What are the methods for preventing and treating leaf blight? A detailed explanation
Leaf blight, also known as blight spot disease, is commonly seen in plants and can occur from July to October. The main affected parts are the leaf margins and leaf tips, with more severe disease on the lower leaves of the plant. High temperature and high humidity, as well as poor ventilation, all favor the occurrence of the disease, and plants with weak growth vigor are more severely affected. Let's take a look below at the methods for preventing and treating leaf blight!
Damage symptoms
Leaf blight mostly infects from the leaf margins and leaf tips. The lesions grow from small to large in an irregular shape, ranging from reddish-brown to grayish-brown. The lesions merge into large blighted spots, with the dried area reaching 1/3 to 1/2 of the leaf. The edge of the lesion has a band darker than the lesion itself, and the boundary between diseased and healthy tissue is distinct. Its outer edge sometimes also has a light yellow band of varying width. Subsequently, the lesions gradually extend toward the leaf base until the entire leaf turns brown to grayish-brown. Finally, black fuzzy material or small black dots appear on the back or front of the diseased leaves.
Disease occurrence pattern
The pathogen of leaf blight overwinters on diseased leaves. The following year, when the temperature is suitable, the spores of the pathogen are spread by wind and rain to host plants and cause infection. It can occur from July to October, with more severe disease on the lower leaves of the plant. High temperature and high humidity, as well as poor ventilation, all favor the occurrence of the disease, and plants with weak growth vigor are more severely affected.
Prevention and treatment methods
1. In autumn, thoroughly remove diseased fallen leaves and burn them in a centralized manner to reduce the source of infection the following year.
2. The planting site should have good drainage and fertile soil, and more organic fertilizer as well as phosphorus and potassium fertilizers should be applied.
3. Control the planting density so that the plants receive ventilation and light, reducing leaf surface humidity and lowering the chance of infection.
4. Change spray watering to drip irrigation or running water irrigation to reduce the spread of the pathogen.
5. During the growing season, in severely affected areas, from the early stage of disease onset in late June to October, spray once about every 10 days. Several consecutive sprays can effectively prevent and control it. Commonly used agents include 1:1:100 Bordeaux mixture, 50% thiophanate 500-800 times solution, 50% carbendazim wettable powder 1000 times (or 40% suspension concentrate 600-800 times), 50% benomyl 1000-1500 times, 65% zineb 500 times solution, etc., which can be selected for use or used alternately.