Causes and Prevention Measures of Gas Poisoning in Greenhouse Vegetables

When growing vegetables in greenhouses or polytunnels during winter and spring, gas poisoning in greenhouse vegetables occurs from time to time because of failure to ventilate in time or improper management of cultivation measures and other reasons. In mild cases it affects plant growth and development, and in severe cases the plants wither and die. So what are the causes of gas poisoning? Let's take a look together.

I. Common types and causes of gas poisoning

1. Ammonia gas and nitrous acid gas

Ammonia gas and nitrous acid gas in the greenhouse mainly come from nitrogen fertilizers and organic fertilizers applied to the soil. When high temperatures are encountered, a large amount of ammonia gas is decomposed in a short period, causing burns to the vegetables.

2. Toxic gas from plastic film

Some inferior plastic films release toxic gases during use, such as chlorine gas and ethylene, which can invade the interior of the planting area and seriously affect the yield of vegetable varieties.

3. Smoke-generating pesticide formulations

When smoke-generating pesticide formulations are used in excess, they can also cause the top leaves and leaf margin tissues of vegetables to wilt and die, and the damage is even more severe under conditions of high temperature and high humidity.

4. Carbon monoxide and carbon dioxide gas

When coal fires are used for heating in the greenhouse, incomplete combustion or poor ventilation often causes carbon monoxide and carbon dioxide to become too concentrated, causing varying degrees of harm to the normal growth of vegetables.

II. Harmful symptoms

Generally, ammonia damage mostly occurs on the outer leaves of the plant. The affected parts appear water-soaked, and the leaf margins appear scorched, then gradually wilt, turn black and die. Nitrous acid generally occurs on the middle leaves of the plant. The affected leaves develop water-soaked spots, and in severe cases the leaves turn white and die. When harmed by carbon dioxide gas, the leaf veins first show obvious dotted or patchy white spots or yellow spots, and in severe cases the entire leaf becomes a green net-like skeleton and gradually dies. Carbon monoxide poisoning causes the leaves to wither, and when the concentration is too high, the vegetables suffocate and die within a short time.

III. Prevention and control methods

First, pay attention to ventilation and air exchange. When the temperature is too high at noon, open the vents to allow air circulation. Even on cloudy or rainy and snowy days, ventilate and exchange air as much as possible at noon to reduce the concentration of harmful gases. Next, fertilize reasonably. Use mainly decomposed farmyard manure, appropriately apply additional phosphorus and potassium fertilizers, apply as little nitrogen fertilizer as possible, and at the same time adhere to the principle of mainly basal fertilizer with supplementary topdressing. Try not to use toxic plastic films that have added plasticizers or stabilizers. When using coal fires for heating, try to make the fuel burn fully, and at the same time install a chimney to discharge the harmful gases.

IV. Remedial measures

For greenhouses where gas poisoning has already occurred, increase ventilation as soon as possible and promptly remove harmful gases. For gas damage caused by topdressing, water promptly to reduce the fertilizer concentration, or spray foliar fertilizer to enhance the plant's resistance and reduce the toxic damage. For damage caused by carbon dioxide, spray lime water or lime sulfur mixture as a remedy.

The above is an introduction to the causes and prevention measures of gas poisoning in greenhouse vegetables. We hope it can help you. If you want to learn more related knowledge, please stay tuned to us.