Strange phenomenon of cotton: young peaches in the middle and upper parts crack ahead of time

Recently, some farmers called to reflect the strange phenomenon in cotton production: the big bolls in the lower part and the early-growing bolls grew normally but did not open bolls, while the tender bolls in the middle and upper parts cracked ahead of time, and some of them cracked and rotted bolls appeared. The Agricultural Bureau of Wuqiao County immediately organized technicians to go deep into the field to find out the reason.

I. Field performance

Early sowing, upper 1~3 fruit branches due to rain or pest damage without bolls or only a few bolls early cotton field, the number of cracks in the middle and upper cotton is relatively large, that is, from the lower 7~8 fruit branches of the outer bolls and 9~10 fruit branches of the inner bolls, the diameter is about 2.5~3.1 cm, the boll shell surface shrinks thin cracking, browning from the top of the boll shell to more than two-thirds of the position, bracts yellow. The average number of dehisced bolls per plant in this kind of cotton field was 2~3, 4~5 in many cases, and 0.5~0.8 in general cotton field, and the number of dehisced bolls in late cotton field was the least.

II. Cause analysis

1. It is related to the sowing date. The early sowing cotton field, because of early development and the influence of continuous high temperature and sufficient light from late June to early July, has 2~3 or even more pre-harvest peaches, which makes the reproductive growth vigorous, but the vegetative growth relatively weak. From late July to early August, the average temperature is 1.3℃~1.5℃ lower than that of the same period of previous years, and there are more continuous rainy days (cotton is a thermophilic and phototropic crop, requiring higher accumulated temperature and stronger light), and the light is insufficient and the photosynthetic products are reduced in continuous rainy days. The fiber and seed growth in the middle and upper tender bolls were normal, but the growth rate of boll shells was seriously delayed due to the lack of nutrition supply, especially the synthesis of soluble carbohydrates and other hydrophilic substances in the boll shells, which caused the boll shells to dehydrate and crack ahead of time.

2. Variety factor. There were some differences in dehiscence degree among varieties in cotton field. The varieties with thin boll shell and heavy boll weight, such as 7886, were more open than those with thick boll shell and low boll weight.

3. Different spraying times and application methods also caused differences in cracking degree. The plots with more spraying times were obviously heavier than those with less spraying times. The analysis is closely related to spraying methods. Farmers are accustomed to spraying several kinds of pesticides together, even spraying some fertilizers and foliar fertilizers together. The dispensing method or procedure is not correct, so that the middle and upper cotton bolls are coated with more pesticides and fertilizers. The pesticides and fertilizers accumulate on the boll shell surface. The middle and upper tender peaches are in rapid growth period. The accumulation of pesticides and fertilizers affects photosynthesis on the one hand, and accelerates the dehydration and aging of the boll shell surface on the other hand, and promotes its early cracking.

4. Climatic factors. Climatic factors were the most important factors causing boll dehiscence. From late July to early August, there were more than ten consecutive rainy days, the temperature was 1.3℃~1.5℃ lower than that of the same period in previous years, the light was seriously insufficient, the photosynthesis and photosynthetic products decreased, resulting in unbalanced development of cotton bolls inside and outside, normal accumulation of internal substances, inhibition of dry matter accumulation of boll shells, slow growth or stop growth of boll shells, resulting in imbalance of proportion and cracking of bolls.

5. And aphid control effect is good or bad. Due to the serious occurrence of aphids this year, cotton bolls dehisced more than cotton fields with good aphids control effect because of various reasons and weak plant nutrition growth.

III. Preventive and remedial measures

1. Sowing late at the right time. According to the local climate characteristics and planting experience in previous years, late sowing at appropriate time ensures complete seedling, reduces the occurrence degree of seedling disease, promotes healthy growth of seedlings, improves plant disease resistance and stress resistance, reduces the number of peach, ensures the proportion of three peaches, and realizes balanced yield increase.

2. Choose varieties with strong resistance, and do a good job in planting varieties. For old cotton fields and seriously ill plots planted for many years, varieties with strong growth and fast growth and development process in early planting stage shall be selected to prevent the occurrence of early reproductive growth caused by thin seedling stage. Farmers with large cotton planting area can choose 2~3 varieties to plant together to prevent losses caused by various extreme abnormal weather effects.

3. Timely control of pests and diseases and scientific compound chemicals. Important pests and diseases in cotton fields include red spiders, aphids, stink bugs and cotton bollworms, which should be closely monitored everywhere. When the occurrence situation reaches the control index, timely control can not be delayed to prevent the cotton plant from being seriously damaged due to delaying the key period of pest control, resulting in the occurrence of premature senescence of cotton plants. The following points should be paid attention to in the compound medicament: ① The compound medicament with good curative effect can be used alone to prevent and control various pests;② Prepare a dispensing barrel, and the single agent or fertilizer to be compounded shall be internalized in the dispensing barrel for later use according to the use concentration;③ Add half a barrel of water into the sprayer first, then put the diluted liquid medicine or fertilizer into it, and spray it after repeated stirring with water;④ The medicament shall be prepared and used immediately.

4. Remove mulch film in time, do a good job of intertillage, promote root system to tie down, improve plant drought resistance, disease resistance and stress resistance.

5. Enlarging row spacing properly, reserving leaf branches, increasing vegetative body area and improving stress resistance. According to experiments, cotton has more than one crazy branch and more than one root. Only when there are more roots and deep roots can the purpose of deep roots, disease resistance and anti-aging be realized. According to investigation, cotton bolls of 80~ 100cm row spacing have not dehisced in advance so far.

6. Treatment of dehiscent bolls. At present, cracked cotton bolls can not be removed temporarily as long as there is no continuous rainy weather, nutrients on leaves and fruit branches can still be transmitted into cotton bolls through boll stems, which is beneficial to properly increasing boll weight. Cotton bolls which are irrigated with water due to rainfall and infected by germs should be removed in time and taken out of the field for centralized treatment or drying.