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Grape downy mildew is serious, what is going on? Is there any way and pesticide can be used as a controlling method?
What is downy mildew
The yellow chlorosis on the front of the leaf is restricted by the veins of the horn, and the white frosty mildew appears on the back of the leaf. The mildew both on the spike and the fruit surface.
What is downy mildew, use a needle to pick a little bit and put it under the microscope.
Under the microscope, look at it again. This is the zoosporangium. After the mature rupture, the zoospores can be released. As long as the conditions are suitable for zoospores, they can germinate into the leaves of the buds or in the epidermis of the young fruit.
Causes of serious downy mildew
Improper management measures in the early stage:
The current prevention and control measures are not in place:
How to prevent it?
1. The blade has been seriously ill, needs to quickly control the disease. The fungicide with the main treatment of internal absorption mixed with protective fungicide;
2, the disease is not very serious, need stable and continuous control, mainly based on protective fungicides:
Because dimethomorph is a therapeutic agent, it is not suitable if you are taking enoylmorpholine at the time of prophylaxis, and you should use a broad-spectrum agent for prevention.
If you use the above methods are not very useful, you can try 45% azole ether. Tebuconazole suspension, and 30% pyroether. Methylthiolate suspension not bad.
Pay attention to the uniformity of the liquid blending and the coverage of the spray.
1. Note on dispensing liquid: High concentration does not mean high efficacy. The dilution factor should be determined according to the type and performance of the spray device and the growth of the grape. The traditional high pressure sprayer (machine) needs a larger amount of water to ensure High coverage, large dilution ratio, generally diluted according to product specifications or technical regulations. In addition, first use a small amount of water to open a preparation and then pour into the next preparation to open, it is not appropriate to pour several preparations and then stir together;
2, pay attention to coverage of pesticides solution: blending and spraying pesticide is using the least water to solve the agent as much as possible and cover the leaves or young fruit, because the distribution of pathogens on the plant is dispersed, and only the liquid completely cover the leaves and fruits would have better control effect. Therefore, it is necessary to ensure that the fight is evenly sprayed and covered. If the amount of liquid is not good, it will not be evenly sprayed. The long time of spraying the liquid will cause the liquid that has reached the leaf surface to flow down, and the final effect will not work. Flexibly master and use according to the performance of the device
Increasing the ventilation and transparency of the orchard, or increasing the density of the leaf epidermis, can also effectively reduce the disease.
1. Beat off the old leaves and dead leaves;
2, appropriate use of trace element regulators, such as: full feeding;
3, even the orchard that has been picked can not ignore the prevention and control of downy mildew, otherwise it will continue to suffer next year。