Occurrence regularity and green prevention and control technology of grape gray mold

Occurrence regularity and green prevention and control technology of grape gray mold

Grape gray rot, commonly known as "rotten flower ear", is one of the most common and serious diseases in grape production, which is mainly caused by Botrytis cinerea. In recent years, the incidence of grape gray mold is increasing year by year, especially in the old grape producing areas. The prevention and treatment of the disease is difficult, the recurrence rate is high, and when it is serious, it will cause no harvest and bring serious economic losses to grape production. This disease should be paid great attention to by fruit growers.

1 harmful symptoms

Grape Botrytis cinerea mainly harms inflorescences, young fruits and ripe fruits, and sometimes new shoots, leaves and pedicels. Most of the inflorescences occur before flowering, and the inflorescences seem to be scalded by hot water at the initial stage, showing dark brown, soft rot of the diseased tissue, dense gray mildew layer on the surface, wilting of the killed inflorescences, and young fruits are easy to fall off; the fruit stalks are dark brown after being susceptible to the disease, and sometimes black massive sclerotia are produced on the disease spot. After the grape blossoms, the ear of the grape shows a light brown water immersion at the beginning, and soon becomes dark brown, and the whole ear is soft rotten. If it is overcast and rainy in this period, a light gray mildew layer will grow on the ear after 2 or 3 days. The fruit is susceptible to disease in the near mature stage, which first produces a light brown sunken spot, which quickly spreads the whole fruit and causes the fruit to rot. When the disease was serious, the whole ear or part of the ear rotted, the mouse gray mildew layer grew on it, the stem became black, and the black massive sclerotia appeared in the later stage of the disease. finally, the whole ear was covered with mildew layer and all the fruits rotted. New shoot leaves can also be susceptible to disease, resulting in irregular brown disease spots, which sometimes appear irregular wheel lines, and there are irregular gray mold layers when they are moist. Generally, each leaf has 2 or 5 disease spots, and in severe cases, the disease part can also grow rat gray mold layer, and finally dry up.

2 the regularity of the disease

Botrytis cinerea overwinters with conidia and sclerotia in diseased branches, bark and fruit. In the following spring, conidia formed to infect inflorescences and young leaves. Conidia spread to flower and young fruit ears by wind, rain and even air flow. The pathogen often lurks without disease after invasion, and infects when conditions are available, resulting in a pandemic. But in the middle of summer, with the arrival of the hot season, the disease ceased to spread until the temperature turned cooler. Botrytis cinerea has three peaks in a year, the first time before and after flowering, from mid-May to early June, it mainly harms flowers and young fruits, often causing inflorescence rot, drying and shedding, and further infecting ear and ear rachis; the second disease occurs during the fruit color change to maturity stage, the pathogen is most likely to invade from the wound, sunken spots appear on the fruit grain and ear axis, and soon the ear soft rot and pedicel turn black, forming a rat gray mold layer (figure 1). The third time in the process of postharvest storage, Botrytis cinerea will occur if not managed properly, and the disease will have obvious rat gray mold layer, resulting in ear rot and great loss. The onset temperature of the disease is 5: 31 ℃, the most suitable temperature is 20: 23 ℃, the air relative humidity is more than 85%, and the disease is serious when the humidity is above 90%.

In addition, the vineyards with extensive management, large amount of nitrogen fertilizer, insufficient phosphorus and potassium fertilizer, more mechanical and insect injuries, weak tree potential, low-lying terrain, more stagnant water after rain, long and closed branches, poor ventilation and light transmission are all conducive to the occurrence of Botrytis cinerea.

Fig. 1 symptoms of fruit damage during color conversion period

3Green prevention and control technology.

Green prevention and control technology refers to the behavior of taking ecological control, biological control, physical control and other environmentally friendly measures to control pests with the goal of promoting safe production of crops and reducing the use of chemical pesticides. Starting from the farmland ecosystem as a whole, on the basis of agricultural control, we should actively protect and utilize natural enemies, improve the resistance of crops to diseases and insect pests, and use chemical pesticides reasonably when necessary to minimize the damage of diseases and insect pests.

