Measures to deal with greenhouse vegetables in haze days

Recently, the continuous haze weather in North China has led to weak light and low temperature in the vegetable greenhouse, which has become a key factor affecting the growth of vegetables. Many vegetables have some problems, such as yellow leaves, dry tips, rot at the growing point, retting roots, falling flowers and fruits, serious diseases and so on. In this regard, protected vegetables should take the following measures to manage.

1. Keep the seedlings of the existing vegetables in the greenhouse. In the greenhouse, as long as the temperature reaches more than 18 ℃ during the day and ventilation is carried out for a short time (about 20 minutes), the pesticide can be sprayed when there is no dew on the leaves, and organosilicon auxiliaries should be added to improve the absorption and utilization of pesticides. Taking cucumbers and tomatoes as an example, 60% Baitai + 5% Zhongshengnisin + 72% agricultural streptomycin can be sprayed to control downy mildew, blight and gray mildew, and 5% chlorothalonil or 10% Chlorothalonil smoke agent can be used every 2 to 3 days to carry out airtight fumigation at night to reduce the occurrence and development of diseases. Do not water the vegetables that need to be watered in cloudy days, but spray foliar fertilizer to replenish nutrients and wait for sunny days before watering. The cucumber forming "flower topping" can be thinned properly, and the yellowed leaves can be removed and taken outdoors, sprayed or fumigated in time, so as to reduce the occurrence of wound disease caused by artificial removal of leaves.

two。 Management of continuous cloudy and sunny days. Retting root phenomenon is easy to occur when the cloudy day is more than 5-7 days. In some areas, the haze day is more than half a month, most of the vegetable roots show varying degrees of rust, and there are almost no white roots that can absorb nutrients. If the semi-cloudy and semi-sunny weather causes the temperature to rise gradually, the damage to the seedlings will be less, and if it is suddenly sunny, corresponding measures must be taken. The main results are as follows: (1) when the temperature in the greenhouse rises to 23 ℃, the leaf wilting can be diluted 150x by spraying white sugar + vinegar (50g each), or foliar fertilizer plus white sugar is sprayed on the leaf to increase the air humidity and slow down the wilting phenomenon. When the temperature rises above 26 ℃, wilting can be returned to cover the 2 canopy surface, and roll it up in time when the seedlings return to normal. The performance of the seedlings should be observed the next day. If there is wilting phenomenon, chlorothalonil + streptomycin + brassinolide can be sprayed to reduce the occurrence of diseases and promote the rooting of seedlings. (2) when the seedlings need to be watered, do not water suddenly on a sunny day, when the ground temperature of 10 cm rises to more than 16 ℃, then pour a little water, and increase the ground temperature as much as possible. (3) raise the ground temperature. As long as the seedlings did not wilt after sunny days, there was a light breeze at 23 ℃ in the morning, and the tuyere was closed when the temperature dropped by 1.5 ℃ ~ 2 ℃, and ventilated again when the temperature was above 28 ℃. If the temperature drops only 1 ℃ ~ 1.5 ℃ after 23 ℃ ventilation on a sunny morning, the tuyere does not need to be closed if it rises soon, but the air volume should be increased when the temperature reaches 30 ℃ at noon. In the afternoon, when the temperature dropped to 25 ℃, the tuyere was closed, and if the temperature increased by 1 ℃ ~ 2 ℃, it was beneficial to increase the ground temperature, store heat and benefit the growth of roots.

Wang Shujun of Chengde County Agriculture and Animal Husbandry Bureau