Today, there are farmers in Shandong consulting in the technical exchange group, the grape stem is brown necrosis, and the fruit grains under these brown fruit stems are all lost.
The photo sent by the fruit grower, the stem is brown, and the fruit grains fall
Looking at the pictures he sent, it can be seen that it is the brown blight of the panicle shaft, which the fruit farmer calls "rotten flowers", which is the most susceptible disease to infection during the flowering period of grapes. Mainly infected with the panicle shaft and fruit stem, when the disease spots surround the panicle shaft or small fruit stem for a week, the nutrient transportation below the disease part is interrupted, the buds or fruits shrink, dry and fall off, which has a great impact on yield and quality, generally reducing yield by 10%-30%, and reducing production by more than 50% in severe cases.
In actual production, grape house blight, gray mold, downy mildew, the same will harm the grape shaft and other parts, and grape shaft brown blight has similarities, prevention and control should be carefully distinguished, so as to achieve early symptomatic medication. Today we discuss the symptoms and identification, pathogenesis characteristics and prevention and control measures of panicle axial brown blight:
1. Field onset symptoms
Grape panicle shaft brown blight mainly harms young ears, and the onset period is generally before and after flowering - young fruit stage. At the beginning of the disease, light brown, water-soaked spots are produced on the epidermis of the young panicle stem or panicle shaft, and after 3-5 days, the young panicle axis becomes brown and soft rot, and then expands to other branch panicle shafts and main panicle shafts. After another 2-4 days, the ring shaft of the diseased spot is rotated, and the part below the diseased spot wilts and turns brown, and quickly withers and turns black-brown.
Especially in the humidity, the spots expand rapidly, and you can see the black mold layer, the entire panicle axis becomes brown and necrotic, and soon loses water and withers, but the side panicles and spikelets on the dry blight ears and the stiff flowers and stiff fruits are not easy to fall off, and the largest dry fruit grain on the diseased ears is 7 millimeters longitudinal and 5 mm in diameter. The dry inflorescence shaft is easily broken off by the wind at the branch, leaving a narrow and long dry scar on the spike axis. On these dry and diseased panicles, the morphology of different stages of growth from buds to young fruits can be seen.
A, c severe onset; b, d, partial onset
However, the onset of the disease in the young fruit stage - the expansion stage, the fruit grains will shrink and fall off.
Fruit grain atrophy and shedding (this picture is a mixture of powdery mildew and brown blight)
2. Distinguish from gray mold and house blight
Grape house blight, the color of the panicle shaft is closer to black, drying and shrinking, after the panicle shaft is rigid, the fruit grain becomes a black zombie fruit, which is not easy to fall off the vine and remains on the tree for a long time. It can be controlled by sprays such as apyroxyspecs, pyrazole ether esters, and diphenethoconazole.
Grapevine blight, fruit grain atrophy, black
Grape gray mold, the most obvious difference is that when the air is humid, the spots can produce rat gray mold, when the air is dry, the young fruit gradually loses water, shrinks, and then dries up and falls off, causing a large number of flowers and fruits, and when it is serious, the whole ear can fall out. The fruit is infected with gray mold and forms brown depression spots. It can be used with pyrimidine, putrex, isobacterium urea, azole. Fluoramide and other agents spray prevention and control.
Grape gray mold, fruit spike crevice gray spore pile
Grape downy mildew, mainly harmful to the leaves, when the humidity is high, the leaves have a white mold layer, the later mold layer turns brown, and the leaves fall early. After the flower spikes and young fruits are damaged, a white mold layer is produced in the affected parts of the humid environment, the flower spikes become brown, gradually rot and dry, and the young fruits first harden, then gradually brown, soften, dry up, until they fall off. Downy mildew can be controlled by sprays such as oleyl morpholine, pyrimicostate, 60% pyrazole ether ester and daisen water dispersible granules.
Downy mildew of grapes, flower spikes turn brown, white mold layer
1. The onset time is early and the course of the disease progresses rapidly
Panicle axis brown blight bacteria generally overwinter as conidia or mycelium on the mother grape branches or disease residues scattered in the soil, the next year, when the inflorescence is exposed to before and after flowering, during this period, if the rainy weather (temperature reaches 10 ° C - 25 ° C, humidity of more than 90%, the most susceptible to disease) the pathogen to conidia through the wound or natural orifice to invade the epidermal tissue of the panicle shaft, infection and spread, from the appearance of spots to the panicle dry withering only about 10 days.
