What to do with mulberry brown spot in mulberry planting
Mulberry brown spot disease, also known as rotten leaf disease, focal spot disease, and plaque disease, is one of the main diseases of the mulberry leaf. Mulberry brown spot disease is a fungal disease, and the pathogen is a fungus of the genus Aspergillus spp. The silty mass on the lesion is actually the conidia disk of the pathogen, and the slightly reddish sticky powdery substance is the conidia of the pathogen.
Mulberry brown spot disease only harms the leaves, and more occurs in the young leaves. The lesions appear on both sides of the leaves. At the beginning of the disease, water-spotted spots with the size of the needle tip can be seen on the front and back of the leaf. The leaf color around the lesion is slightly yellow, and the contour is very obvious when the light is seen. As the disease progresses, the lesion gradually expands to form a nearly round brown tea. Or dark brown lesions, if restricted by veins, form a polygon or irregular shape.
In the late stage of the disease, the lesions are about 2-10 mm in diameter. The edges of the lesions are dark brown or brown in color. The center is light brown or gray, and small white or reddish powdery patches are scattered. This silty mass is present on both the front and the back of the same lesion, and finally becomes dark brown and remains on the lesion. In the late autumn, the periphery of the lesion usually has a purple-brown halo, and the veins are dip-dyed to become purple-brown, and the leaf back is more obvious.
When the weather is rainy and wet, the lesions swell and swell, and then rot and perforate; in the dry weather, the center of the lesion is often cracked. On the severely affected leaves, many lesions can be connected to each other into large lesions, and soon the leaves are scorched, forming "focal spots" or "rotten leaves" and falling off. Such as petiole, new shoots onset, it is dark brown, long-shaped slightly depressed lesions.
Prevention and control of mulberry brown spot disease should be carried out from the aspects of eliminating pathogenic bacteria, improving cultivation techniques and management of fertilization, and actively implementing the principle of “prevention first and comprehensive preventionâ€.
1, variety. Choose varieties with strong disease resistance, such as Husang 32, Husang 197, Nongsang 12, Nongsang 14 and so on.
2. Improve cultivation techniques and strengthen management of fertilization. First of all, when planting mulberry trees, it should be reasonably densely planted, and the mulberry gardens with low sorghum and moisture should be drained in time. At the same time, strengthen the mulberry field farming and weeding work, in order to promote the mulberry garden ventilation. Secondly, fertilization should be based on farmyard manure and organic manure. Since most of the silkworm areas in Yunnan Province are red soil acid soils, phosphorus and potassium deficiency are common. Therefore, when applying chemical fertilizers, phosphorus and potassium fertilizers should be rationally added according to actual conditions. The conditions can be scientifically fertilized after the soil testing formula, thereby enhancing the disease resistance of the mulberry tree.
3. Reduce the presence of wintering pathogens. This is the most direct and effective way to prevent mulberry brown spot. When conducting mulberry garden winter management, the ground should be turned over 1 time (depth 30-40 cm). After deep turning, the pathogens should be fully exposed and exposed to sunlight to reduce the density of pathogens. At the same time, in addition to the weeds in the mulberry garden, pick up the fallen leaves on the ground and remove the damaged leaves (this should be done before the leaves) and incinerate them in a unified way. When pruning in winter, the diseased branches, weak branches, dead branches, and insects should be wounded. The branches are also cut off and burned. For example, when a large number of diseases occur during the mulberry growing season, the diseased leaves should be removed in time and buried in a unified manner to reduce the proliferation of pathogenic bacteria.
4. Strengthen disease prediction and forecasting. Take reasonable and effective chemical control. All localities should establish long-term effective disease prediction and forecasting work according to actual conditions, and do so in a targeted manner. At the same time, effective drugs should be used for unified prevention and control (ie, uniform drug and concentration, unified spraying time), and the disease should be controlled within the effective range. Specifically:
(1) In the severely affected areas, the mulberry garden sprays Bomei 4-5 degree stone sulphur mixture, the time is carried out before the mulberry spring germination, or after the autumn silkworm is finished, it is sprayed 1-2 times with 0.7% Bordeaux mixture.
(2) In the prevention period, in the area where there is a large outbreak of mulberry brown spot disease, use 50% carbendazim WP 1000-1500 times before the spring silkworm rearing (pay attention to add 0.5 ‰ washing powder as a spreading agent) The effect is better. Spraying once can provide a good preventive effect.
(3) In the early stage of the disease, it can be sprayed with 50% carbendazim WP 1000-1500 times or 70% thiophanate WP 1500 times, and then sprayed once every 10-15 days, the condition can be well controlled.
(4) In severely affected areas, 50% carbendazim WP 1000-1500 times solution, 70% thiophanate WP 1500 times solution or 65% daisen zinc WP 2000 should be used in time after each sericulture. Spray the mulberry garden with the liquid.
In short, mulberry brown spot disease is one of the main diseases of mulberry gardens, and its harm and impact are obvious to all. We can only take control of the characteristics, diseases and pathogenesis of pathogens and take scientific and effective methods to prevent and control. The stable production and high yield of the leaves lay a good foundation for the production of silkworms.
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