Why is Botrytis cinerea difficult to treat? How to prevent and cure?

Frequent continuous rainfall and relatively low temperature in the greenhouse create favorable conditions for the occurrence and spread of Botrytis cinerea. Grape gray mold, cucumber gray mold, tomato gray mold, strawberry gray mold, eggplant gray mold, leek gray mold and so on, no matter which kind, are very difficult to control. Farmers often complain that once Botrytis cinerea occurs, even if all available fungicides are exhausted, even the specific fungicides specifically used to control Botrytis cinerea will not work. Why is Botrytis cinerea difficult to treat? How to prevent and cure gray mold?

First, why is gray mold difficult to treat?

1. The germs propagate rapidly.

The reproduction rate of the pathogen is fast, and the number of spores is amazing. The reproduction rate of Botrytis cinerea is very high. The English name of Botrytis cinerea is "botrytis", which means "grape ear". Its conidia (the grayish-brown mildew on the susceptible parts) are like grape ears under a microscope, with an astonishing number.

2. The viability of bacteria is very strong.

Botrytis cinerea has strong adaptability and survival ability. It can not only absorb nutrients from living plant tissues, but also survive in dead remains. It belongs to semi-living nutritional bacteria. Taking Botrytis cinerea of cucumber as an example, the conidia of the pathogen could survive on susceptible fruits, petals, calyx, stems and leaves for 4 to 6 months, and the sclerotia survived longer. Botrytis cinerea can survive in the soil, on the plant, on the back wall of the greenhouse, on the post, on the hanging line, and spread to the plant through air flow, Rain Water, farming operation and so on. Once the conditions are suitable, it will germinate and infect rapidly.

3. Germs are easy to invade from the wound

The pathogen of Botrytis cinerea likes to be "sweet and tender", and the favorite infection sites are flowers, young fruits and mature fruits. The reason is that some secretions on the floral organ will stimulate the bacteria to multiply rapidly, and once there is a wound on the young epidermis or mature fruit, the bacteria will "follow" the juice from these parts. It was found that Botrytis cinerea had the highest probability of invading fruit from residual petals, accounting for 86.27% ~ 91.61% of all invasions. After dipping flowers with regulators in production, the petal residual rate was 67.71% / 100%. This is also one of the reasons for the high incidence of Botrytis cinerea in greenhouse.

Second, under what circumstances are you susceptible to gray mold?

1. Botrytis cinerea is easy to break out with high humidity.

Weather is an important factor affecting the occurrence rate of Botrytis cinerea. Botrytis cinerea prefers cooler temperatures (18-23 ℃) and high humidity (more than 85%), as well as weather with insufficient light. Therefore, gray mold is easy to break out when it snows or rains on cloudy days.

2. the pathogenicity of bacteria is strong.

The pathogenicity of rapid expansion of Botrytis cinerea is super. Once it invades into plant organs, it will quickly show symptoms and quickly produce new conidia. Therefore, once the disease occurs, it means that the number of pathogens is easy to explode, and the outbreak will occur if there is any delay.

How to prevent and cure Botrytis cinerea?

1. Prevention of gray mold is more important than cure.

Due to the above reasons, it is often too late to give medicine and control after the occurrence of gray mold. Therefore, Botrytis cinerea focuses on prevention.

2. reduce the number of bacteria caused by Botrytis cinerea

Botrytis cinerea lives in the soil and in the residual tissue of plants, so the number of Botrytis cinerea can be greatly reduced before or at the early stage of planting of vegetables or fruit trees, and before and after flowering, especially after dipping in flowers, paying attention to cleaning up these diseased branches, leaves, flowers and fruits, and then comprehensively treating the soil, flower utensils, young fruits and the whole greenhouse with fungicides such as chlorpromazil, carbendazim, and so on.

3. Early use of drugs for control

When Botrytis cinerea infects plants, it first comes into contact with plants. Near stomata, lenticels or wounds, conidia germinate into bud tubes and appressorium, which secrete lysolytic enzymes such as horny protease and lipase through the stratum corneum, destroying the epidermis and forming an infection explosive point on the surface of the plant. Secrete cell wall degrading enzymes such as endogenous polygalacturonase, pectin methyl esterase, cellulase and hemicellulase, which decompose plant organs to help hyphae absorb nutrients.