Occurrence and Prevention of "Diminutive Diseases" in Summer Maize
Corn "rough shrinkage disease", also known as "evergreen", from mid-May to July each year, spring corn and summer corn have different degrees. Through the survey and statistics in recent years, summer maize in the Huaibei Plain is extremely prone to occur. Those who suffer from "rough shrinkage" will reduce their output of corn, but they will suffer no harvest. First, the symptoms of suffering from "rough shrinkage" of the summer corn stalk atrophy became thicker, few spikes and sticks, branches dark green, abnormal leaves, dark green color. The diseased branch plants are shortened between the nodes, and the xylem of the diseased plant roots is dark brown in color, so it is also known as "evergreen". A few knotted spikes have only a few tens of grains of corn and are not well developed and uneven. Acute wilting disease often occurs after rain. Daejeon has the characteristics of combination of individual disease and population morbidity. Second, the incidence of the law "rough shrinkage" is mainly caused by transmission of poisonous insects and other causes, such as Laodelphax striatellus spread. The cultivated area of ​​susceptible varieties is large, the parasitic pathogens are found in seeds and soil, the humidity in the field is large, the temperature is between 20-35°C, and the density of the slugs is high, the condition worsens, and the infection spreads. Third, the prevention and control methods 1. Selection of disease-resistant varieties of disease-resistant varieties of planting is the prevention and treatment of "rough shrinkage" the most simple, economical and effective methods. The commonly used high-yield, stable-producing, and disease-resistant varieties include: Ludan 50, Ludan 98, Yuyu 22, and Nongda 108. 2. Rotation of crops in exchange for crops with severe disease in previous years may be carried out for another year in other crops to eliminate the source of the original pathogen or allow it to naturally die. The following year the maize will be planted again. 3. Reasonable Arrangement According to the survey, from late June to early July every year, it is the high incidence period of Laodelphax striatellus and aphids. Reasonably arranging gargles and cutting off the route of transmission is a good way to prevent the occurrence of "rough shrinkage." In order to avoid the peak period of disease infestation, production can be planted in advance by intercropping maize or transplanting with seedlings. When the height of locust infestation and locust infestation occurs, the summer corn has grown robustly, greatly improving its own resistance to diseases and insect pests and resistance. Infection ability. 4. Strengthen cultivation and management In addition to self-resistance, maize must also be strengthened in cultivation and management to remove stubborn strains of diseased fields and control the source of infection. Apply basic fertilizers, increase phosphorus and potash fertilizers, and increase resistance to disease. Before seed sowing, uncoated seeds can be sterilized with 75% chlorothalonil 200 times solution or 20% virus A 400 times liquid. At the same time, the rainy season did a good job of clearing the ditch, draining water, and cultivating the crops. There was no room for germs, slugs and locusts. 5. The chemical prevention and control at the early stage of disease, or the density of hoppers and locusts in each plant is more than 50 times. Can be used 25% triadimefon 2000 times or 70% thiophanate-methyl wettable powder 800 to 1000 times with 40% dimethoate 1000 to 1500 times mixed spray. At the same time plus 0.2% potassium dihydrogen phosphate solution and 1% urea solution, spraying leaves once every 3 to 5 days, and even spray 2 to 3 times, the control effect is good.