Prevention and control of "double rot disease" of cotton

Rotten bolls and rotten peaches are common diseases of cotton, which seriously affect the yield and quality of cotton.

(1) the cause of occurrence

The main results are as follows: 1. Excessive or late application of nitrogen fertilizer results in overgrowth of cotton, closure of field canopy, and weakening of disease resistance of cotton plants.

2. Cotton suffered heavy rain or too much autumn rain in the flower and boll period, excessive humidity in the field and poor drainage, resulting in the breeding and invasion of pathogens.

3. Cotton suffers from red rot, anthracnose and boll blight.

(2) Prevention and control measures

1. Control the humidity in the field. Drainage and waterlogging prevention is the key measure to control cotton rotten bolls and peaches. Therefore, the cotton field should be matched with "three ditches". It is generally required to dig a vertical ditch with a depth of about 35 centimeters at an interval of 5 meters. The drainage ditches around should be unimpeded, and the ditches, edge ditches and perimeter ditches should be connected with each other so that the rain stops and the water is dry.

2. Strictly control the amount of nitrogen fertilizer applied. It is suitable to apply about 10 kg nitrogen fertilizer per mu for flower and boll fertilizer and peach protection fertilizer. Less can not increase flowers, bolls, peaches, more will cause cotton plant crazy growth, greedy green, late ripening, rotten bolls rotten peaches and so on. For cotton fields which have been re-applied flower and boll fertilizer or have no tendency of premature senescence, it is necessary to apply little or no peach fertilizer, or to control its overgrowth and reduce the drop of flowers and fruits.

3. Pruning to improve light conditions. For the growing cotton fields, the middle and lower old leaves should be removed in batches combined with pruning, and for the cotton fields with crazy growth in autumn, remedial measures such as "opening the skylight" (that is, 2 or 3 main stems and leaves in the middle and upper parts should be torn off) and pushing plants to dry to improve ventilation and light transmission conditions.

4. Strengthen the prevention and control of diseases and insect pests. On the basis of previous control, pests such as Helicoverpa armigera and red bollworm should be applied once in the first, middle and last ten days of September. Methods: (1) 1000 times of 90% crystal trichlorfon or 1000 times of 40% omethoate emulsion were sprayed with 60-70 kg per mu. (2) better control effect can also be obtained by manual killing combined with whole branch and shoot. (3) pests in cotton boll stage can be controlled with 25% carbendazim 600x liquid, 25% phoxim emulsion 600x liquid, or 50% topiramate 1000 times liquid, 6065 kg per mu, sprayed every 15 days or so for control.

5. Grab the rotten bell and dry it in time. Cotton plants that have occurred or are about to rot bolls should be picked in time, and the cotton bolls with bacteria should be taken out of the field to reduce the source of the disease and reduce the incidence. The cotton bolls picked should be peeled, dried and harvested in time in order to reduce economic losses.