Lettuce virus disease

Lettuce virus disease can occur throughout the reproductive period, the previous period of disease has a greater impact on the yield.

Symptoms: The whole plant is onset, and the incidence of seedling stage is mostly in the four true leaf stages. The leaves have uneven patches of mosaic mottled leaves, wrinkled and twisted leaves, sometimes appearing veins, and severe taupe necrotic lesions can also appear in severe cases. . Onset of disease, leaf shrinkage, foliar bulges are very uneven, plant growth is inhibited, obviously dwarf, severe brown veins or brown necrotic spots appear.
The pathogen is a virus. As many as 10 kinds of pathogenic virus, single or combined infection, including lettuce mosaic virus (LMV), dandelion yellow mosaic virus (referred to as DYMV) and cucumber mosaic virus (referred to as CMV) three virus-based.
The characteristics of the disease?? The three pathogenic viruses can be transmitted through the mediator aphids and sap, but the dandelion yellow mosaic virus juice transmission rate is low. Lettuce mosaic virus and dandelion yellow mosaic virus can also be transmitted through the seed. Its source of poison mainly comes from the field of lettuce, lettuce and other diseased plants, and the use of locust transmission, the incidence of seedling stage is mainly caused by the seed poisoning (Cucumber Mosaic Virus seed not transmitted). Peach moss has the highest transmission rate. Carrot pods, melon pods, and big larvae can also be used for transmission.
The occurrence and development of the disease is directly related to the weather. The average temperature is above 18°C, especially the high temperature and drought weather and prolonged lack of water are beneficial to the breeding and activities of locusts. Therefore, the disease is also developing rapidly and in serious condition. There is some difference in disease resistance among varieties. The general leaf-leaf type is more resistant than the ball-type variety; the heat-tolerant variety is also more resistant than the non-heat-resistant variety to the Emperor Bo (the United States cited), Caesar (Japanese cited, extremely early mature), the avant-garde 75 (the beautiful cited), the green wave (Japanese cited), Malak (external introduction, early maturing ball), Taihu Lake 366, red lettuce, sweet-vegetables, chicken cole lettuce, Cantonese lettuce (alias loose-leaved lettuce) and other performance than Bo?
Control methods
1. Select disease-resistant seed varieties according to local conditions.
2. Summer and autumn planting should cover the shade net, and take precautions to take cooling measures. Seedling stage (emergence period) pay attention to water pouring, avoid excessive seedlings. Pay attention to spraying foliar nutrient in an appropriate period to promote early growth of the plant. Diligently weed out field weeds.
3, do a good job of controlling phlegm and prevention of Bo? 1 in the locust when the spot occurred in a timely manner to kill the locust (50% anti-influence 2 000 to 3 000 times, or 40% gram star 800 to 1 000 times, etc.). 2 conditional use of silver film to avoid or yellow board deterrence. (4) spraying control Bo? The beginning of the onset of spraying 20% ​​of the virus A wettable powder 500 times, or 300 times the antitoxic agent No. 1 agent, or 83 agent (that is, 10% mixed fatty acid aqueous emulsion) 100 Double fluid, 3 to 4 times, once every 10 days.

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