The trend of “south drought and north sorghum†has increased. Most of the cotton areas in this year have more rainy weather, and the cotton fields are more sullen. The cotton rotten bells may become an unfavorable factor affecting the high quality and high yield of cotton. Therefore, we should take the opportunity to prevent and prevent it. Cotton enters the bellows and boll opening period. The general year is prone to rotten bells in the middle and late August to the end of September. The incidence of cotton fields is 8%~15%, and the serious plots are over 30%, which is the main threat to high quality and high yield of cotton. .
Cotton is one of the important economic crops of farmers. It is not only an important material for people's livelihood, but also a strategic reserve for the national economy. Therefore, we must pay attention to the important agenda when we do a good job in improving the quality and efficiency of cotton.
The main reason for cotton rotten bells: cotton flowering and bellling period, more rainy weather, heavy rainfall, poor drainage, high humidity in the field, high temperature and high humidity in the ridge, it will cause the breeding and breeding of pathogens, and increase the rotten bells of cotton; nitrogen fertilizer application Excessive, leading to excessive growth of cotton plants, severe depression, disease resistance decreased to cause rotten bells; cotton bell disease, cotton bollworm, corn borer and other pests and diseases seriously caused rotten bells. In recent years, with the popularization of insect-resistant cotton varieties and the promotion of plastic film mulching cultivation techniques, the insect-resistant cotton knots are early and concentrated, the disease resistance is low, and the cotton film is easy to prematurely decay. Therefore, the cotton smog occurs early, and There is aggravation, in case of rainy days, it will happen seriously.
How to prevent rotten bells:
"Two control": that is, control of nitrogen, control and long. Control the amount of nitrogen applied in the middle and late stages of cotton growth. At present, most of the cultivation is insect-resistant cotton. It is generally required to apply a certain amount of base fertilizer and bud fertilizer, and not to apply flower-bell fertilizer, in order to prevent excessive growth and darkening of the shade. It is necessary to control nitrogen, increase phosphorus and supplement potassium, and apply foliar fertilizer. Such as: use 2 ~ 3% of urea filtrate, 2% potassium dihydrogen phosphate solution, spray Shi Bao and other foliar fertilizer spray; timely "chemical control" can prevent cotton field depression, prevent rotten bells. According to local conditions, it is advisable to carry out chemical control as early as possible. Generally, the initial flowering period and the flowering period are the key periods of chemical control. Strong and rainy weather, after the topping of cotton, it is prone to axillary buds, and the fruit branches are prosperous, causing the cotton fields to be depressed and causing rotten bells. 5 to 8 days after the initial flowering period and cotton topping, 45~80 grams of ketamine per hectare, sprayed once at the top of the cover; about 10 days after spraying, there are still prosperous heads, 30 times per hectare with ketamine 30 ~40 grams, can be sprayed again. The spray of liquid is 50~75 kg.
"Two defenses": that is, prevent depression and prevent pests. Pushing the plants and ridges, strengthening the ventilation and light transmission, improving the microclimate in the field, can effectively prevent the cotton field from being closed and control the development of the rotten bell. In the cotton field with high density, when there is more rain in summer and autumn, the plant can be ridged 2~3 times to effectively reduce the humidity in the field, control the length and reduce the bad bell; 75% chlorothalonil or 50% can be used in the middle and lower parts of the cotton plant. The spray of carbendazim WP 500-600 times solution and 70% methyl thiophanate 1000 times solution can effectively prevent the occurrence of rotten bell disease. At the same time, it is also necessary to prevent and control insects such as cotton bollworm, corn borer and red bollworm.
"Two excerpts": the removal of mad cockroaches, old leaves; removal of sick bells, old bells. Due to the rainy weather, cotton vegetative growth is too prosperous, easy to form madness and prosperous, timely removal of mad cockroaches, diseased leaves, old leaves, can effectively prevent the occurrence of bell disease, timely hit the group, go buds, cut empty branches, Removal of empty trees, etc., can improve ventilation and light transmission conditions in cotton fields. It is an effective way to prevent cotton rotten bells by removing the sick bells, old bells, and then drying the bolls in time. Therefore, timely removal of the diseased bell and old bell in the middle and lower part of cotton can effectively prevent rotten bells and reduce losses.
"Two sun": that is, the sun is drying in the field, and the bell is ripening. Before the arrival of the rainy season, it is necessary to cultivate the ridges and gullies in order to smooth the drainage; in case of heavy rain and heavy rain, it is necessary to remove the accumulated water in time; after the overcast rain, it is necessary to push the plants and ridges in a large amount in time, and when the soil is dry and hard to enter the ground, the arable and loose The surface soil allows the surface and the middle and lower parts of the cotton plant to be aired in time to facilitate ventilation and light transmission and reduce the humidity in the field. And timely remove the sick bell, old bell, concentrated on the cement floor or roof, covered with plastic film, to increase temperature and ripening, improve the quality of the spun, improve fiber quality. It is also possible to spray 100~300 times of 40% ethephon on the cotton bolls, and then cover the film to make the bolls better.
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