How to prevent and treat potato late blight? Potato late blight can be said to be a worldwide disease. In order to effectively prevent the occurrence and development of late blight in potato production, some experts use the potato industry in Shuangliu Town, Kaiyang County as an example to explain the causes of potato late blight and comprehensive control measures. .
1 Cause of the disease
1.1 Climate
Potato late blight is a climatic epidemic disease, which is greatly affected by the climate. It is more serious in the rainy season, but it will be mild or not in the case of less rain and dryness. In the bud to flowering season, in case of rainy weather, the humidity is high, which is conducive to the occurrence and prevalence of the disease. For susceptible varieties, as long as the daytime reaches 20 °C, the relative humidity is above 95% and lasts for more than 8h, and the high-humidity condition of about 12°C at night can last for more than 13h, and the disease can occur.
1.2 Variety resistance
At present, the main varieties of potato are poorly resistant. For example, Feiruiqi, Early White, Atlantic, and Xiapudi have good quality, large planting area, and the scale of planting area is single. When the climate is suitable, it is beneficial. The prevalence of the disease.
1.3 Cultivation Management
The cultivation management is not in place, such as the poor ventilation conditions in the field, and the high humidity in the field is conducive to the spread of the disease. Potato planting, which leads to sufficient amount of bacteria in the field, soil bacteria, seed potato, etc., combined with the lack of soil nutrients in continuous crops for many years, is prone to the disease.
2 symptoms
Potato late blight is a whole plant type disease that infects leaves, stems and potato blocks, mainly affecting the top of the plant, mainly leaves. In the early stage of the disease, the leaves are water-stained small lesions, which become round and semi-circular lesions, white mold on the back of the leaves; petiole and stem, leaf and petiole joints, or brown on the stem Infection; the epidermis toughness becomes brown and becomes brittle. When the humidity is high, the lesions expand rapidly; under low-humidity and high temperature conditions, the lesions are brown and dry, and the white mold layer is not obvious. When the disease is severe, the leaves are dry and wilting, and the affected part is black with a burnt rot. Finally, the whole plant is wet and rot, with an alcohol smell. The potato chips were brown or purple-brown irregularly in the initial stage of infection, and there were depressions. The potato was soaked in water, browned and rotted, accompanied by a stinky smell.
3 Comprehensive control measures
3.1 Selection of resistant varieties
Cultivation of disease-resistant varieties is the most economical, environmentally friendly and effective measure for controlling potato late blight. In the southwestern region of Guizhou, it is possible to select CFK-69.1, I-1085 and other varieties with good yield and high yield from the International Potato Center for production. .
3.2 Sun-breeding, seed dressing
After the potato seeds are taken out of the kiln and turned in the sun for about 2 h, the rotten potatoes and the deformed potatoes are removed, and then the buds are placed in places with scattered light. When the buds grow and will grow full of buds, cut into pieces, leaving one or two buds per piece, weighing about 40 g, and then planting the ash or fine soil with metalaxyl ash according to the instructions.
3.3 Strengthening cultivation management
Choose potatoes with high topography, loose soil and well-drained land, and at the same time do drainage and drainage, reduce the humidity in the field, and reduce the occurrence and development of diseases. Avoid partial application of nitrogen fertilizer and appropriate application of phosphorus and potassium fertilizer. Promote high ridge cultivation, especially in areas with heavy rain and good sensation, it is best to use large ridge planting to thicken the soil layer to prevent the disease from infecting potato chips. Reasonable close planting, control plant length. Sowing at the right time, it is best to make the susceptibility period so that the buds are in the flowering period and miss the rainy season concentration period. Reasonable rotation, avoiding continuous cropping or interplanting with Solanaceae, Cruciferous, and prohibiting continuous cropping with tomatoes. Timely discovering and removing the central diseased plants and clearing out the plots to reduce the spread of Phytophthora infestans.
3.4 Drug control
(1) Chemical control. When late potato disease occurs in the field, it can be controlled by eugenol, and its control rate is 79.67%. During the stocking period, the control effect of fluorobacteria and downy mildew suspension (silfane) on potato tuber late blight is as high as 86.22%. Or 80% allicin EC + 80% mancozeb WP + 80% allicin EC + 80% mancozeb WP mixed with potato late blight control effect is best, the control effect reached 81.54%. When the late blight is outbreak, use 68.75% fluorobacteria and downy mildew suspension 60~75ml/667m, or 72% frost urea·manganese zinc wettable powder (Kelu) 0.1~0.15 kg/667 m to spray 30 kg of water.
(2) Chinese herbal medicine, biological control. Studies have shown that the 80% ethanol extract of Sophora flavescens, Fructus Lycii, and Galla Chinensis has a better inhibitory effect on Phytophthora infestans, and the inhibition rate can reach 78.1%. The therapeutic effect of Trichoderma sp. HNA14 strain on potato late blight can reach 51.4%.
The above is all about the introduction of potato late blight prevention and control measures, farmers who planted potatoes can read this article carefully!
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