3.1 Prevention and control of cultivation techniques

3.1.1 strengthen the management of water and fertilizer, increase the amount of bio-organic fertilizer and potash fertilizer, and reduce the use of chemical fertilizer, using 500 kg of bio-organic fertilizer, 15kg of potash fertilizer, 10kg of compound fertilizer and 2kg of urea per mu. During the first fruit expansion period (adzuki bean grain size), the young grape fruit was fully expanded by watering once at intervals of 7-10 days, and the fruit expansion slowed down during the rainy season, reducing fruit cracking, thus reducing the occurrence of grape gray mold and other fruit diseases. It has better prevention and control effect. In the rainy season, the ground is covered with white transparent plastic sheet before the rain, and the drains are repaired under the cloth, which can drain in time after rain and reduce the humidity of the orchard (figure 2), which can effectively inhibit the infection and expansion of the disease.

Fig. 2 plastic sheeting on the ground can reduce humidity and increase fruit sugar content

3.1.2 coring and thinning to control the yield of grape at the early stage of pruning and panicle setting, a functional leaf is retained on the fruit branch to carry out the first coring of the branch, so that the nutrition is concentrated to supply the spike, which can naturally lengthen the spike and increase the length of the spike by 10% to 20%. The length of the spike can reach about 12 cm; the spikelet length is 3-5 cm, and about 15 spikelets are reserved for coring the whole spikelet (figure 3). When the auxiliary tip grows to 15 leaves, the second branch coring can be carried out, which can save labor and effort. The ruby variety has 150 grains per panicle, which can effectively reduce the appearance of large and small grains, the ear is cylindrical, the weight of each panicle is 500 × 800 grams, and the yield per mu is controlled at 1 500 ~ 2 000 kg, which can play a better role in preventing and controlling the occurrence of grape gray mold.

Fig. 3 keep a functional leaf coring on the ear

3.2 Prevention and control of agricultural measures

3.2.1 timely removal of diseased bodies and weeds, cutting off diseased branches and leaves, concentrated burning or deep burial, so as to reduce the source of overwintering bacteria. Combined with Qingyuan, the trees and the surface of the garden were sprayed with 3-5 Baomedo stone sulfur mixture or 45% (mass fraction) 200-fold solution in early spring to eradicate the overwintering bacteria.

3.2.2 increase the height of the grape to about 1.5 meters, make the tree ventilated and transparent, prevent the ground residue and soil pathogens from spattering on the fruit, and reduce the occurrence of diseases.

3.2.3 avoid intercropping other crops because of the wide host range of Botrytis cinerea, which not only harms grapes, but also harms more than 470 species of plants, such as strawberries, tomatoes, eggplants, cucumbers and so on. Such as intercropping other crops, it is easy to cause cross-repeated infection, cause disease pandemic, and increase the cost of control.

3.3 combination of biological control and chemical control

Ludikang 3, a biocontrol agent, is a beneficial endophytic bacillus isolated from healthy branches, leaves and fruits of grape. After indoor resistance screening to pathogens, and then to the field for disease control experiment, the effective strain with better performance was fermented by modern microbial fermentation engineering technology, which is a liquid bacterial agent with the efficacy of disease prevention, yield increase and quality improvement.

The mixed use of biocontrol agents and chemicals has played a role in learning from each other's strong points to offset their weaknesses. The bacillus selected in the biocontrol preparation can colonize and reproduce on the grape fruit and inhibit the infection of pathogenic bacteria. After mixing with chemical fungicides (except fungicides and copper preparations) and insecticides, Bacillus exists in the form of a dormant body. when sprayed on grape plants or ears, chemicals kill a large number of pathogenic fungi, and after the expiration of the fungicides, Bacillus propagates in large numbers on grape plants, thus inhibiting the invasion of pathogens and achieving a good prevention and control effect.

Botrytis cinerea of ruby grape occurred seriously in the grape base of Luyuan Fruit Industry Professional Cooperative in Shangshui County, Henan Province in 2016. the average ear incidence rate reached 65.6% in mid-July, resulting in serious losses. A demonstration of prevention and control of Botrytis cinerea was carried out in 15 mu of ruby grape in 2017. Ludikang No. 3 was mixed with chemicals and sprayed once at the sprouting stage, after blooming, at the young fruit stage and before bagging, respectively. Use motor sprayer to spray evenly on the grape tree. According to the investigation on August 30, the control effect of Ludi Kang 3 experimental area on grape gray mold was 44.4%, and the control effect of Ludi Kang 3 mixed with fungicides in the demonstration area was as high as 96.7%, and the control effect was significant [Jishan Huayao].

The green prevention and control technology was tested and demonstrated in the vineyard of Zhengzhou Agricultural Expo Garden in Henan Province, the New Century vineyard in Huailai County, Hebei Province and the vineyard in Yuanbaoshan District of Chifeng City, and achieved good results in the prevention and control of grape gray mold.