How to control Botrytis cinerea? What are the specific drugs?

Gray mold is a common and difficult to control fungal disease of crops in open field and protected land. It belongs to low temperature and high humidity disease. The growth temperature of pathogenic bacteria is 20~30℃, the temperature is 20~25℃, and the humidity lasts for more than 90%. It is caused by Botrytis cinerea infection. Flowers, fruits, leaves and stems can all be infected. Let's take a look at what special drugs are used to control gray mold.

of pyrimethanil

Pyrimethanil is a new fungicide, belonging to aniline pyrimidine. Its mechanism of action is unique. It can prevent the infection of bacteria and kill bacteria by inhibiting the production of pathogen infection enzyme. Its mechanism of action is unique. It is effective against Botrytis cinerea, which has developed resistance to commonly used non-aniline pyrimidine fungicides (benzimidazole and carbamate).

of procymidone

Pythium mainly inhibits the synthesis of triglycerides in the bacteria, has dual functions of protection and treatment, good internal absorption, good low temperature and high humidity conditions.

of carbendazim

A fungicide that has side cross-resistance to carbendazim. The agent enters the cell and binds to tubulin in the cell, thereby affecting cell division. The mode of action is similar to carbendazim, but the two are not at the same point of action. For example, once Botrytis cinerea produces resistance to carbendazim, it is sensitive to ethimefon. On the contrary, the Botrytis cinerea sensitive to carbendazim and ethofencarb showed no antibacterial activity.

ethocarb

After entering the bacterial cell, the ethofencarb agent binds to the tubulin in the bacterial cell, thus affecting the cell division. It has cross resistance with carbendazim, negative cross resistance with carbendazim, and also carbendazim resistance. Botrytis cinerea will be very sensitive to ethofencarb and is generally not used as a single agent.

of iprodione

Iprodione belongs to broad-spectrum contact fungicide, which can inhibit spore germination and mycelium growth of fungi by acting on spores, mycelium and sclerotia simultaneously. It is almost impermeable to plants and belongs to protective fungicides. It has good bactericidal effect on Botrytis cinerea, Sclerotinia, Alternaria, Sclerotinia and Rhizoctonia.

dimethachlon

Sclerotinia sclerotiorum is a powerful fungicide exclusively developed by experts for "fungi, bacteria and viruses" that are easily infected by crops. It has the characteristics of broad spectrum, sterilization, internal absorption, penetration, treatment and long duration of effect. It has dual effects of internal absorption and conduction. Foliar spraying can quickly transmit to the disease site, thoroughly sterilize from the surface and inside, and eliminate a variety of germs at one time.

of fludioxonil

Fludioxonil inhibits the transfer of glucose phosphorylation and inhibits the growth of fungal mycelia, resulting in death of the pathogen. The mechanism of action is unique, and there is no cross resistance with existing fungicides.

polyoxin

Polyantibiotics are metabolites produced by Streptomyces aureus, belonging to broad-spectrum antibiotics. They have good systemic absorption, interfere with the biosynthesis of cell wall of bacteria, and inhibit sporulation and plaque expansion of bacteria.

Integrated Control of Botrytis cinerea

Botrytis cinerea is one of the common diseases in flower production. It often occurs in the growing season of flowers. Light diseases affect leaves, serious diseases can cause a large number of flowers and leaves, affect flowering, cause great harm to the quality and yield of flowers, and seriously restrict the economic benefits of flower production.

Pathogens and hazards

Botrytis cinerea is the pathogen of Botrytis cinerea, and the gray powder in the diseased part is the conidium and conidium of the pathogen. The fungus overwinters in the form of mycelium or conidia and sclerotia attached to the diseased body or left in the soil.

A large number of conidia produced by infected parts were the main pathogens of reinfection. Warm and humid conditions were the main conditions for the epidemic of gray mold. Mature conidia were spread by air flow, rain, irrigation water, shed dripping and agricultural practices. The pathogen was mainly infected through plant wounds, but also directly from flowering organs, necrotic tissues and epidermis. Gray mold is most likely to occur under conditions of relative humidity of about 90% and temperature of 18℃ to 25℃. When the air humidity is large, the disease develops rapidly; the flowerpot is placed too densely, and the greenhouse with poor ventilation occurs seriously; too much nitrogen fertilizer, the plant tissue is tender and weak, and the disease is serious.

Gray mold harm a variety of herbs, woody flowers, such as cyclamen, begonia, begonia, new guinea balsam, melon, fuchsia, phalaenopsis, purse-flowered flowers, poinsettia, primrose, aster, dahlia, dahlia, pelargonium, Stagelina, gladiolus and other more than 50 kinds of flowers.

