Management techniques in the Middle and later stage of Cotton growth

"Greater Heat" has passed, "the Beginning of Autumn" is coming. Cotton in southern Hebei has entered the peak period of blooming flowers and bolls, and the main problems at present are as follows: first, due to the excessive rainfall in the early stage, the lack of chemical control, the growth of some plots is prosperous, and the cotton plant is on the high side; second, due to the recent persistent high temperature, the occurrence of insect pests such as aphids and red spiders in some cotton fields is too heavy, which adversely affects the growth of cotton. At present, it is the cotton blooming period, and it is also the key period for the middle and later stage of cotton management. in view of the climate characteristics of this year, we should seize the favorable opportunity, adjust measures to local conditions, classify and guide, earnestly strengthen the management of the middle and later stage of cotton, and seize a bumper cotton harvest.

1. Fertilizer and water management should apply top fertilizer on the basis of re-application of flower and boll fertilizer in the middle of July.

After flowering, the cotton field enters the peak period of water demand, according to the weather and the actual situation of the cotton field, water should be watered in case of drought. The watering index is 4: 00 p. M. when the top leaves of cotton plants wilt, they can be watered. In general, under the condition that it has not rained continuously for 7 to 10 days during the summer and autumn high temperature, ditch irrigation is carried out immediately before the outcrop of the drought phase to ensure timely water supply. And timely take advantage of the tide to break the plate to prevent cracking, enhance the drought resistance of cotton plants, and reduce the shedding of buds and bolls.

Second, pruning and branching at present, most of the cotton fields have hit the top. The peak time of cotton is usually before August 10. There are 2-3 fruit nodes in the lower fruit branch and 3-4 fruit nodes in the middle fruit branch, and the number of upper fruit nodes depends on the growth of cotton plant. When hitting the tip of the group, pay attention to keep the leaves on the last fruit branch. It is necessary to remove empty plants and branches in time to improve ventilation and light transmission conditions. For superfluous buds, you should hit them as you go.

Third, pest control August and September is a period when many kinds of cotton pests are rampant, and it is also a key period for protecting buds and bolls and seizing cotton. The prevention and control of diseases and insect pests should adhere to the control strategy of "focusing on cotton bollworm and Verticillium wilt, as well as other diseases and insect pests", and achieve the principle of pest, disease-related, mixed and cross-drug use, and control all kinds of diseases and insect pests, especially the damage of cotton bollworm in the primary stage.

1. Cotton bollworm. Chemical control should be carried out when 100 plants of more than 3 instar larvae reach 5, and pyrethroids, organophosphorus pesticides or compound preparations with contact or stomach toxicity should be selected, and the amount of liquid should not be less than 60 kg per mu.

two。 Aphids. Spray control with 15 grams of imidacloprid per mu, or spray with 2000 times of acetamiprid or 1000 times of 0.3% matrine; when it is dry for a long time, we should pay attention to control the occurrence of red spiders, and when medication is needed, we can choose the mixture of 1500 times of 15% imidacloprid and 1.8% avermectin. At the same time, it has a remarkable effect on the control of cotton leaf mites and can achieve the effect of "one spray and multiple treatment".

3. Cotton Verticillium wilt. Should be changed from flood irrigation to trench irrigation, the incidence can be reduced by 50%, timely drainage, to achieve irrigation, drainage matching. The field investigation was carried out in time, and the diseased plants were sprayed with carbendazim or allicin for 4 times, which could control the spread of the disease and reduce the harm. At the same time of spraying, the effect of root irrigation with one of the above drugs within the range of one square meter of the diseased plant can be significantly higher than that of simple spray.

4. Chemical control for cotton with good fertilizer and water conditions and strong growth, 25% Zhuangzhuangsu 8ml / mu should be sprayed once for cotton with good fertilizer and water conditions, or when 2 or 3 fruit nodes grow in the top layer, so as to control the autumn buds, reduce shedding and achieve the top cover of autumn peach. For late-maturing cotton fields, when most cotton bolls reach more than 45 days and can be between "Cold Dew" and "Frosts Descent", choose the weather period with daily maximum temperature above 20 ℃ for 3-5 days, 40% ethephon 100ml / mu and 40kg / mu, spray the whole plant evenly on sunny days.

Fifth, fine harvest and fine picking in order to improve the quality and grade of cotton, we must do a good job of fine harvesting and careful picking. In the process of cotton harvest and sale, first, we should "pay attention to three searches, adhere to four cleanliness, and implement five points." That is, pay attention to the following three aspects: looking for ground flowers, stiff petals, and "eye shit" flowers (refers to the small flower heads left in the bell shell); adhere to the four clean: shell net, culm net, field net, road net; the implementation of five points: grading, sub-sun, sub-storage, sub-rolling, sub-sale, to ensure that the petals return to the warehouse, high yield and bumper harvest. Second, cotton bags should be used when harvesting and selling cotton, chemical fiber bags should be prohibited, and foreign fibers should be strictly prevented from mixing.