About once a day, use a fungicide! The ultimate control of grape downy mildew
Grapes are afraid that no one does not know downy mildew, it is harmful, rapid outbreak, difficult to control. When encountering a suitable climate, and not saying that it is raining, that is, when the dew is slightly larger, it is very likely to erupt. The degree of terror is evident.
In recent years, the resistance to downy mildew has risen rapidly, and the hazards have been increasing year by year. The way of infection is innovation, which really makes people headaches! The life of downy mildew
The pathogen of downy mildew is Plasmopara viticola, belongs to the order of flagellin, oomycete, downy mildew, uniaxium, and is a parasite. The mycelium spreads and spreads among the host cells and extends into the host cells with a nodule sucker to absorb nutrients. The damage of downy mildew is the most common form of damage on the leaves. Do not think that it only damages the leaves. Such as young shoots, tendrils, petioles, inflorescences, cobs, fruits, etc., but all the young green tissue, are deeply harmed!
Leaf damage
After the leaves were invaded, they initially showed semi-transparent, oily spots with unclear edges, which in turn often combined with large lesions, mostly yellow to brown polygons.
When the weather is wet or the humidity is too high, a white layer of downy mildew is formed on the back of the lesion. The late lesions were brownish and the leaves were easy to fall off early.
Tender damage
After the young shoots were damaged, water-stained spots formed, and later turned brown, the spots were slightly sunken. When wet, the lesions also produced white downy mildew.
When the disease is heavy, new shoots are twisted, growth stops, and even death occurs. Tendril, cobs, and petioles can sometimes be harmed, and their symptoms are similar to those of young shoots.
Inflorescence victim
The buds turn dark brown after being affected, and the surface is covered with white moldy material, causing wilting and shedding.
Young fruit victim
After the young fruit was infected, the disease department faded, became hard and subsidence, and a white downy mildew layer grew, and the diseased fruit immediately fell off.
Fruit enlargement damage
When the fruit enlarges, it suffers a brown soft rot. It will soon shrink and fall off, and the fruit will not be infected after being stained.
Recently, there have been various degrees of “black granules†in many regions, in part because of infection with downy mildew.
Aspergillus on the fruit, the more obvious feature is the first incidence of fruit stalk and fruit at the junction, and then the fruit brown sag, the phenomenon of more serious grain dropping.
In addition, physiological causes also accounted for a portion. Such as burning, lack of boron, improper fertilizer, water, etc. will also cause the fruit surface and the pulp black.
Worse yet, it is a combination of diseases caused by the combination of physiological diseases and downy mildew.
In any of the above situations, attention should be paid to improving tree vigor, strengthening field management, removing diseased grains in time, and preventing and controlling diseases such as downy mildew, white rot, and gray mold.
Prevention of downy mildew
From the incidence of downy mildew in recent years, there are two characteristics, one is getting older and the second is getting heavier! Although there are weather factors, improper management measures are the main reason.
Therefore, for the prevention and control of grape downy mildew must be to cultivate the tree for the purpose of preventing the main continuity of prevention and control measures.
Clear Garden
The downy mildew is a powerful measure to destroy the source of overwintering bacteria as the diseased branches, diseased fruits, and diseased leaves land into the soil for winter.
Breeding a robust tree
Reasonable water and fertilizer, strengthen management, promote the growth of the tree robust and not prosperous, really achieve the golden mean tree, and strive to improve the tree's disease resistance.
Demand water critical period: before sprouting, before and after flowering, color changing period, mature period, buried in cold weather.
The critical periods for fertilization: budding, fruit enlargement, color change, harvesting, and pre-wintering. Pay attention to the application of organic fertilizer, according to the grape's demand for nutrient elements under the fertilizer, in conjunction with sea elf bio-stimulant to achieve balanced nutrition, promote root growth, improve the soil environment, stimulate plant wild and other multiple effects.
Strengthen management: Do a good job of orchard drainage, control leaf shoots in summer with reasonable leaf screen, cut off unnecessary vine leaves close to the ground, pay attention to thinning and binding vines in time, and reduce the initial infection of bacteria from above-ground leaves. The diseased leaves and diseased fruits were found to be removed in time, concentrated and buried. Chemicals control Prevention and treatment of downy mildew in the rainy season should be controlled in a standard manner, that is, once in 10 days, a fungicide should be used. Generally, protective fungicides are mainly used.
The common protective fungicides are copper preparations (boron liquid, quinoline copper, copper rosinate), mancozeb, ketodazole, cyazosulfab, pyraclostrobin and so on.
Copper preparations, mancozeb: It is not safe to use before bagging and it is easy to cause injury.
Ketetanbuxol: Both white downy mildew are effective, have a good shelf life and do not hurt fruit powder.
Cyazofamidazole: high activity, long duration, no obvious resistance. Defects are narrow bactericidal spectrum and general conductivity.
Pyraclostrobin: Can only be used as a preventative. Cannot be mixed with silicone or cream products.
Pay attention to the use in advance, and be even and thoughtful when spraying, especially the back of leaves.
At the beginning of the disease, the prevention and treatment center focused on prevention and treatment.
Common therapeutic bactericides include metalaxyl, cymoxanil, propamocarb, dimethomorph, fluorothiazolpyridone, carbazide, fluoproxil, and chlorobromoisocyanuric acid.
Metalaxyl, cymoxanil: Faster results, safer use, but shorter effective period, it is recommended that it be mixed with protective agents.
Proplocarb: good absorption, good safety, general bactericidal activity, high concentration must be used to achieve control effect.
Dimethomorph: The resistance is obvious, and the concentration must be increased to ensure the control effect.
Fluthiazolpyridone: fast-acting type, long-acting properties are very good, but the single point of action, the role of resistance to Peronospora is not obvious, it is recommended to prevent the main.
Fluopyram: Absorbing block, resistant to rain erosion, suitable for rainy season.
Carbazole sulfonamide: kills resistant mutants of downy mildew for a long duration.
Chlorobromoisocyanuric acid: Efficient and broad-spectrum, but with a short duration of efficacy. It is recommended that the disease be used during the outbreak and mixed with other protective agents.
Spraying can be used first with a contact bactericide to destroy the fungus on the back of the diseased leaf, then spray the therapeutic bactericide, and finally use a protective bactericide to consolidate the effect.
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