How should flower greenhouses be managed when there is heavy rain?

In summer, rainfall increases. Because agricultural facilities age and leak rain on the market, or because the terrain is relatively low-lying, many greenhouses have water accumulating in them and humidity is too high. The emergence of pathogens first has relatively high humidity requirements; with heavy damp rain, humidity inside the greenhouse may reach 100%, which is very favorable for the germination of pathogen spores. Second, rising temperatures are also very favorable for the growth of pathogen hyphae, which can rapidly invade the host and cause disease outbreaks. Continuous high-temperature, rainy weather can produce multiple infection cycles in succession, which is very favorable for large-scale outbreaks of disease.

High temperatures reduce the dispersibility of biological colloids, turn ester compounds into layers, lower enzyme activity, and in severe cases even damage cell structure. High temperatures also affect plant respiration intensity, causing carbohydrate synthesis in the plant body to be hindered, with catabolism greater than assimilation; especially under conditions of insufficient light and excessively high temperatures, plant reverse growth is severe. When carrying out production management, producers should follow the plant protection principle of prevention and take preventive measures before trouble occurs.

To prevent large-scale outbreaks of greenhouse horticultural plant diseases, producers need to do the following two things well: first, environmental treatment; second, applying pesticides without missing the right timing.

Some practitioners think that if the disease is not obvious, then as long as ventilation is done well it will not harm the crops. Actually this is not the case. The overall growing environment continuously deteriorating and the plants becoming weak, the two combined, is precisely the period when flower diseases occur severely.

For example, if the environment for flower growth is not thoroughly treated, the pathogens that breed will spread through the following routes: first, in the latter half of the night when the temperature drops slightly, water droplets on plant leaves will carry pathogens and invade through the stomata; second, through mechanical damage to the plants, pathogens will invade from the wounds, and when encountering high temperatures of 28°C to 35°C, with poor ventilation, pathogens will multiply profusely in the greenhouse, and disease will occur very quickly; third, as substrate humidity continuously rises, root activity declines, and soil-borne diseases will increase.

Therefore, the following should be noted in management:

1. After draining water from the ground, carry out treatment by spraying lime powder, carbendazim, etc. under the seedbeds and on the walkways on the ground;

2. Ventilation strength needs to be increased, especially nighttime ventilation and internal circulation strength should be increased;

3. Increase the proportion of potassium fertilizer and calcium fertilizer used, cultivate robust plants, and improve the plants' own resistance to disease;

4. Spray systemic and preventive pesticides without missing the right timing, eliminating pests and diseases before they cause harm;

5. When diseased plants are found, they should be promptly removed from the greenhouse and deeply buried or burned.