Gray mold mainly damages leaves, but also branches, petioles, sepals, petals, fruits and seeds. At the beginning of the disease, nearly round purple-brown spots appeared on the leaves, 1 to 5 mm in diameter, and then expanded into irregular large spots, 7 to 12 mm in diameter, with pale brown center and purple-brown edge. There were obvious concentric rings on the spots. The disease spots spread into pieces, and the whole leaves were scorched when it was serious. When the leaf margin is diseased, the leaves are somewhat distorted. Green stems are purple-brown oblong dots, some protrusions, and slow expansion of disease spots. The symptoms on the petiole are similar to those on the stem, but are long strips with dark green mold.

integrated control

To prevent and control flower gray mold, we should take the following measures.

For example, carnation, safflower is more resistant to disease than yellow flower, and safflower is less susceptible to disease than yellow flower under the same conditions.

Note that the seeds are soaked in 10% trisodium phosphate solution for 20 minutes and rinsed with running water for 40 minutes before use. It can also be soaked in 52℃ water for 30 minutes, dried and reserved.

Pathogens mainly overwinter in the soil, so whether it is garden or potted, the soil must be disease-free new soil, and the pot soil, flowerpot, seed ball disinfection.

In order to reduce the source of infection, should be removed at any time, such as diseased flowers, diseased leaves, etc., for withered flowers should also be promptly cut off.

For seed balls and seedlings, the diseased plants should be removed before planting, soaked in 0.3% to 0.5% copper sulfate solution for 30 minutes, washed and dried before planting.

(i) Strengthening field management

Apply sufficient base fertilizer from time to time to promote plant development and enhance resistance. Try to apply decomposed organic fertilizer, increase phosphorus and potassium fertilizer, pay attention to controlling nitrogen fertilizer dosage, prevent excessive growth and improve disease resistance. Early disease in time to remove the disease site, not directly piled in the greenhouse or on the garbage heap, should focus on high temperature heap or deep burial. Strengthen the cultivation management of potted flowers, pay attention to ventilation and light transmission, and leave sufficient space between flowerpots. Watering should follow the principle of "see dry and see wet", basin soil should not be too wet to prevent ponding. Field should pay attention to ventilation and light transmission between plants, timely drainage after rain. In the process of management, plant damage should be minimized to prevent invasion of germs.

(ii) Improvement of environmental conditions

Indoor illumination improves host disease resistance. Watering and fertilization should not be too much, prevent spray watering, watering is best injected from the edge of the flowerpot, so as not to promote the disease due to high leaf humidity. Avoid watering in rainy days. At the end of watering, release air and remove moisture. After the disease control watering, if necessary, take the rhizome around the watering. Different flowers should not be mixed in the same greenhouse. Reduce humidity to reduce canopy and leaf condensation, greenhouse humidity to 80% below, especially in the sunny days after the overcast, this work should be carried out in a timely manner. Pay attention to operation hygiene to prevent disease transmission during management. The suitable temperature for gray mold onset was between 20℃ and 25℃, and the pathogen stopped infection, growth and cultivation above 32℃. Using this characteristic, protected cultivation can control the development and infection of pathogens by increasing temperature. This measure is effective in autumn. Generally, late ventilation in the morning is adopted, but it needs to be maintained at 20℃ to 25℃ in the afternoon. When it is lowered to 20℃, the vent must be closed to keep the temperature between 15℃ and 17℃ at night. If this method is mastered well, it can prevent gray mold without using drugs.

(3) Timely chemical control

At present, there is no specific drug, prevention should be given priority to, seize the right time for chemical control. Can foliar spray, can also fumigate, spray dust.

Before and at the beginning of the disease, spray with 1∶200 Bordeaux mixture once every two weeks.

After the disease, the diseased leaves should be cut off in time and sprayed with chemicals for prevention and control. Generally, protective fungicides are used, such as 50% procyclidine 1000 to 2000 times solution, 50% carbendazim 1000 times solution, 50% carbendazim 500 to 800 times solution, 65% zinc wettable powder 500 to 800 solution, etc., usually sprayed once every 7 to 10 days. Spray should be careful and thoughtful, the best time to apply medicine after 9 a.m., and avoid high temperature and rainy weather medication. Multiple agents should be used alternately to prevent drug resistance.

Chemical fumigation. The formed smoke tablets or powder smoke agents are ignited, and the effective components of the agents are dispersed into small particles by heating method, which can quickly fill the whole planting area and evenly reach the surfaces of all objects, so that some places difficult to reach by spraying liquid medicine can also be coated, and the effect of killing germs is good.

