What are the control methods for powdery mildew on Japanese euonymus?
Symptoms:
The disease damages leaves and twigs. The lesions are mostly distributed on the upper surface of the leaves. In the early stage of the disease, many small white round spots are scattered on the infected leaves. As the lesions gradually expand and merge with each other, they become irregular large spots. When the disease is severe, the infection rate of new shoots can reach 10%. White powder appears on the entire surface of the leaves and new shoots. The diseased leaves gradually lose their green color, turn yellow, and finally turn brownish black. The diseased parts become deformed, the diseased leaves shrink, and the diseased shoots become twisted and stunted.
Disease pattern:
The pathogen overwinters as mycelium inside the diseased plant tissues. In the spring of the following year, the pathogen produces a large number of conidia, which are spread by airflow and cause infection. The conidia can be produced repeatedly and cause re-infection. The pathogen parasitizes the surface of the host branches and leaves and produces haustoria that penetrate deep into the epidermal cells to absorb nutrients. High summer temperatures are not conducive to the development of the disease. Plants planted under tree shade are severely affected, while adjacent plants facing the sun are less affected or not affected. Young leaves and new shoots are severely affected, while old leaves are only mildly affected.
Control:
② Chemical control: In the early stage of the disease, spray 25% triadimefon wettable powder at 1500-2000 times dilution, or 70% thiophanate wettable powder at 800-1000 times dilution, or 0.3-0.5 degree Baume lime sulfur mixture, or 50% tuijunte wettable powder at 800 times dilution, once every 10-15 days, spraying 2-3 times.
Control methods for powdery mildew on Japanese euonymus
During the growth process of Japanese euonymus, it is very easily harmed by powdery mildew, which affects its growth. Powdery mildew on Japanese euonymus is widely distributed. When harmed by it, a white powdery mold layer grows on the leaves and new shoots, reducing its ornamental value. Below, the editor shares with you the control methods for powdery mildew on Japanese euonymus.
Disease pattern of powdery mildew on Japanese euonymus
The pathogen overwinters as mycelium in the damaged tissues of Japanese euonymus and as a gray membranous fungal layer. In the following spring, during leaf expansion and the growth period of Japanese euonymus, a large number of conidia are produced and spread through airflow to cause infection, becoming the inoculum source for the primary infection of the disease. The pathogen parasitizes the surface of the host branches and leaves, produces haustoria that penetrate deep into the epidermal cells to absorb nutrients, and produces a large number of spores in spring, summer, and autumn each year to infect the leaves and new shoots many times. High summer temperatures are not conducive to the development of the disease, while rainy seasons and high humidity conditions favor its occurrence, and cool and rainy autumn weather favors the disease. Japanese euonymus planted under tree shade is severely affected; young leaves and new shoots are severely affected; and Japanese euonymus with excessively dense branches and leaves is more severely affected.
Control methods for powdery mildew on Japanese euonymus
1. Improve cultivation conditions, and plant in areas that are dry, have sufficient light, do not accumulate water, and have deep, fertile soil.
2. Strengthen fertilizer and water management, apply more phosphorus and potassium fertilizer and an appropriate amount of nitrogen fertilizer; pay attention to drought resistance and drainage so that the seedlings grow robustly and their disease resistance is improved.
3. In combination with pruning, cut off diseased branches and diseased leaves.
4. Reasonably use chemicals for timely control, and pay attention to alternating chemicals to avoid powdery mildew fungi developing resistance; spray carefully and thoroughly, and be sure to spray the inner canopy and the undersides of leaves. In winter, use 3 degree lime sulfur mixture for control twice, with an interval of 1 month. During the leaf expansion period and growth period of Japanese euonymus, especially from April to May and from September to October, the following chemicals can be selected for control: 25% triadimefon wettable powder at 1500 to 2000 times dilution, or 70% thiophanate-methyl wettable powder at 800 to 1000 times dilution, or 50% benomyl wettable powder at 1000 to 1500 times dilution, or 50% tuijunte wettable powder at 800 to 1000 times dilution, etc. Apply immediately when the disease first appears, spray once every about 7 to 10 days, and spray 4 to 5 times continuously.
The above is the article on control methods for powdery mildew on Japanese euonymus shared with you by the editor. I hope the above can help you.
Control of powdery mildew on Japanese euonymus
Japanese euonymus is a common hedge plant and shaping material in gardens, but because powdery mildew occurs commonly, its ornamental value is reduced, restricting its application in landscaping.
Powdery mildewIt mainly damages the leaves of Japanese euonymus. The lesions are mostly distributed on the leaf surface and produce white powdery mold spots; when the disease is severe, the undersides of leaves and new shoots can also be affected, causing leaves to shrink and become deformed, new shoots to become twisted, stunted, and stop growing, and causing leaf drop and shoot dieback. In the early stage of the disease, many small white round spots are scattered on the leaves. As the lesions gradually expand and merge with each other, they become irregular large spots, even covering the entire leaf surface. If the white powdery layer on the surface of the lesions is wiped off, yellow round spots appear at the diseased sites. The pathogen overwinters as mycelium (that is, a gray membranous fungal layer) in the damaged tissues of Japanese euonymus or between bud scales. In the following spring, during leaf expansion and the growth period of Japanese euonymus, a large number of conidia are produced and spread through airflow to cause infection, becoming the inoculum source for the primary infection of the disease. The pathogen parasitizes the surface of the host branches and leaves, produces haustoria that penetrate deep into the epidermal cells to absorb nutrients, and produces a large number of spores in spring, summer, and autumn each year to infect the leaves and new shoots many times. High summer temperatures are not conducive to the development of the disease. High temperature is the main factor in the occurrence of the disease.
Control measures:
1. Improve cultivation conditions. The planting site should be relatively high, dry, have sufficient light, not accumulate water, and have deep, fertile soil.
2. Strengthen fertilizer and water management, apply more phosphorus and potassium fertilizer and an appropriate amount of nitrogen fertilizer; pay attention to drought resistance and drainage so thatseedlingsgrow robustly and their disease resistance is improved.
3. In combination with pruning, cut off diseased branches and diseased leaves. Do a good job of winter garden cleaning, sweep up diseased branches and leaves and burn them in a centralized manner; during the growth period, promptly cut off and burn diseased leaves and diseased branches when found, which can effectively reduce the sources of primary infection and re-infection inoculum of the disease.
4. Reasonably use chemicals for timely control, and pay attention to alternating chemicals to avoid powdery mildew fungi developing resistance; spray carefully and thoroughly, and be sure to spray the inner canopy and the undersides of leaves. In winter, use 3 degree lime sulfur mixture for control twice, with an interval of one month. During the leaf expansion period and growth period of Japanese euonymus, especially from April to May and from September to October, the following chemicals can be selected for control; 25% triadimefon at 800 to 1000 times dilution, 70% thiophanate-methyl at 800 times dilution, 50% benomyl at 1000 to 1500 times dilution, 50% tuijunte at 800 times dilution, 40% asomate at 600 times dilution, 0.3 to 0.5 degree lime sulfur mixture, or 2% polyoxin aqueous solution at 200 times dilution.