In recent years, the corn field has often twisted and deformed the heart and leaves, and the new leaves are not stretched together. This is the phenomenon of corn leaf curling. There are many reasons for this phenomenon, mainly due to high temperature and drought, improper use of herbicides , damage to thrips, and damage to top rot. So what are the reasons for the corn heart roll? How to prevent it? Xiaobian will explain it to everyone.
1. Insufficient water and water absorption in high temperature and drought
The adaptability of different varieties to climate is different, and the proportion of corn leaf curl is quite different. The drought in the field causes the corn leaf to curl, which generally recovers with the improvement of soil moisture, and recovers quickly after rain or irrigation. Spraying corn leaf fertilizer can promote rapid recovery.
2, caused by physiology
Weeding with nicosulfuron and other drugs during corn growth, if the corn seedling age is less than 3 leaves or more than 5 leaves, or under high temperature conditions, or the application amount is too large, or apply organically within 7 days before or after application of the herbicide Phosphorus pesticides, corn is prone to heart curl, leaf shrinkage, accompanied by irregular yellow drug spots, severe heart leaf rot. When the symptoms are light, most of the plants will naturally recover, and the heart leaves will be severely distorted. Timely fertilization and watering of the affected fields, spraying of brassinolide and high-quality foliar fertilizer are beneficial to promote plant recovery.
3, caused by pests
There are two kinds of pests that cause the corn heart to be rolled: First, the corn is damaged by the thrips in the 3 to 5 leaf stage, and there are chlorotic dots on the leaves, and the thrips are visible in the peeling leaves. You can use nitenpyram, ethyl spinosyn and other drugs to control the thrips, focusing on the heart leaf and leaf back spray. Severely deformed plants need to be artificially dissected to twist the heart.
The second is the Swedish stalk fly, also known as the stalk of black stalk. Since 1998, it has suddenly exploded on corn, and the damage has increased year by year in recent years. Its worm body is very small (the adult body is 1.5 to 2 mm long, black and shiny; the newly hatched larvae are as transparent as water, the mature larvae are yellow and white, and the damage is more concealed, and people are generally not easy to detect. After hatching, the larvae are drilled into the heart from the heart leaf joints, causing the tip of the heart leaf to be damaged, and the mucus secreted by it is stuck and cannot be unfolded, but the lower leaves continue to grow, so that the heart leaves form a taro or Ring shape. When the corn seedlings are damaged earlier and the growth cone is injured, it will form a “dry heart seedlingâ€; if the damage is late, the larva will only harm the edge of the heart leaf, and the leaves will form a “shrinkage†when they are unfolded, and the shiny mucus can be seen. trace. If it is not the formation of "dry heart", it does not have much impact on corn.
For these two pests, it should be prevented in the early stage, and the control effect of the drug after the corn leaf is curled is not good. The control methods are as follows: (1) coating the seed with a seed coating containing a component of a systemic insecticide . 2 3 to 5 days after the emergence of corn, 20% cyanoma emulsifiable concentrate 600 times solution, 22% chlorinated mixture 600 times solution, 1.8% avermectin 1000 times solution, etc., can be combined with the control of seedling corn borer, Myxostomy is treated once or twice. 3 Combine the seedlings and the seedlings, and manually break open or divide the heart-shaped leaves of the taro-shaped and ring-shaped corn seedlings that cannot be opened. 4 The plot with symptoms can be combined with the prevention and control of seedling pests, spraying trace elements to relieve symptoms, to promote robust growth of plants, and to increase production. 5 For plots with relatively dry and unfertilized fertilizers, watering and topdressing should be carried out in time to accelerate seedling growth.
4, top rot causes
Top rot can occur in any growth period of corn. The outermost leaves of the heart leaf tightly wrap the inner heart leaf, making it unable to unfold and whip. The leaves are deformed, shrunk or twisted. Rotting is often seen at the base of the heart. Corrosive or wet rot, with or without odor. For the prevention and treatment of corn top rot, 58% metalaxyl·manganese zinc wettable powder 300 times liquid, or 50% carbendazim wettable powder 500 times liquid, or 75% chlorothalonil wettable powder 500 times in the initial stage. Liquid spray, it is best to add a proper amount of zinc fertilizer spray to the liquid. For the diseased plants, it is best to unscrew the nozzles and align the corn leaf leaves from top to bottom, and spray 50-100 ml per plant.
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