Available formulations include 10% Sukeling (200 - 250 g/667 m2) and 20% Baizuxing (250 g/667 m2). Smoke for three to four hours and let out. It can be carried out on rainy days or after watering, preferably after closing the tuyere in the evening. It works well when the air humidity is high and it is not suitable for spraying liquid medicine.

Dust spray. It can be used in dense plots and enclosed sheds where there is no wind. Mainly use powder sprayer to disperse small particles, strong floating power of the agent in the air, so that it slowly settles and spreads from top to bottom, in order to achieve sterilization effect.

The effective agents include 10% Miekke composite powder, 5% chlorothalonil composite powder, 6.5% Wanmeiling dust, 10% mimerex dust, 5% mimerex dust, sprayed once every 9 to 10 days, continuously or alternately with other methods for 2 to 3 times. The application rate is 1 kg/mu. To aim at the top of the plant spray, spray to close the shed to prevent dust drift by the influence of airflow. Application is best done in the evening or during peak periods on rainy days.

Symptoms and Control of Botrytis cinerea

Botrytis cinerea is one of the most common diseases in flower production. It often occurs during the growing season of flowers, especially in winter and spring. Pathogens can infect any part of the plant ground. If the cultivation management is relaxed, it is more conducive to the occurrence and epidemic of the disease. In serious cases, it can cause a large number of flowers and leaves, affect the flowering of plants, reduce the ornamental value, cause great harm to the quality and yield of flowers, and seriously restrict the economic benefits of flower production.

1. Types of harmful flowers

Gray mold harm a variety of herbs, woody flowers, such as Rieger begonia, New Guinea balsamina, cyclamen, melon, Phalaenopsis, poinsettia, primrose, aster, begonia, dahlia, fuchsia, purple-flowered, dahlia, geranium, gladiolus, Stagelina and other 50 kinds of flowers.

II. Harm symptoms

The disease damages leaves, flowers, pedicels, petioles and tender stems, as well as fruits. Make leaf, flower rot, tender stem breaks, reduce or lose the commodity value of flowers. Gray mold infects leaves, often appearing dark green water-stained spots (such as boiling water burns) at leaf edges or leaf tips, and constantly expanding into leaves, causing brown rot when humidity is high, and gray mold growing on them. When humidity decreases, the affected parts become brown, light brown, withered yellow and other dry shapes (depending on the flower type), brown, light brown, white and other water-stained patches appear on the petals (depending on the flower type), and then rot. Brown patches appear on tender stems or stems with high water content. If the temperature and humidity are appropriate, the disease spots will spread quickly, causing brown rot in the diseased parts, breaking or lodging of branches and stems, wilting and dying of parts above the diseased parts, and death of the whole plant when the disease is serious. No matter what part of the flower disease, in high humidity conditions, the disease grows gray mold is their common feature, but also an important symptom of the disease.

III. Pathogenic bacteria and pathogenesis

The pathogen is Botrytis cinerea, a semi-fungus belonging to Botrytis cinerea, and the gray powder appearing in the diseased part is the conidium and conidium of the pathogen. Conidia slender, erect, branched, 1.3 mm long, terminal cells expanded as spherical, with many peduncles on which conidia are borne, conidia aggregate into grape spikes, conidia ovoid or elliptic, a few spherical, colorless to pale. The fungus overwinters in the form of mycelium or conidia and sclerotia attached to the diseased body or left in the soil. The optimum temperature for the growth of this bacterium is 10-32℃, the minimum temperature is 4℃, and the relative humidity should be maintained at 90%.

A large number of conidia produced by the diseased part in wet condition were the main pathogens of reinfection. Warm and humid conditions were the main conditions for the epidemic of gray mold. The pathogen overwintered on the diseased bodies in the soil, and the mature conidia were transmitted by air flow, rain, irrigation water, shed dripping and agricultural practices. The pathogen has strong pathogenicity to flower organs and leaves, mainly through plant wound infection, but also through direct infection from flowering organs, necrotic tissues and epidermis, and healthy plants are not easily infected. Gray mold is most likely to occur when the relative humidity is maintained at about 90% and the temperature is about 18-25℃. When the air humidity is high, the disease develops rapidly, when the air is dry, the disease develops slowly, the gray mold is less, the flowerpot is placed too densely, and the greenhouse with poor ventilation occurs seriously. If nitrogen fertilizer is too much, the plant tissue is tender and weak, and the disease is serious. Continuous rain, insufficient light, excessive nitrogen fertilizer, poor soil drainage, continuous cropping for many years are easy to be infected by bacteria, the disease is serious. Gray mold is easy to break out when the weather turns sunny and humidity increases after continuous overcast and low temperature. The old leaves of some flowers are sensitive to gray mold, and the decaying leaves and flowers are often the places where gray mold propagates in large quantities. A large number of spores fly into the air and cause disease when they meet suitable temperature and humidity conditions. Spray watering in greenhouses also helps spread germs. Cutting seedlings, because of the use of thin film for arch shed, its humidity is very large, if too much condensed water on the shed film will also aggravate the occurrence of disease. Plants are susceptible to disease in poorly ventilated, shady and humid environments. Generally, in winter and spring in the north, the greenhouse temperature is not high enough and the humidity is large.

