How to do corn leaf rolling?
The main reasons for the occurrence of leaf curling in corn include high temperature and drought, improper application of herbicides, damage to thrips, and top rot disease. Production should carefully investigate the causes and take targeted remedial measures.
High temperature and drought
Different varieties have different adaptability to climate, and the ratio of heart leaf curling is quite different. The leaf curl of corn caused by drought in the field can generally recover gradually with the improvement of soil moisture, and recover quickly after rain or irrigation. Spraying some high-quality foliar fertilizers can promote rapid recovery.
Phytotoxicity
Herbicides such as nicosulfuron are used for weeding during corn growth, if corn seedlings are younger than 3 or more than 5 leaves, or if they are applied under high temperature conditions, or if they are applied excessively, or are applied organically within 7 days before and after herbicide application. Phosphorus pesticides, corn is prone to leaf curling, leaf shrinkage, accompanied by irregular yellow drug spots, serious heart rot. When the symptoms are mild, most of the plants will recover naturally, and the disfigured heart leaves can be manually disassembled. The timely fertilization and spraying of brassinolide and high-quality foliar fertilizers on damaged plots are beneficial to promote plant recovery.
Pest causes
There are two kinds of insect pests that cause the heart and leaves of corn to be rolled: First, corn is damaged by the thrips during the 3 to 5 leaf stage, and there are chlorotic dots on the leaves and the thrips are visible after peeling off the happy leaves. The use of nitenpyram, spinetoram, and other drugs can be used to control thrips, focusing on the heart blade and the dorsal spray. Seriously deformed plants need to manually dissect the twisted heart. The second is the Swedish stalk fly, also known as the rye stalk fly, which has suddenly exploded on corn since 1998. The damage has increased in recent years. Its body is very small (1.5 to 2 mm body length, black glossy; newly hatched larvae are as transparent as water, mature larvae yellow and white pods), and the harm is more subtle, people are generally not aware. After hatching, the larvae invade the heart and leaves and invade into the heart and leaves, causing damage to the tip of the heart and adhesion by the mucus it secretes. The larvae cannot continue to expand, but the lower leaves continue to grow, thus forming a heart-shaped leaf blade or Ring shape. Corn seedlings suffer earlier and injuring the growth cones, forming "dry dead seedlings"; if the damage is later, the larvae only harm the edges of the heart leaves. When the leaves expand, they will form a "wrinkle-like" and visible shiny mucus. trace. If it does not form a "dry seedling", it does not generally affect corn.
For these two kinds of pests, they should be controlled at an early stage, and the control effect of corn after curly leaves is not good. Control methods include: (1) Seeds are coated with a seed coating containing a component of a systemic insecticide. 2 3 to 5 days after the emergence of corn, use 20% Chrysanthemum EC 600 times, 22% Prochloroi mixture 600 times, 1.8% Avermectin 1000 times and other spray, later combined with control of seedling corn borer, Insecticides cure one or two times. 3 Combine with seedlings and seedlings to artificially break open or remove the bread-and-loop shape corn seedlings that cannot be developed. 4 The symptomatic plots can be combined with the prevention and treatment of pesticides during the seedling stage, and sprayed with trace elements to relieve symptoms, so as to promote the robust growth of the plants, and to increase the yield. 5 For the drought-bearing and unfertilized plots, watering and top-dressing shall be timely to accelerate the growth of seedlings.
Top rot causes
Top rot can occur during any growth period of corn. The outermost leaves of the heart are tightly wrapped around the inner heart and leaf, making it unable to expand and whip. The leaves are deformed, shrunken or distorted. Decay is often seen at the base of the heart. Corrosive or damp, with or without odor. Prevention of corn top rot, can be used in the early stages of the occurrence of 58% metalaxyl MnZn WP 300 times, or 50% carbendazim WP 500 times, or 75% chlorothalonil wettable powder 500 times Spray, the best solution to add zinc fertilizer spray. For diseased plants, it is best to unscrew the sprayer and spray it from the top to the bottom of the corn leaf, with 50 to 100 ml per spray.
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