1. Separate diseased plants from healthy plants in time;

2. Cut off the diseased part and burn the diseased branches and leaves;

3. Drug therapy

(1) Use baking soda: Powdery mildew can't survive in alkaline state, and adding 50kg water to 50g baking soda can effectively prevent powdery mildew.

(2) Using vinegar: wiping the diseased plants with water and spraying the leaves at the ratio of 1: 50 can also effectively alleviate the symptoms.

(3) Using oleander: Mash oleander leaves, soak them in clear water for about a day, filter out the juice and spray them on the diseased plants. If you use oleander continuously for 3-4 days, it can play a therapeutic role, but you should pay attention to the toxicity and protect yourself when using oleander.

Extended data:

Powdery mildew is caused by fungi. The pathogen overwinters on the diseased plant residues, and when the temperature rises in the next spring, the pathogen spreads through airflow or water droplets. When the temperature is between 20℃ and 25℃ and the humidity is high, it invades the host and causes the disease. Therefore, excessive watering and poor ventilation and light transmission will make the disease spread rapidly.

Methods of controlling powdery mildew:

1, select varieties with mild disease or disease resistance.

The resistance of different flower and tree varieties to powdery mildew is significantly different, so it is the most economical and effective method to choose varieties with light disease or strong disease resistance for planting.

2, buy seedlings to choose disease-free plants.

When buying seedlings, the infected plants should be strictly removed to eliminate the source of the disease. When expanding propagation, cuttings or tillers without diseases and insect pests should be cut as asexual propagation materials. When seedlings leave the nursery, they should be treated with pesticides to prevent diseased seedlings from entering new areas.

3. Crop rotation

Rotation with non-host flowers and trees for 2 ~ 3 years to reduce the source of disease.

4. Strengthen cultivation management.

During the wintering period from late autumn to early spring of the following year, thoroughly clean the nursery, cut off branches of pests and diseases, and centrally destroy them; Remove diseased branches and leaves in time during the growth period, thoroughly remove fallen leaves, cut off branches with pests and diseases and branches with too dense middle and lower parts, and destroy them centrally; It is not advisable to plant too densely, and the shed should be ventilated to reduce humidity; Clear the accumulated water in the fields and flowerpots in time, and don't have too much water at the edge of the pots, so as not to drench the stems and leaves, thus reducing the spread and incidence of germs; Apply more phosphorus and potassium fertilizer and less nitrogen fertilizer to make plants grow healthily, and apply more decomposed organic fertilizer to enhance plant disease resistance.

5. Prevent diseases of flowers and trees in greenhouse.

Before raising seedlings in the greenhouse, all plants in the greenhouse should be thoroughly removed, the shed room should be cleaned, and strict disinfection should be carried out by means of drug fumigation. Strictly prevent sick seedlings from entering the house, try to plant a single variety of flowers and trees in the shed to avoid mixed planting and prevent cross-infection. Before the flowers and trees germinate in the open field in early spring, the shed can only be opened after all the diseased plants in the shed are eliminated to prevent the pathogenic spores from spreading outside the shed.

6. Chemical control during the wintering period, spraying branches with dilute solution of sulfur mixture with Baume degree of 3 ~ 5 degrees. Flowers that are easily damaged by drugs, such as Guayeju, cannot be used. Spray sulfur powder on the ground, generally 25 ~ 30 grams per 70 square meters, to eliminate the source of overwintering bacteria. Protective agent can be sprayed before the onset of growth period, and systemic agent should be sprayed after the onset. According to the symptoms, the growth of flowers and trees, the climate and the characteristics of pesticides, the pesticide should be applied once every 5-20 days and continuously for 2-5 times. For flowers and trees in one season, a systemic agent can only be applied 1 ~ 2 times, so it is necessary to change the types of pesticides frequently to prevent bacteria from developing drug resistance.

References:

Baidu encyclopedia-powdery mildew