Vegetables grown in thin-film greenhouses are often misdiagnosed as diseases due to improper fertilization methods and neglect of ventilation, which causes excessive greenhouse toxic gases and harms vegetables, and they are often misdiagnosed as diseases, leading to insufficient or even no harvest.
1. Harm:
1. Nitrogen
Due to excessive application of quick-acting chemical fertilizers such as urea and ermium sulfate, or improper fertilization methods, such as the application of unripe organic fertilizers, the decomposition of ammonia under high temperature conditions in the shed will damage the vegetables and cause the leaf edge tissue to appear watery. Spots, when severe, the whole leaves wilt and die. It is often misdiagnosed as frost-old disease or other diseases. Vegetables that are sensitive to ammonia include cucumber, tomato, and zucchini.
2. Nitrous acid gas

Applying too much ammonium nitrogen fertilizer at one time will reduce the effect of certain bacteria and cause local acidity in the soil. When the PH value is less than 5, nitrous acid gas is produced, which can cause white spots on the vegetable leaves, and serious whole leaves become white and dead. It is often misdiagnosed as powdery mildew. Vegetables that are sensitive to nitrous gas include eggplant, cucumber, zucchini, and celery. , Pepper, etc.

3. Ethylene and chlorine
If the quality of the agricultural film or mulch film is poor, or there is mulch film residue in the ground, it is exposed to the sun, and under the high temperature conditions inside the greenhouse, it is easy to volatilize and produce harmful gases such as ethylene and chlorine. When the concentration reaches a certain level, the vegetable leaf margins or veins will turn yellow, and then turn white. In severe cases, the whole plant will die. It is often misdiagnosed as bacterial keratoderma, which is particularly harmful to cucumbers. In addition, heating in winter is heating up, and if the fuel is not burned sufficiently, toxic gases will be generated, and if the ventilation is not timely, too much carbon dioxide will accumulate. Affect vegetable production.
Two, prevention:
1. Fertilize reasonably.
The organic fertilizer used in the greenhouse must be fermented and decomposed, the chemical fertilizer must be high-quality, and urea should be mixed with calcium superphosphate. The base fertilizer should be applied 20 cm deep, and the topdressing chemical fertilizer should be about 12 cm deep, and water in time after application.
2. Ventilation.
In sunny and warm weather, ventilation and ventilation should be combined with temperature adjustment, and ventilation and ventilation should be properly conducted in rainy and snowy weather.
3. Use safe and non-toxic agricultural film and mulch to remove waste plastics and their residues in the greenhouse in time.