Recently, some farmers have complained that the twists and turns of summer corn in some places cannot be unfolded. They are seriously presented as "cow's tail" or "big whip" and asked how it is solved. On this issue, Shao Lixia, a senior agronomist at the Longyin County Bureau of Agriculture, conducted a special investigation and conducted prevention and control experiments in this area. Now ask him to answer the reader's questions.
Nowadays, the summer corn in the maize production area of ​​the central and southern provinces of our province has entered the big bell-mouth period, and some plots have appeared inconceivable that the heart and leaves of the corn are not able to be distorted, and are severely presented as “cow tails†or “big whip†shapes.
Body> First, the main reason
1. Hummer, Swedish fly damage. Peeling the outer leaves revealed that the base of the leaf had shrunk and had holes. The main performance is the distortion of the heart and leaves of the corn, the leaves are damaged, shrunk, and rows of holes appear on the leaves. There is a transparent film on the front of the leaf, some of the heart has mucus, and some of the heart has been broken. The main reason is the damage caused by the thrips or Swedish fly during summer 5-6 leaf stage. According to our investigation on July 8-11, some plots of summer corn have 500 to 1000 heads of hummer, and some of the corn leaves are yellow, and the severe leaves are distorted. Some plots of summer maize leaves have silvery white spots, or deformed or broken leaves, which cannot be unfolded, twisted into "cow tails", and grow into tillers to form long lines. It is lighter to coat corn seed or planting fields, lighter fertilizers and pesticides are more serious. What stands out is that the hummer and the Swedish fly are harmful to the heart and produce mucus, causing the heart to fail to unfold properly and twisting into a "cow tail" shape.
2. Post-emergence herbicide injury. Damage to leaves of fleas and swarts was more or less impaired, as the twisted leaves were not damaged due to the use of nicosulfuron-containing post-emergent herbicides. According to a survey conducted on July 20, 20% of corn fields suffered phytotoxicity. The performance is a serious dwarf, the heart is distorted, it cannot be unfolded, and there is a phenomenon of childbirth. Some are distorted corn leaves, rotten hearts, yellow leaves, growing weaker, corn plant height is not less than the injury, rolling leaf strain rate of 10%. One of the reasons is that the purity of nicosulfuron made in China is not enough, causing phytotoxicity. Some are due to spraying at high temperatures or repeated spraying can also cause phytotoxicity. There is the age of corn more than 5 leaves, liquid medicine can not be sprayed into the heart, such as the accumulation of liquid medicine in the heart, can cause distortion, leaves turn white or rotten heart, the plants will dwarf. Then, because the herbicide is applied too late, the corn will cause phytotoxicity of the onion tube leaf, mainly because some hybrid varieties are sensitive to the drug and cause this symptom, resulting in the failure of normal panicle extraction.
Second, control methods
1. Immediately use scissors to cut off the upper 1/4 blade, or manually dismantle the twisted heart, and fertilize the water, spray foliar gibberellin (90%), the amount of application is 1 gram of water 15 ~ 30 kilograms, or spray 1,000 times the plant growth regulator "Tianfengsu" (brassica lactone), or efficient foliar fertilizer "double effect king", 1 bag of 40 ml of water to 30 to 45 kg, or 6000 times Love more than +0.2% to 0.3% of potassium dihydrogen phosphate +1% urea solution + zinc, boron fertilizer, 5 to 7 days 1, and even spray 2 times.
2. If it is caused by insect pests, it is mainly necessary to prevent and control the thrips and Swedish flies in the summer when 5 to 6 leaves of the corn are grown. In the period of large corn flares, spraying and preventing the disease are also required. Formula is: 10% imidacloprid 1000 times or 5% acetamiprid 1500 times plus agricultural streptomycin 500 ~ 800 times liquid, plus some gibberellin or high efficiency foliar fertilizer, spray 5 to 7 days intervals , spray twice.
3. Due to herbicide harm caused by distortion of the heart, it should pay attention to the use of high-quality post-emergence corn herbicides, and pay attention to avoid high-temperature time medication, the appropriate period of time to prevent drug use caused by drug damage too late.
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