Generally speaking, it is recommended to choose sunny days, around 10 am. During this period, the temperature in the vegetable greenhouse rose, the plants grew well, and the absorption pharmacology was good, which was suitable for dispensing. At 25℃~30℃, most bacteria and pests are active, and vegetables grow comfortably. At this time, the foliar liquid medicine can be quickly dried after spraying, forming a uniform film with good efficacy and no phytotoxicity. Therefore, the spraying time in the greenhouse in winter should be between 10:00 ~ 14:00 on sunny days. The air humidity in the shed is also an important factor affecting the efficacy. Spraying chemicals when wet will not only increase the air humidity and reduce the efficacy, but also cause drug damage more easily with organic copper preparations. Of course, under strong light and high temperature conditions, it is also easy to cause drug damage.

You can't take medicine immediately after the long cloudy day clears up. It's sunny. Vegetable leaves are thin, yellow and tender, and the fiber structure is weak due to long-term weak photosynthesis. At this point, it is easy to cause drug damage. Before spraying, the vegetable greenhouse should be ventilated and exposed to sunlight for 1-2 days. Use a fine spray or better atomized spray. Don't spray too much on the shoots and shoots of crops, and don't spray directly at close range. The liquid medicine does not drip, does not form a big dew point, and the front cover leaf of the shed is not wet.

Cloudy diseases in vegetable greenhouses are serious in winter. It is suggested to reduce the dilution concentration or total amount of drugs and extend the application interval. Be careful when spraying chemicals containing ingredients that inhibit crop growth. Generally speaking, azoles are widely used to control diseases, but they can inhibit the growth of vegetables. Therefore, we must be careful when using these drugs.

Find out the root cause of abnormal vegetable growth and take corresponding measures. For example, the root cause of botrytis cinerea is poor illumination, high humidity and low temperature. It is necessary to strengthen the illumination in the shed, raise the temperature, ventilate and reduce the humidity. After the pests and diseases of greenhouse crops are discovered in advance, they should be classified and controlled before the occurrence of large incubation period, and attention should be paid to the early prevention and control of protective fungicides regularly; Especially before the arrival of bad weather, spray broad-spectrum fungicides, fumigants or alternately spray internal fungicides to kill most pathogenic bacteria, such as fungi and bacteria. The sterilization effect is comprehensive, which can save manpower, material resources and drug costs. If we wait until the onset, the prevention and control effect will be poor. At the same time, there are many diseases in the middle and late stage, and there is no chemical control, which will cause great losses to crops.