What diseases need to be prevented and controlled during lotus root cultivation?
What diseases need to be prevented and controlled when growing lotus root? Please give an introduction. Lotus root is a high-yield, high-efficiency aquatic cash crop and a vegetable variety commonly eaten by the general public. It is widely cultivated in various regions, and with the adjustment of industrial structures in various places, its cultivation area tends to keep expanding. In recent years, lotus root diseases have become increasingly serious...
What diseases need to be prevented and controlled when growing lotus root? Please give an introduction.
Lotus root is a high-yield, high-efficiency aquatic cash crop and a vegetable variety commonly eaten by the general public. It is widely cultivated in various regions, and with the adjustment of industrial structures in various places, its cultivation area tends to keep expanding. In recent years, lotus root diseases have become increasingly serious and have become a major obstacle to the development of lotus root production.
I. Common diseases of lotus root
1. Lotus root rot, also known as black root disease or lotus root plague. It is the number one disease in lotus root production. It is generally prone to occur in old lotus root fields with shallow plough layers and shallow water and in continuous cropping fields, affecting lotus root formation and reducing yield. It is a lotus root disease caused by infection with the corm-like Fusarium fungus, mainly damaging underground stems, aboveground leaves and leaf surfaces. The leaves sprouting from diseased stems are light green in color, and brown drying begins from the leaf margins, with the petioles finally dying. The pathogen mostly invades through wounds, absorbing roots or growing points, and the pathogen spreads with flowing water irrigation.
2. Lotus root leaf blight is the second major disease of lotus root, and the pathogen is a pathogenic fungus of the genus Sphaerotheca. It mainly damages lotus leaves. Pale yellow lesions first appear at the edges of lotus leaves, then gradually spread toward the middle of the leaves, turning yellowish brown, and finally spread from the mesophyll to the veins until the whole leaf dies. High temperature and frequent rain favor the disease, and insufficient fertility in lotus root fields makes the disease severe.
3. Lotus root leaf spot mainly damages leaves and can sometimes also occur on petioles. It is caused by the pathogenic fungus of the genus Isariopsis.
II. Comprehensive prevention and control of lotus root diseases
1. Implement 2-3 year crop rotation. In particular, paddy-upland rotation plays an important role in reducing diseases.
2. Select disease-free seed lotus roots for planting. Seed lotus roots carrying bacteria are the main source of infection for rot. To prevent this disease, the key is to select healthy plants from disease-free lotus root fields as seed lotus roots to eliminate the source of infection. Before planting lotus roots, spray the seed lotus roots with a 800-fold dilution of 50% carbendazim or thiophanate-methyl, or a 800-fold dilution of 75% chlorothalonil wettable powder, then cover and seal them tightly with plastic film for 24 hours, and sow after drying.
3. Remove diseased plants. Thoroughly remove diseased plants and diseased residues from affected lotus root fields, and bury them deeply or burn them in a centralized manner. Before planting, apply 50-100 kg of quicklime per mu, which both sterilizes and cleans the field and accelerates the decomposition of organic fertilizer.
4. Reasonable fertilization. Base fertilizer should be mainly organic fertilizer, and the fertilizer must be fully decomposed. For soil with high acidity and strong reducing properties, lime should be applied heavily, and lime should be applied early and in large amounts. During the growing period, pay attention to the combined application of nitrogen and phosphate fertilizers. Where conditions permit, silicate fertilizer should be added, and supplemental application of trace fertilizers such as boron, zinc and molybdenum is recommended. Do not apply chemical nitrogen fertilizer alone, so as to improve the disease resistance of the plants.
5. Scientific water management. During the disease period, irrigate with deep water to lower soil temperature and inhibit pathogen reproduction. Lotus fields kept for seed should maintain deep water soaking every day; do not drain the water or do winter ploughing and sun-drying of the soil clods. Non-seed fields should, after harvesting lotus seeds, all cut the lotus stems and plough or dig lotus roots, and it is best to plant one season of winter crops. Even if no winter crop is planted, the field should still be ploughed and irrigated to soak the field, reducing bacteria carried by the soil and diseased residues.
6. Timely chemical control. At the early stage of disease, spray with a 600-800 fold dilution of 50% carbendazim wettable powder, or a 800-1000 fold dilution of 50% thiophanate wettable powder, or a 600-fold dilution of 50% carbendazim wettable powder plus a 600-fold dilution of 75% chlorothalonil. Alternatively, mix 500 g of the above mixed powder with 25-30 kg of fine soil, pile and seal for 3-4 hours, then scatter it into the shallow water layer under the lotus root crowns. After 2-3 days, use a 600-fold dilution of the above mixture, or a 800-fold dilution of 70% thiophanate-methyl, or a 200-fold dilution of carbendazim mixed with a 4000-fold dilution of "402", and spray the leaf surfaces or petioles 2-3 times in succession. This can effectively reduce or control the spread of this disease.
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