What are the common types of gas damage in greenhouses? Detailed explanation of prevention and control methods
In winter and spring, because the temperature is relatively low, the ventilation in the greenhouse is poor, and timely ventilation is not possible, causing harmful gases in the greenhouse to continuously accumulate, leading to gas damage to the crops in the greenhouse. In mild cases, the leaves turn yellow and the tips dry out; in severe cases, the entire plant dies. So what are the common types of gas damage? How should they be prevented and controlled? Let's learn about them together.
1. Ammonia and nitrous acid
These two types of gas damage are mostly caused by improper fertilization. For example, when applying ammonium bicarbonate as a topdressing or applying large amounts of urea and undecomposed organic fertilizer, combined with high temperature, drought, and poor ventilation, a large amount of ammonia and nitrous acid gas is often produced in a short time, causing plant poisoning. It often appears as water-soaked spots on the leaf margins, as if scalded by boiling water, or gradually turns brown, dries up, and falls off.
Prevention and control methods: Avoid using ammonium bicarbonate, urea, and ammonium sulfate for topdressing in greenhouses. Farmyard manure and organic fertilizer must be fully decomposed before application.
2. Carbon monoxide and chlorine dioxide
When coal or charcoal fire is used for heating in greenhouses, because of incomplete combustion or blocked flues, large amounts of carbon monoxide and sulfur monoxide are produced. When crops are harmed by these two gases, white or yellow spots first appear along the leaf veins, and in severe cases the entire leaf becomes a green net-like skeleton, then slowly dies.
Prevention and control methods: For greenhouse heating, use electric heaters as much as possible and minimize the use of traditional heating methods. Even if they must be used, be sure to use low-sulfur combustion materials, and also ensure safety.
3. Toxic gas released from film
Some plastic films have plasticizers and stabilizers added during the production process, and during use they release toxic gases such as ethylene and chlorine, as well as harmful substances such as diisobutyl phthalate. When this gas damage occurs, light brown irregular spots appear on the leaves, and in severe cases the leaves turn white or even fall off. It can also cause the leaf tips and leaf margins of flowers to turn yellow, or even turn white and dry up.
Prevention and control methods: Ventilate and exchange air in time. Open the ventilation openings at noon on sunny days. Even on cloudy, rainy, or snowy days, carry out short periods of ventilation and air exchange to minimize the harm from toxic gases.
4. Excessive use of chemicals
When chemicals or fumigants are used excessively, or when fumigants are used improperly, such as formalin and methyl bromide, which can only be used in empty greenhouses, using them during the plant growing season can easily cause phytotoxicity. These can all cause plants to show symptoms such as leaf yellowing and dried tips.
Prevention and control methods: The use of chemicals must be scientific and reasonable, and they must not be used carelessly. This is the main measure to avoid phytotoxicity causing gas damage.
The above is an introduction to the common types of gas damage in greenhouses and their prevention and control methods. We hope it can help you. If you want to learn more related knowledge, please follow us.