How to prevent the five hazards in winter greenhouse flowers? These key points must be mastered

In recent years, lower-cost plastic greenhouses have been widely adopted by flower growers. However, because winter temperatures inside the greenhouse and soil temperatures are both low, the greenhouse is sealed for long periods, and management is poor, varying degrees of the five hazards - freezing, dampness, wind, gas, and disease - easily occur. In mild cases they affect flower growth; in severe cases they cause flower death, and they should be carefully avoided.

1. Freezing injury. In areas north of the Yangtze River, winter temperatures are relatively low, especially from January to late February, when temperatures inside plastic greenhouses can drop below 0°C for a short time before sunrise, often causing freezing injury. Therefore, for cold-sensitive flowers such as Aglaia odorata, primrose (Primula), and cineraria (Pericallis), a small inner tunnel should be set up inside the greenhouse at night and covered with straw curtains. For flowers grown in the ground, plastic film mulching can also be used to raise soil temperature. After mulching, soil temperature can be raised by more than 1°C. In addition, an appropriate amount of organic fertilizer and phosphorus-potassium fertilizer can be applied, which not only improves soil aggregate structure, raises soil temperature, and provides nutrients for flowers, but also enhances the cold resistance of flowers.

2. Dampness injury. During periods with more rain and snow in winter, if the greenhouse is sealed for a long time, dampness injury is very likely to occur inside. High soil water content not only lowers soil temperature but also causes oxygen deficiency in the soil, seriously affecting the growth and development of flower roots. Therefore, drainage ditches should be opened well around the greenhouse, so that surface water drains quickly and subsurface water seeps away, reducing soil moisture. In addition, according to reports, scattering plant ash on the surface of pots and the ground can not only absorb heat and increase temperature and absorb moisture and reduce humidity, but also increase the potassium fertilizer content in the soil. The greenhouse film should be stretched tight to strictly prevent water accumulation and leakage on the roof during rain and snow.

3. Wind injury. The main reason is that the pressure lines of the plastic film cannot withstand strong winds, causing the plastic film to be blown open or damaged, and the flowers are thus destroyed at once. Therefore, the pressure lines of the greenhouse film must use No. 8 galvanized iron wire, or one nylon rope and one No. 8 galvanized iron wire, and try not to use nylon rope alone. Fix and fasten the iron wire and nylon rope tightly from both sides of the greenhouse.

4. Gas injury. Under sealed conditions, plastic greenhouses easily accumulate harmful gases, mainly ammonia, carbon monoxide, sulfur dioxide, and others. Ammonia gas is mainly produced during the decomposition of undecomposed organic fertilizer, and topdressing chemical fertilizer also produces a large amount of ammonia gas. Carbon monoxide and sulfur dioxide are gases released when coal burns during open-flame heating in the greenhouse. Therefore, when applying organic fertilizer, it must be fully decomposed, and chemical fertilizer should be used as topdressing as little as possible. If it must be used, soil should be covered promptly after application. On clear and windless days, ventilation should be carried out to discharge harmful gases from the greenhouse. Open-flame heating should be avoided in the greenhouse as much as possible.

5. Pests and diseases. Although the humidity inside plastic greenhouses is relatively high, which easily causes the occurrence and development of diseases, because the greenhouse reduces the spread of pathogens by wind and rain, and the temperature and humidity inside can be controlled manually, there is also a favorable side.

1. Anthracnose. Flowers such as camellia, Aglaia odorata, Rohdea japonica, clivia, orchid, and Chinese rose are susceptible. In the early stage of the disease, spray 75% chlorothalonil 500-fold solution, or 70% thiophanate-methyl 1000-fold solution. If the disease is severe, spray once every 7 to 10 days, for two or three consecutive sprays.

2. Powdery mildew. The disease is severe under conditions of high temperature and high humidity, poor ventilation, and poor light in the greenhouse, especially with cineraria suffering the most. Spray 1:1:140 equal-amount Bordeaux mixture, or 25% triadimefon wettable powder 1000-fold solution.

3. Insect pests. Insect pests are mainly aphids, which easily concentrate to damage tender leaf buds, leaves, flower buds, and other parts of flowers. After occurrence, spray 5% fipronil 800-fold solution, or 2.5% deltamethrin 1500-fold solution, or 25% kung fu emulsifiable concentrate 1200-fold solution; the kill rate can all reach more than 95%.