I. Infection of Grape White Rot The pathogen of Grape White Rot overwinters with mycelium and conidia on creeping plants or diseased fruits, leaves and thick skins scattered on the ground and subsoil, becoming the primary source of infection in the following year. In suitable natural environment, conidia germinate, spread by wind, rain and insects, and invade through branches, nectaries and, of course, nozzles. In the high and low temperature natural environment, germs can also invade from the drainage pipe and reinfect many times during the whole grape growth period, which is the infection cycle of grape white rot.
Second, the prevention and control measures of grape white rot From the infection cycle of grape white rot, it can be known that its infection epidemic is related to varieties, climate, planting management and other reasons. In order to effectively control white rot, we should grasp two key links, namely, reducing the source of orchard pathogens, cutting off the transmission route, enhancing the resistance of tree stems according to effective planting management, manipulating infection and disease standards, and spraying chemicals in time to achieve the purpose of efficient control.
1. Selecting and planting disease-resistant varieties is the most ecological protection and the most effective countermeasure. Eurasian species, such as "Beauty Finger", "Grape" and "Red Golden Finger", are one of the main grape varieties in China, but none of the classic Eurasian species is resistant to white rot. In pastoral areas where diseases are often prevalent, we should try our best to prevent planting or replacing susceptible varieties, and choose European and American varieties with strong resistance, good quality and high commodity rate, such as Kyoho, Red Earth, Xiahei, Victoria's Secret, Giant Star, Seedless Chicken Tun, Bletilla striata and Rattan Chicken, so as to control the occurrence of white rot.
2. Eliminating bacterial sources and reducing the number of white rot pathogens in the field are the basis for controlling white rot. Combined with autumn and winter pruning, the diseased body with germs is taken out of the orchard to carry out centralized disinfection and reduce the total number of overwintering germs; During the growth and development of grapes, the diseased fruits, diseased ears and diseased branches in the field should be removed immediately, and the diseased fruits should be tidied up and treated centrally outside the garden. In autumn and winter management, cut off the diseased branches again, peel off the thick skin, clean up the dry branches and dead leaves on the ground and destroy them.
3. Strengthen orchard management, improve its disease resistance, apply organic fertilizer, enrich soil layer, improve soil texture, promote more developed roots and stems of plants, and enhance disease resistance; Drain the pipeline immediately to ensure that the humidity in the park is not suitable for high temperature in summer, and it is forbidden to store water or wet roots in the field; Try to avoid unnecessary wounds and reduce the infection standard of germs.
Immediately wipe the bud, pick the top, tie the vine, pick the secondary branches, cut off the new branches and leaves that are too dense, and keep the orchard ventilated and transparent. In the work of thinning flowers and fruits, the flowering and fruiting load of plants should be effectively regulated according to the level of soil organic matter and the rising situation of grapes, so as to prevent the growth and development advantages and disease-resistant characteristics of grape fruit trees from being weakened by pursuing only perfect yield increase and excessive flowering and fruiting.
4. Chemical control Chemical control is the most important control strategy for grape diseases. However, considering the problems of environmental pollution and food safety factor, it is suggested to choose slightly toxic chemicals scientifically and reasonably according to the deterioration of the disease, so as to achieve high efficiency and environmental protection.
(1) Eliminating overwintering pathogens Spraying 3-5 degrees omethoate on branches, stems and ground before grape germination can effectively eliminate overwintering pathogens and prevent downy mildew, downy mildew and brown spot diseases. In orchards with serious diseases, it is suggested that soil disinfection should be done well before germination, and sulfur 1 serving, iprodione 1 serving and calcium bicarbonate 2/serving should be sublimated. After mixing, topdressing 1.5-2kg every two weeks, spraying 1 time, a total of 3-4 times, can achieve the actual sterilization effect. Note: it is best not to spray agricultural streptomycin, because white rot fungi have certain resistance to copper and cannot achieve good control effect.
(2) At the early stage of the disease, alternately spraying chemicals to control grape white rot. Many people use single or mixed agents, such as thiophanate methyl, mancozeb, mancozeb and so on. , make bacteria resistant. It is suggested that chemicals with different control effects should be selected alternately according to the disease condition, and the best time should be chosen (the incidence of grape white rot is in the range of 0. 1%-0.5%, which is the best time to control the disease). According to the experimental research:
Pesticides with control effect of over 90% are: 20% penconazole water solvent, 10% difenoconazole, 250g/l pyraclostrobin acetamiprid, 400g/l flusilazole EC, 25% propiconazole acetamiprid, 60% triazole ethylthiram, 30% triflumizole, 5.
The fungicides with more than 80% control effect are: 66.8% of Modoco (propineb+propineb) wettable powder, 60% of Baitai (pyraclostrobin+Daisenlian), 25% of Amisi suspension concentrate, 50% of iprodione, 22.2% of imazalil, 65,438+000% and 68. 50%-70% of the control agents are: 70% propineb wettable powder, 80% mancozeb wettable powder, 70% thiophanate-methyl, 75% mancozeb, etc.
Note: The control effect is relative. It is suggested that different chemicals should be selected alternately for spray control according to the drug use situation and illness condition in orchard, so as to improve the control effect and prevent bacteria from producing drug resistance.
3. It is concluded that grape white rot is one of the main diseases of grapes, which occurs in all grape producing areas in China and has an increasing trend. Its effects on grapes include reducing plant type, damaging branches, reducing yield and even leading to poor harvest. Effective control of grape white rot and reduction of the total number of white rot pathogens are the basis of control, and blocking the transfer of conidia is an important link in control of white rot. Therefore, before the arrival of high temperature and high humidity weather, spraying protective fungicides with general control effect in advance to prevent it, and effectively selecting fungicides according to the severity of the disease after the onset can significantly reduce the incidence and severity.
Share a tip: The practice of many fruit farmers shows that covering the ground with waste plastic film in early spring can effectively prevent the initial infection of white rot fungi, and at the same time, it is convenient to clean the diseased leaves and fruits cut by wiping buds and thinning fruits, which is beneficial to rural cleaning, and even in seriously ill fields, it can greatly reduce the incidence and severity of that year.