spot of adult stage is the most common and the most serious. Seeds with bud rot, seedlings, and serious diseases cannot germinate, or they may become brown rot and cannot be unearthed when they are germinated. Light onset can sprout soil, but the coleoptile or other underground parts of the disease, mostly died before winter or produce weak seedlings.
Root rot, stem base rot, brown lesions on the coleoptile, underground stem or radicle of the seedling stage, local tissue rot or necrosis, often causing brown lesions at the sub-branch of the underground stem base, brown stalks on the leaf sheath near the ground Shaped marks, size 3 ~ 5 × 1 ~ 3 (mm). The seedlings are often yellowed, and the patches appear light green to pale yellow in the field. The sick seedlings are short, sparse, and the leaves are erect. The tip of the 1~2 leaf in the lower part of the adult stage is 1~2cm, the roots are poorly developed, the secondary roots are few, the surface of the seed root and stem base has brown spots, which can reach the inside, the diseased part is rotted, and the secondary root tip is severe. Or the central part also browns and rots, and the tillers die or the middle and late stages of growth, some or all of the plants are completely dead.
When infected in autumn seedlings or early spring, many oval, light brown spots appear on the near ground blades, ranging in size from 1 to a few mm. After the jointing to the adult stage, the typical light brown, oval to fusiform lesions, size 3 ~ 5 × 1 ~ 3 (mm), surrounded by a yellow halo, the center of the lesion is dry yellow . Ear rot, black granules, and disease at the ear stage often produce brown lesions on the hull or cob. When the lesions are often caused, most of the hulls or cobs become brown, causing severe damage to the half-ears or whole ears. After the seeds were infiltrated with mycelium, the embryos turned brown, and black granules and kernels were thin, which affected the grain grade and seed quality.
The pathogenesis of wheat leaf rot of leaf rot
The pathogens are immersed in the soil or in the summer with the diseased bodies in the soil or on the seeds. The conidia are infiltrated by the coleoptile or the young roots, causing the pathogenesis of the underground stem or the secondary root or the new leaf sheath of the stem. Carrier seeds are an important initial source of leaf spot disease. After the wheat is transplanted to the earing stage, the root rot continues to expand, and the leaf spot disease continues to expand from the bottom to the top. The diseased parts and plant diseases on the ground continue to produce a large number of pathogens, which are spread by wind and rain. Dip dyeing. The incubation period of the disease is 3 to 7 days, and the accumulation of bacteria is fast, reaching the critical population of the epidemic.
When the temperature is 18 to 25 ° C and the relative humidity is 100%, the functional leaves and wheat ears are heavily infected or epidemic. In addition, cultivation measures have a direct impact on the occurrence of the disease. In the production of winter wheat, the seedling stage is easy to occur, and the planting is too dense and too deep. In the field management, all measures to reduce the chance of sick bodies falling into the field or to promote the decay of diseased bodies in the soil as soon as possible (such as deep tillage, fertilization, watering, etc.) are beneficial to the reduction of pathogenic bacteria in the soil. These measures are for wheat growth and development. It is beneficial, and it can enhance the disease resistance, thus reducing the chance of onset.
Prevention and cure method of wheat leaf rot of leaf rot
The disease is a disease in the whole growth period, and leaf spot and ear rot at the ear stage are the key to prevention. Reducing the source of bacteria in the field, reducing the accumulation rate of pathogens, and protecting the functional leaves of adult plants can effectively prevent and cure this disease.
(1) Agricultural control advocates the rotation of crops to reduce the amount of bacteria in the soil, and eliminates the mites in the autumn, accelerates the decomposition of diseased residues in the soil; selects disease-free seeds, sows at the right time, improves the quality of sowing, and reduces the incidence of seedlings.
(2) Advocate the application of compost made by enzyme bacteria.
(3) Select disease-resistant and disease-resistant varieties. Winter wheat has anti-black embryo resistance such as Yumai 47, Zheng Zao 1 and Zheng Mai 9023.
(4) Chemical control:
1 seed treatment. Seed dressing with 50% thiram wettable powder with a seed weight of 0.2% to 0.3%, or 2g of 2% wettable powder per Kg of seed. The 33% carbendazim triazolone wettable powder is seeded at a seed weight of 0.1% to 0.3%. Advocating the use of triadimefon and the production of mixed bacteria can eliminate the effect of triadimefon on the emergence of wheat.
2 Soak the seeds with 70% Daisen Meng zinc wettable powder 100 times for 24 to 36 hours, and prevent the effect by 80% or more.
3 In the adult stage, when the middle and lower leaves of the early stage of the wheat are seriously affected, and when it is rainy, spray 70% mancozeb or 50% thiram WP 500 times or 15% triazol (hydroxy rust). Wet powder 200 times solution, 25% propiconazole emulsifiable oil 2000 ~ 4000 times liquid, 12.5% ​​diniconazole wettable powder per 667m240g water spray, can effectively control the expansion of the disease throughout the growth period.
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