How to scientifically prevent and control potato late blight? These methods you need to master
The potato, of the Solanaceae family and Solanum genus, is an annual herbaceous plant, also known as di dan, yang yu, tu dou, and so on. The earliest artificial cultivation of the potato can be traced back to approximately 8000 to 5000 BC in the southern region of Peru. It originated in the area of Peru and Chile in the Andes mountain region of South America. The Lake Titicaca area, at over 3800 m in the Andes, may be the place where the potato was first cultivated. About 7000 years ago, a tribe of Native Americans migrated from the east to the high, cold Andes, camped near the Lake Titicaca area, and lived by hunting and gathering; they were the first to discover and eat the wild potato.
The potato prefers cool conditions and is a crop that likes low temperatures. The formation and growth of its underground tubers require a loose, airy, cool and moist soil environment. Its temperature requirements: the suitable temperature for tuber growth is 16°C~18°C, and when the soil temperature is above 25°C, the tubers stop growing; the suitable temperature for stem and leaf growth is 15°C~25°C, and growth stops above 39°C.
The potato is rich in dietary fiber, which helps promote gastrointestinal peristalsis and clear the intestines.
In addition, potato tubers also contain carotene and ascorbic acid, which cereal grains do not have. From a nutritional point of view, it has more advantages than rice and flour, can supply the human body with a large amount of heat energy, and can be called “the perfect food”. A person can maintain life and health on potatoes and whole milk alone. This is because the potato's nutritional composition is very comprehensive and its nutritional structure is also relatively reasonable, with only slightly low levels of protein, calcium and vitamin A; and this is exactly what whole milk makes up for. Potato tubers are high in water, low in fat, and quite low in calories per unit volume; their vitamin C content is about 4 times that of apples, their B vitamins are 4 times that of apples, and their various minerals range from several times to several dozen times those of apples. The potato is a blood-pressure-lowering food; in the diet, too much or too little of a certain nutrient can cause disease. By the same reasoning, adjusting the diet can also “eat away” the corresponding diseases.
The potato has anti-aging effects. It is rich in vitamin B1, B2, B6, pantothenic acid and other B vitamins as well as a large amount of high-quality cellulose, and also contains trace elements, amino acids, protein, fat and high-quality starch and other nutritional elements.
Scientific Prevention and Control of Potato Late Blight
Potato late blight has occurred to varying degrees over the years, seriously affecting the improvement of potato quality, yield and economic benefits, so the prevention and control of potato late blight is extremely important. Potato late blight, also called blight, is a widespread and serious epidemic disease. It occurs in all areas where potatoes are grown; when late blight is epidemic, field yield losses of susceptible varieties can reach 20%-50%, and storage losses range from 5%-10% in mild cases to more than 30% in severe cases. Late blight not only harms potatoes, but can also harm tomatoes, peppers, eggplants and so on.
Symptoms of Potato Late Blight
The leaves, petioles, stems and tubers of the potato plant can all be infected and damaged. In the early stage of leaf disease, dark green water-soaked spots appear at the leaf tip or leaf margin; when the weather is humid, the lesions expand rapidly, and a circle of sparse white mold rings forms at the edge, especially noticeable on the underside of the leaf. In severe cases, the lesions extend to the main vein and petiole, causing the leaves to wilt and droop. When the climate is dry, the lesions dry up and turn brown. When the stem is damaged, slightly sunken streaks initially appear, and when the climate is humid, white mold also forms on the surface. When tubers are damaged, light brown or grayish-purple irregular lesions form, slightly sunken, and the flesh of the tuber below turns brown. When the soil is dry, the diseased part hardens and shrinks; when moist, white mold can also grow.
Potato late blight mainly damages leaves, stems and tubers. After onset, the area and number of leaf lesions increase rapidly, causing the plants and even the entire field of potatoes to die early in patches, and causing tuber rot, seriously affecting yield. This year our county has a large autumn potato planting area, and the growth is generally good; combined with the reality that Shizong has continuous autumn rain, low temperature and high humidity, and large day-night temperature differences over the years, potato late blight is prone to occur.
Prevention and Control Methods for Potato Late Blight
1. Breeding and promoting disease-resistant varieties: Choosing disease-resistant varieties is the most economical and effective way to prevent and control late blight. Different potato varieties differ greatly in their resistance to late blight, because the potato late blight pathogen is prone to mutation, and after several years of cultivation, vertical resistance varieties easily lose their disease resistance, so multi-gene resistant varieties or horizontal resistance varieties should be selected.
2. Establishing disease-free seed fields and eliminating the primary infection source: Since diseased seed potatoes are the only primary infection source, establishing disease-free seed fields can greatly reduce the primary infection source, thereby effectively preventing the occurrence of late blight. Seed fields should adopt stricter prevention and control measures. Where conditions permit, seed fields should be more than 2.5 km away from the main fields, so as to reduce the chance of pathogen transmission. In addition, selecting disease-free seed potatoes can also reduce the primary infection source, and chemical seed soaking can kill pathogens inside the seed potatoes, delaying late blight occurrence by 20 days and reducing the disease index by about 50%; for 100 kg of sprouted pieces, use 100 g of 25% metalaxyl, add a small amount of water, and dip or spray.
3. Strengthening field management: 1) Prepare the land, choose high terrain and plant where drainage is good, adopt measures such as intertillage management, hilling, removing tobacco roots, and opening ditches for drainage, and increase potassium fertilizer to improve disease resistance. 2) Before sowing, carefully select seed potatoes and eliminate pathogen-carrying tubers, which can reduce the number of central diseased plants in the field. Hilling in the later stage of potato growth can reduce the chance of zoosporangia infecting tubers. In epidemic years, properly cutting the vines early and harvesting after 2 weeks can avoid the chance of tubers contacting diseased plants and reduce the tuber infection rate.
4. Chemical control: In the early stage of late blight occurrence, promptly find and remove diseased plants, and spray chemical agents on plants within a range of 30-50 m around the central diseased plants, then spray once every 7-10 days as the situation requires, generally spraying 2-3 times, with a very good control effect. Drug options include 58% metalaxyl mancozeb, 64% sandofan, Daconi M-45, 72% DuPont Curzate, 69% Anchor mancozeb, and so on. In order to reduce the development of pesticide resistance, it is best to use multiple agents alternately.
In summary, potato late blight is a devastating disease with serious harm. The prevention and control of potato late blight in our county should be carried out in accordance with the guideline of “prevention first, comprehensive control”. Only by taking agricultural control as the foundation, chemical control as an auxiliary, and comprehensively applying multiple control measures can a good control effect be achieved.