Strengthening the Management Technology of Cotton in the Middle and late stage in Hebei Province

At present, spring sowing cotton in Hebei Province has entered the flowering and boll stage from south to north. Due to good sowing foundation, timely field management, more precipitation in early stage and sufficient light, cotton plant type in Hebei Province is orderly, growth is stable, disease and pest damage is light, and field growth is generally better than previous years. Recently, the provincial cotton expert advisory group conducted a cotton field inspection in 21 counties (cities) of Handan, Xingtai, Hengshui and Cangzhou. According to the investigation, the average plant height is 60~70 cm, the number of leaves on the main stem is 15~17, the number of fruit branches is 8~12, the growth process is basically normal, and the shelf for high yield is erected. At present, the main problems exist: firstly, due to excessive rainfall in the early stage and untimely chemical control, individual plots grow vigorously and plant type is high; secondly, due to recent continuous high temperature, some cotton fields aphid, red spider, mirid bug and other pests occur more frequently, which brings adverse impact on cotton growth. At present, it is the flowering period of cotton, which is also the key period for the management of cotton in the middle and late stages. It is required that all localities should seize the favorable opportunity, adjust measures to local conditions, classify and guide, strengthen the management of cotton in the middle and late stages, and strive to win a bumper harvest of cotton.

Cotton experts in the middle and late management guidance is:

1. Scientific fertilizer and water management

1) Timely watering. After flowering, cotton fields enter the peak period of water demand. According to the weather and actual conditions of cotton fields, water in case of drought, especially in recent continuous drought and high temperature weather, and do not have the fluke mentality of waiting for rain. The watering index is that the top leaves of cotton plants can be watered at 4 o 'clock in the afternoon.

2. Heavy application of flower and boll fertilizer. Cotton flowering and boll period is the key period for fertilizer, irrigation or precipitation should be combined, timely topdressing. General mu topdressing urea 10 kg. The cotton field with premature senescence trend should be applied with appropriate potassium fertilizer. Specific to see cotton growth appearance, according to weather changes, flexible grasp. For cotton fields with dry weather, less base fertilizer, thin soil fertility and weak cotton growth, flower and boll fertilizer should be applied early and heavily to achieve "flower application and boll use". Deep furrow application is advocated to improve fertilizer efficiency.

3. Spraying foliar fertilizer to prevent premature aging. Cotton late growth can be foliar spraying 60 times urea solution or 500 times potassium dihydrogen phosphate solution, spray 70 kg of liquid medicine every mu, spray once every 7 days, continuous spray 2~3 times.

II. Timely chemical control and timely pruning

According to the principle of "a small number of times, first control and then promotion, first light and then heavy", scientific chemical control and timely pruning shall be carried out according to cotton growth and precipitation.

1. Scientific application of metanide. Chemical regulation should be flexibly mastered according to cotton growth and weather conditions. It should not be used when soil is short of water and cotton growth is hindered. Chemical control should be carried out in time before topdressing or watering during flowering and boll period. Generally, 2~ 3g of mepiquat chloride is used per mu after initial flowering, 1~ 2g of mepiquat chloride is used per mu for cotton fields with poor growth, 3~ 4g per mu for cotton fields with strong growth, 50kg of water is added, evenly sprayed, and timely supplementary spraying is required in case of rain after spraying. Fertilizer water is good, grow flourishing cotton field can spray 2~3 times, every time interval is not less than 1 week.

2. Top in time. According to the principle of "time to different branches, branch to different time", the medium fertility cotton field is generally topped on July 15~20, and the late cotton field can be postponed to July 25. Cotton edge beating time is generally before August 10. Leave leaf branch cotton field, leaf branch fruit node reaches 3, want to knock off top in time, or cotton plant sees flower when knock off leaf branch top. Empty plants and branches should be removed in time to improve ventilation and light transmission conditions.

3. Adopt chemical ripening technology. In the later stage, when low temperature, rainy weather and insufficient light occur, the cotton fields with greediness and late maturity can be sprayed with ethephon to promote cotton boll maturity.

III. Integrated pest control

The main diseases and insect pests in cotton field of our province include cotton bollworm, aphid, cotton mirid and verticillium wilt. According to the analysis of current cotton disease and insect occurrence and meteorological conditions, the control of aphid is mainly done in Handan, Xingtai and Hengshui cotton areas, and the control of cotton mirid is emphasized in Cangzhou cotton area. Attention should also be paid to controlling other pests, especially the older larvae of the third generation cotton bollworm.

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

2. Mistae. To control cotton bollworm, systemic insecticides and strong knockout insecticides should be used, such as spraying 50~75 ml of 40% profenofos ec or 70 ml of 25% octylcyanide ec mixed with 60 kg of water per mu. The aphid and cotton bollworm can be treated by 2~3 times of continuous application at intervals of 5~7 days.