Harmful symptoms and control methods of strawberry powdery mildew

Strawberry powdery mildew is a major disease in strawberry production. Strawberry powdery mildew can occur in the whole growing season of strawberries. Infection at the seedling stage results in a decline in the quality of seedlings, which is not easy to survive after transplanting. The quality of strawberries is seriously affected and the yield, quality and economic benefits of strawberries are seriously affected. Let's take a look at how to treat strawberry powdery mildew.

Symptoms of strawberry powdery mildew

Strawberry powdery mildew mainly harms leaves, petioles, flowers, pedicels and fruits, but rarely occurs on stolons. In the early stage of the disease, a thin white mycelium layer grew on the back of the leaf. With the aggravation of the disease, the leaf curled upward in the shape of a spoon and produced dark stains of different sizes. After that, the disease spot gradually expanded and a layer of thin frost-like white powder was produced on the back of the leaf. In severe cases, multiple disease spots were connected to the whole leaf. The buds and flowers are infected, the petals are pink, and the buds cannot open. When the fruit is infected, the young fruit can not expand normally and dry up.

The cause of strawberry powdery mildew

The main results are as follows: 1. Strawberry powdery mildew is a disease of low temperature and high humidity, the optimum temperature is 1525 ℃, the optimum temperature for conidia occurrence and infection is about 20 ℃, and the relative humidity is above 90%. If we encounter less sunshine such as continuous overcast, rain, fog and snow from late autumn to early spring, low temperature and high relative humidity are conducive to the continuous production of spores and repeated infection, resulting in the outbreak of the disease.

2. The incidence of strawberry in continuous cropping in greenhouse was early and serious, and the onset period of the disease was about 1 month earlier than that in the newly built greenhouse. The onset of the former is mostly in mid-October, while the latter does not appear until mid-November. Fertilization is closely related to the disease, partial application of nitrogen fertilizer, strawberry growth is exuberant, the leaf surface is large and tender green easy to suffer from powdery mildew. If the appropriate period, appropriate amount of nitrogen fertilizer, increase the application of phosphorus and potassium fertilizer, the disease will be lighter.

How to treat strawberry powdery mildew?

1. Use protective fungicides to prevent the disease twice before flowering, spray with 200 times of 2% Wuyisin water or 600 times of 75% chlorothalonil wettable powder once every 7 to 14 days, and the effect of alternate use of agents is better.

2. After the onset of the disease, drugs with protective and therapeutic effects should be selected for prevention and treatment. 3000 times of 50% ether carbendazim water dispersible granule or 1000 times of 4% tetraflurane water agent should be sprayed once every 7 to 10 days, and the effect of alternate use is better.

Prevention of strawberry powdery mildew

1. Select disease-resistant varieties and cultivate disease-free and strong seedlings.

2. Reasonable crop rotation to reduce the occurrence of diseases.

3. Remove old leaves, diseased leaves and residual leaves in time, and do a good job in field health management.

4. reasonable irrigation, control the humidity in the shed and reduce the disease.

5. Reasonably control the amount of nitrogen fertilizer and apply more phosphorus and potassium fertilizer.

How to do strawberry powdery mildew in greenhouse? Control of Strawberry powdery mildew in greenhouse

Powdery mildew is the main disease of strawberries in greenhouse, which occurs in the whole growing period of strawberries. Especially after the budding and flowering of strawberry entered the fruiting period, the damage was the most serious, which seriously affected the growth and development, yield and quality of strawberry. What about strawberry powdery mildew in the greenhouse? Next, let's introduce the prevention and control of strawberry powdery mildew in greenhouse.

The prevention and control of strawberry powdery mildew in greenhouse should be based on prevention and comprehensive control, so as to achieve the combination of agricultural control and chemical control, so as to improve the yield and quality.

Agricultural Control of Strawberry powdery mildew in greenhouse

1. Reasonable rotation. Reasonable rotation should be carried out where there are conditions, so as to reduce the number of bacteria and reduce the occurrence of diseases.

