Li Guorui Zhang Gang Cui Yingshu Ren Yongxia (Kuantao County Bureau of Agriculture)

Cotton is a kind of economic crop. With the operation of the market, the economic benefits have been increasing year by year, and the cotton planting area has also been expanding. However, the occurrence of yellow wilt disease in cotton has also spread rapidly, and has become a major obstacle to the continued high-yield and stable production of cotton.

1 symptoms of cotton wilt

Cotton yellowing disease is a vascular disease that breaks brown stripes on cotton stalks.

1.1 Blight symptoms

1.1.1 The symptoms of seedling stage: Cotton yellowing disease can occur at the seedling stage, and the incidence peaks before and after budding. There are five types of seedling symptoms: (1) Yellow mesh type. The cotyledons of the seedlings or the leaves of the true leaves turn green and yellow, the leaves are still green, and the leaves are partially or entirely yellow mesh-like.

(2) Yellow type. The cotyledons or true leaves turn yellow, and sometimes the leaves show local dead spots.

(3) Purple type. Cotyledons or true leaves turn purple or appear purplish red spots, veins are mostly purple, leaves gradually withered and died.

(4) blue and dry type. The cotyledon or true leaf suddenly loses water, the color turns slightly dark green, and the leaves are heavy and blue and dry.

(5) Shrinkage type. True leaves thicken and shrunk, leaves dark green.

1.1.2 Symptoms of adulthood: except yellow, yellow, purple,

There is a dwarf type besides the blue and dry type. Its main features are shortening between nodes, bending is not straight, dwarf diseased plants, thick leaves, dark green leaves and wrinkled uneven, a large number of seriously ill plant leaves and withered.

1.2 Verticillium wilt symptoms

Verticillium wilt usually does not show symptoms at the seedling stage. It only begins to develop after budding of cotton, and it has the highest incidence of flowering and ringing. Generally, the middle and lower leaves of the cotton plant showed the symptoms first and gradually developed upwards. Occurrence of light yellow irregular patches began to appear between veins or leaves. Afterwards, the patches gradually expanded and became brown and dry, while the main veins and main veins remained green, showing palmar mottled or flowering watermelon rind. In the midsummer, when there is a long-term drought and heavy rain or flooding, an acute wilting-type symptom often appears. The main vein appears green to gray-green patches, which seems to be burned by boiling water and a large number of leaves fall off.

2 The onset of cotton wilt disease

Fusarium wilt disease generally begins to appear in the middle and early May, and the bud period of cotton buds in mid-late and late June is the peak period of disease. Afterwards, the development of diseases with temperature rise ceases. After the second half of August, there was a second peak of incidence. Verticillium wilt generally begins to develop in the budding stage, and the flowering boll stage is the epidemic period. Continuous cropping in the cotton fields, low-lying terrain, poor drainage, heavy soil quality, untreated cotton seeds, and severe disease in the old cotton region, the incidence in the new cotton area is light.

3 Cotton Verticillium wilt disease control measures

3.1 Select high-yield and disease-resistant varieties

With the development of new varieties, more and more resistant varieties of disease-resistant varieties, such as Zhongzhimian 2 and so on.

3.2 Agricultural Control Measures

3.2.1 reverse rotation. The general incidence of land dumps is more than 3-4 years, and the severely affected land should collapse more than 7 years.

3.2.2 Balanced fertilization. Phosphorus and potassium fertilizers and microelements were added to cultivate strong seedlings and enhance the disease resistance of cotton plants.

3.2.3 Treatment of diseased plants. In the seedling stage, the diseased roots are shallow and the diseased soil and diseased plants can be taken out of the field and buried deeply. After the cotton plant grows up, pull out the diseased plant and debris, bring it out of the field and burn it, and disinfect the soil.

3.3 Chemical Control Measures

3.3.1 Chemical seed dressing. Each 100kg seed is soaked with 200kg water for 24h with 40% carbendazim suspension lkg, which can effectively control the cotton with Verticillium wilt and seedling disease.

3.3.2 spray agents. Spraying fungicides and foliar fertilizers can control the spread of yellow wilt disease in cotton, and increase cotton disease resistance. Generally, they use Greenhenge No. 1, No. 3, No. 4, No. 8 or high-resistance NEB (En Yi Bi) with American Science and Technology.

3.3.3 Apply fulvic acid fertilizers. This kind of fertilizer has a strong inhibitory effect on cotton withering and wilt.

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