Solar greenhouses cultivate vegetables in the deep winter season, and the technical requirements are relatively high. The control of temperature, light, gas, and fertilizer must be reasonable, and it meets the requirements for the growth and development of vegetables. Otherwise, diseases and insect pests are easy to occur, and physiological diseases are particularly prone to occur. Some physiological diseases are difficult to identify. , ease the slow, if not properly identified to prevent and control, will affect the normal growth of plants, thereby reducing production. Common physiological diseases of vegetables in winter are as follows:
First, the roots of seedlings are prone to occur, and adult plants occur occasionally. The yellow leaves appeared on the onset of disease. The aboveground part was wilting and easy to pull up. The underground part did not grow new roots. The root bark showed brown rust and water stains decayed. The main reason is that the temperature is low, soil moisture is high, and light is insufficient.
Control methods: First, watering at the seedling stage and low temperature at room temperature, especially not pouring water, it is best to use the submerged film under irrigation with small water; watering time in the sunny morning, and ensure that at least two days after pouring sunny day. The second is to take care of the wind and strengthen the hardening of seedlings. As long as the temperature is appropriate, it is necessary to let off the wind on cloudy days and cultivate strong seedlings to promote root growth. The third is to uncover the grass and mortar on time. On cloudy days, it is necessary to uncover the cover according to the temperature conditions so that vegetables can make full use of scattered light.
II. Ammonia hazards When seedlings are injured, the leaves become black and die from flooding. When the plants become victimized, yellowing occurs between the edges of the leaves or veins, which leads to blue and green, veins are still green, or the whole plant suddenly wilts. Disease and health departments often have clear boundaries. The reason for the occurrence is the use or accumulation of insufficiently cooked chicken manure or ammonium bicarbonate in the greenhouse, improper application of urea, etc., and less greenhouse ventilation, resulting in ammonia accumulation.
Control methods: Use appropriate amount of farmyard manure that is fully decomposed; avoid accumulation of unfamed chicken manure in the greenhouse; apply ammonium bicarbonate and urea properly; strengthen ventilation.
Third, the cucumber flower topping the middle and lower leaves have leggy phenomenon, the upper stem thin, the leaves become smaller, tendrils are very weak, leading emergence of oats bent, or tightly gathered small leaves, top dense, with a female flower, severe growth point forming bald Sharp, well-organized varieties occur more severely. The reason is that after planting and easing the seedlings, the roots are not controlled well, the topdressing watering is too early and the seedlings are not enough; after the early flowering period, the temperature is not changed and the root absorption activity is weakened.
Control methods: Early harvesting, and removal of part of the female flowers, watering at higher temperatures, sufficient light, topdressing nitrogen fertilizer.
Fourth, nitrogen dioxide gas damage occurred in the upper leaves of the plant irregular light-colored spots or brown spots on the leaves, 2-3 days after the leaves dry, severe plants withered. The specific reason is that the amount of fertilizer is too large, and the soil becomes acidic from alkaline conditions. The activity of nitrifying bacteria is limited, and nitrogen dioxide cannot be converted to nitric acid nitrogen in time to cause harm.
Control methods: Apply adequate amounts of farmyard manure; apply less fertilizer when applying chemical fertilizers, timely watering after application, and strengthen ventilation.
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