2. Select disease-resistant varieties and disease-free seedlings.

3. Pick the diseased leaves of the old leaves in time, and take the diseased leaves out of the field to destroy them so as to reduce the probability of re-infection.

4. Rational fertilization to prevent partial application of nitrogen fertilizer.

5. rational irrigation, control the humidity in the shed and reduce the occurrence of diseases.

Chemical control of strawberry powdery mildew in greenhouse

The key to chemical prevention and control is to give priority to prevention, and two points should be mastered:

First, timely prevention and treatment, spraying twice before flowering, spraying immediately at the initial stage of the disease after flowering, and continuous medication for 2-3 times in seriously diseased fields.

The second is medicament selection, which should consider the characteristics of strawberry growth. Due to the high economic value of strawberry and the relatively closed environment of strawberry growth in greenhouse, safety should be considered first, especially in flowering and fruiting period. Nitrilazole, Shigao control effect is good, safe for strawberry production, can be used in a large area, the use of 12.5% nitrilazole and 10% of the world as high as 1500 times is better, production should not blindly increase the concentration, especially nitrilazole, high concentration will have an adverse effect on strawberry growth. The prevention and control of strawberry powdery mildew in greenhouse should be based on prevention, and the same pesticide should not be used alone for a long time, but should be used alternately to improve the control effect and prevent the disease from producing drug resistance.

Control methods of strawberry powdery mildew

In the process of strawberry growth, powdery mildew is one of the main diseases harmful to strawberry growth, so how do we control strawberry powdery mildew?

Strawberry powdery mildew mainly affects leaves and tender tips, and flowers, fruits, fruit stalks and petioles can also be damaged.

Control methods of strawberry powdery mildew:

(1) selecting disease-resistant varieties.

(2) clear the strawberry plants and all kinds of weeds in the shed or field before planting, clean the orchard in winter and spring, burn the rotten stems and leaves, remove the diseased leaves in time and burn them in the growing season.

(3) reasonable close planting, strengthen soil fertilizer and water management, enhance plant growth, improve their own disease resistance, fruit growers try not to "cross the shed" with each other to avoid man-made transmission.

(4) prevent partial application of nitrogen fertilizer, control overgrowth, pay attention to ventilation, and prevent excessive wetness in time after rain.

(5) when diseased vines and diseased fruits are found, they should be gently picked as soon as possible before the morning dew has dissipated, burned or buried deeply in a convenient bag.

(6) Chemical control: grasp the timely chemical control in the early stage of the disease. Sulfur fumigation technology to prevent disease: the reason why Japan is not resistant to powdery mildew strawberry varieties Fengxiang, Niufeng, Zhang Ji, Gunugan and other areas are still very large, mainly using sulfur fumigation technology to restrain the harm of powdery mildew. The sulfur fumigation technology is to install a fumigator per 100m2 in the greenhouse. The fumigator contains 20g of 99% sulfur powder and begins to be heated and fumigated after covering the curtain in the greenhouse in the evening. Every other day, each time for 4 hours, pay attention to observation and supplement when the sulfur powder is insufficient. The fumigator hangs 1.5 meters from the ground in the middle of the greenhouse. In order to prevent sulfur gas from hardening the greenhouse film, an umbrella-shaped waste film can be set up 1 meter above the fumigator to protect the greenhouse film. This method is harmless to bees, but the fumigator temperature should not exceed 280℃ to avoid sulfite damage to strawberries. If the temperature in the greenhouse exceeds 20 ℃ at night, the dosage should be reduced. 50% Baifenjing suspension 600x liquid; available 70% methyl topiramate 1000 times liquid; 25% fumigant wettable powder 3000-5000 times liquid; 50% bacillus 800 times solution, 30% Teflon 5000 times liquid; 10% Shigao water dispersible granules 2000-2500 times liquid spray control; 40% Fuxing 10000 times solution; 12.5% nitrilazole EC 1500 times solution; bactericidal fumigant chlorothalonil, smoked Ling, can be mixed fumigation Once every 7-10 days, a variety of drugs can be used alternately to prevent resistance.