2. The invasion of pathogenic bacteria is related to the variety, tree age, and the degree of old and tender fruit ears
Different varieties of grapes have certain differences in the resistance of grape panicle shaft brown blight. For example, the varieties that are susceptible to diseases are Giant Peak, Black Olin, Red Banana, etc., and the disease-resistant varieties are rose dew, etc.; the incidence of elderly trees is more serious, and the incidence of young trees (2-3 years old) is mild; pathogenic bacteria are only harmful to young ear shafts, and the higher the degree of lignification of the panicle shaft, the lower the incidence.
In addition, partial application of nitrogen fertilizer, light application of phosphorus and potassium fertilizer, fruit spikes close to the ground, etc. are prone to disease; orchards with mild onset in the north-south direction and heavy disease in the east-west direction; orchards with poor ventilation and light transmission on low-lying terrain, depressed and closed small environments with large humidity and poor management are more serious.
Panicle axial brown blight causes fruit grains to fall off
The incidence of grape panicle shaft brown blight is affected by climatic conditions and man-made factors, and eliminating the pathogen is the most effective way to prevent grape panicle shaft brown blight, so in the process of prevention and control of the disease, it is necessary to combine agricultural preventive measures and chemical control to control.
1. Agricultural prevention and control
Agricultural control is mainly divided into the following 5 kinds: one is to select disease-resistant varieties, such as red earth, rose dew, etc.; the second is to clean the orchard, remove the diseased branches and fruits of the orchard in time, after pruning in autumn, before the spring excavation, remove the old bark of dead branches and deciduous weeds in the garden, and burn them in a concentrated manner; the third is to wipe the buds and shoots. Timely smearing, heart-picking, pruning of fruit branches, improving ventilation and light transmission conditions, and minimizing damage caused by machinery; the fourth is reasonable fertilization, heavy application of base fertilizer, no partial application of nitrogen fertilizer, appropriate application of organic fertilizer and phosphorus and potassium fertilizer, so as to enhance the tree potential, enhance the disease resistance of grape branches and vines; fifth, timely drainage and humidification. For low temperature and rainy weather, it is very easy to cause diseases, and it is necessary to drain the accumulated water in the field in time and reduce the humidity, thereby weakening the conditions for the growth of pathogenic bacteria.
2. Chemical agent prevention and control
Chemical control is the most commonly used control method, because the disease is a disease that occurs in the early stages of grape growth, only endangering the young panicle shaft and stem, so the key period of spray control is from the grapes to produce the fruit panicle until the fruit expands rapidly.
Protective medication after grape sprouting: 70% methyl tolbucin wettable powder 1000 times liquid, 80% xenonium zinc 1000 times liquid, 50% pentazool 2500 times liquid, 40% pyrimidine suspension 1000 times liquid, 50% humus Lifmei double wettable powder 1000 times liquid, 80% Daisen manganese zinc wettable powder, 50% Fumei double wettable powder, 50% isobacterium urea wettable powder and other agents sprayed, has a good protective effect;
The inflorescence isolation period and 7 days after flowering, therapeutic medication: this period is the main period of invasion of grape panicle shaft brown blight, and it is also a critical period for prevention and control. It can be sprayed 2-3 times with 40% phenyl ether methylcyclazole 5000 times liquid, 250g/l azoxystrobin +40% phenyl ether methylcyclazole 1500 times liquid, 65% phenyl ether and ether ester 1500 times liquid, etc., with good control effect. In order to improve the efficacy of the drug, it is necessary to alternate the use of drugs to avoid drug resistance.
At present, grape panicle shaft brown blight has become one of the main factors affecting the yield and quality of grapes in our region, often causing serious losses to production. In addition, many farmers and even professional and technical personnel are basically unaware of the disease, and it is easy to miss the best prevention and control period, which seriously affects the prevention and control effect and the increase in grape production and income.
After the grapes flower, they begin to shift from vegetative growth to reproductive growth, the demand for nutrients increases, the tree is weaker, and it is susceptible to disease. Grape panicle shaft brown blight is very susceptible to disease at this time, and after the grape disease, a large number of flowers or young fruits dry up and fall, which has a great impact on yield and quality. Therefore, it is particularly important to prevent grape panicle shaft brown blight at this stage. It is recommended to take agricultural prevention and control as the basis, prevention as the mainstay, first of all, spray methyl tolbuzin wettable powder, 80% xenozyl zinc, 50% pentazolidol and other protective agents for protection, as long as the protection is good, you can inhibit the occurrence of the disease; once it occurs, seize the initial stage of the disease, use 40% phenylethmethicazole 5000 times liquid, 250g/l pyrimidine +40% phenyl ethermethicazole 1500 times liquid, focusing on the spraying of the disease site can be efficiently controlled.