IV. Technical measures for prevention and control

Control techniques include variety selection, cultivation techniques, disease prevention and drug protection.

1. variety selection

Selection of resistant varieties for cultivation is the most economical means to control gray mold of flowers. For example, carnation safflower varieties are more resistant than yellow flower varieties. Under the same conditions, safflower varieties are less susceptible than yellow flower varieties.

2. pre-processing

(1) Seed disinfection is to kill fungi attached to the surface of flower seeds. Seeds can be soaked in 10% sodium phosphate solution for 20 minutes and washed with running water for 40 minutes before use. It can also be soaked in warm water at 52℃ for 30 minutes and dried for later use.

(2) Substrate disinfection bacteria mainly winter in the soil, therefore, whether garden or potted, all require the soil is disease-free new soil, and the flowerpot, seed ball disinfection.

(3) To reduce the source of infection is to reduce the source of infection, remove the residues of diseased flowers and leaves at any time, and cut off the withered flowers in time.

(4) For other treatments planted with seed balls and seedlings, remove diseased plants before planting, soak in 0.3-0.5% copper sulfate for 0.5 hours, wash and dry before planting.

3. field management

When planting, apply enough base fertilizer to promote plant development and enhance resistance. Try to apply decomposed organic fertilizer, increase phosphorus and potassium fertilizer, and pay attention to controlling the amount of nitrogen fertilizer to prevent excessive growth and aggravate diseases, so as to keep plants healthy and improve disease resistance. Early disease in time to remove the disease part, not directly piled in the greenhouse or on the garbage heap, should be concentrated for high temperature composting or deep burial. Strengthen the cultivation management of potted flowers, pay attention to ventilation and light transmission, and leave sufficient space between flowerpots. Watering to "see dry see wet", basin soil should not be too wet to prevent ponding. Field should pay attention to ventilation and light transmission between plants, timely drainage after rain. In the process of management, plant damage should be minimized to avoid wounds and prevent germs from invading.

4. Improve environmental conditions and control disease occurrence. Increase indoor illumination, improve host disease resistance. Greenhouse should pay attention to ventilation and light transmission, reduce humidity, avoid placing potted flowers too densely, watering and fertilizing should not be too much, prevent spraying watering, watering is best injected from the edge of flowerpot, so as to avoid high leaf humidity and conducive to disease. Avoid rainy days watering, watering should be ventilated at the end of moisture, after the disease control watering, if necessary, the implementation of the rhizome around the watering. Different flowers should not be mixed in the same greenhouse. Reduce humidity to reduce roof and leaf condensation, greenhouse ventilation in time, humidity to 80% below, especially in the sunny days after the overcast, this work should be done in time. Pay attention to operation hygiene to prevent disease transmission during management.

The optimum temperature for gray mold disease is between 20-25℃, and the pathogen stops infection, growth and reproduction above 32℃. Using this principle, the development and infection of the pathogen can be controlled by increasing the temperature in protected cultivation. The effect is obvious in autumn. Generally, late ventilation in the morning is adopted to increase the temperature in the greenhouse and the greenhouse to 31-33℃, and ventilation is started when it exceeds 33℃. If it is still above 25℃ near noon, ventilation can be continued, but the temperature in the afternoon needs to be maintained at 20-25℃. When it drops to 20℃, the tuyere must be closed, and the temperature at night must be maintained at 15-17℃. If the method is mastered well, it can play the role of preventing gray mold without using drugs. 5. At present, there is no specific drug for chemical control of this disease, so prevention should be given priority to, and chemical control should be carried out at the right time. Can foliar spray, can also fumigate, apply dust.

(1) Before and at the beginning of the disease, spray with 1:200 Bordeaux mixture once every two weeks.

(2) After the disease, cut off the diseased leaves in time and spray chemicals for prevention and control.

(3) Chemical fumigation.

(4) Spray dust.