Peach fungal leaf perforation disease is caused by C1zsterospari_eum czrpophilam (Lereill) Aderhold of the subphylum Deuteromycota. It mainly damages the leaves of peach trees. If not treated in time, it will cause the leaves to perforate and fall off, the new shoots to die, and the fruits to become diseased, thus seriously weakening the tree vigor and reducing the yield and quality of the fruit.
Occurrence pattern
The pathogenic bacteria overwinter in diseased fallen leaves and other places. The spores of the pathogen spread to the leaves with airflow and invade directly or through wounds. Symptoms will appear after 5 to 6 days.
Characteristics and identification methods
The conidia of the pathogenic bacteria are oval, olive-colored, 4 to 6 cells, and formed on short stalks. Its size is 23 to 62 microns × 12 to 18 microns, with thin septa and transparent terminal cells. Injured leaves produce circular or irregular lesions with circular patterns on the edges and purple outer edges; light green lesions with purple edges may also occur, and the lesions will fall off after drying and form perforations.
Use pesticides
(1)Mancozeb
Dosage form: 70% wettable powder.
Control period: Spray from after the peach tree leaves unfold to the early stage of the disease.
Usage method: Use 18 grams of 70% mancozeb wettable powder, mix with 15 kilograms of water, dilute it into an 800-fold solution, stir and spray evenly.
Precautions:
① This agent can be mixed with a variety of pesticides, but cannot be mixed with alkaline or copper-containing drugs.
②The temperature during storage should not exceed 30°C. Pay attention to moisture-proof and store in a cool and dry place. Unused medicine should be tightly sealed.
③After spraying the pesticide, the fruits of the fruit trees can be eaten after being rinsed with clean water. There will be no acute poisoning problem.
(2)Thiophanate-methyl
Dosage form: 70% wettable powder.
Control period: Spray once immediately when you see sporadic lesions on the leaves, then apply once every 15 days or so, and apply 2 to 3 times continuously.
Usage method: Dilute 15 grams of 70% thiophanate methyl wettable powder with 15 kilograms of water to a 1000-fold solution, stir and spray evenly.
Precautions:
① Continuous application of this agent may cause pathogenic bacteria to easily develop drug resistance. Rotation or mixed application with other agents should be considered, but it should not be used in rotation with carbendazim, benomyl, etc.
② It can be mixed with a variety of insecticides and fungicides, but cannot be mixed with inorganic copper preparations such as Bordeaux mixture.
③Keep in a closed, dry and cool place.
(3)Carbendazim
Dosage form: 50% wettable powder.
Usage method: Use 30 grams of 50% carbendazim wettable powder, add 15 kilograms of water, dilute it to a 500-fold solution, stir and spray evenly.
Precautions:
① Multiple consecutive single applications of this agent may easily cause pathogenic bacteria to develop drug resistance. Therefore, it should be used alternately or mixed with other drugs, but it cannot be mixed and rotated with drugs that are prone to cross-resistance such as thiophanate, benlide, and thiabendazole.
② This agent cannot be mixed with strongly alkaline agents and copper-containing agents.
③ This medicine should be protected from sunlight when stored.
(4)Chlorothalonil
Dosage form: 75% wettable powder.
Usage method: Use 18 grams of 75% chlorothalonil wettable powder, mix with 15 kilograms of water, dilute to 800 times solution, stir and spray evenly.
Precautions:
① This agent has an irritating effect on human skin and eyes. A few people have allergic reactions, which generally cause mild contact dermatitis.
② This agent is poisonous to fish. When applying the agent, it must be kept away from ponds, lakes and streams. The liquid used to clean the agent must not pollute the water source.
