What types of common poplar diseases occur in spring?
Poplar canker mainly occurs during the process of seedling transplanting. The disease begins in late March, peaks from mid-April to late May, basically stops in early June, and slightly develops after October. This disease can infect the trunk, root collar and large branches, but mainly damages the middle and lower parts of the trunk. In the early stage of the disease, near the lenticels on the trunk...
Poplar canker
It mainly occurs during the process of seedling transplanting. The disease begins in late March, peaks from mid-April to late May, basically stops in early June, and slightly develops after October. This disease can infect the trunk, root collar and large branches, but mainly damages the middle and lower parts of the trunk. In the early stage of the disease, blisters appear near the lenticels on the trunk. After the blisters rupture, a foul-smelling liquid flows out, containing a large amount of pathogens. The diseased part eventually shrinks and sinks into canker spots. The cortex at the spots turns brown and rots. When the spots expand laterally and encircle the trunk completely, the tree dies. The disease is prone to occur when poplar growth is weakened. Control methods: 1. Select strong seedlings for afforestation, avoid damaging roots as much as possible when lifting seedlings, and maintain moisture during transport and temporary planting. 2. Before planting, dip the roots in ABT No. 3 rooting powder solution, water thoroughly at planting, and after planting spray the trunk of young trees with 5406 cytokinin 1000-fold solution. 3. In spring, apply whitewash to the lower part of the trunk, or use 0.5 degree Baume lime-sulfur mixture, or spray the trunk with 1:1:160 Bordeaux mixture, which can prevent trunk infection and reduce the disease incidence. If the disease incidence is above 50%, trunk painting will not have an obvious effect, and the trees can be cut back to the ground.
Poplar black spot disease
This disease begins in early May, is most severe in summer and autumn, and lasts until leaf fall. It can damage poplar leaves, petioles, fruit clusters and tender shoots, forming angular, nearly circular or irregular dark brown lesions on them, about 1 mm in diameter, some reaching 5 mm. When there are many lesions, they can merge into irregular large patches and cause early leaf fall. Control methods: 1. Breed and select disease-resistant poplar varieties. 2. During the disease period, spray nurseries and young forests with 200-fold Bordeaux mixture or 85% zineb 250-fold solution. 3. Plant at a reasonable density and thin in time to maintain ventilation and light transmission in the forest. Promptly sweep up fallen leaves in the forest to reduce sources of infection. 4. In early June, spray 40% carbendazim 800-fold solution, or 25% chlorothalonil 600 to 800-fold solution, or a mixture of 0.3% urea and potassium dihydrogen phosphate for control.
Poplar leaf blight
This disease starts from the emergence of poplar leaves and damages poplar leaves, tender shoots and young stems. Infected leaves are most severely affected from May to June. Nearly circular, polygonal or irregular lesions appear on infected leaves, 1 to 5 mm in diameter, and when numerous they can merge into large patches. Dark brown mold-like growth appears on the lesions. The lesions on tender shoots and young stems are sunken, prismatic, and covered with a green mold layer. Control methods: 1. From the onset of the disease, carry out chemical control, spraying 2 to 3 times during the entire growing season, using 40% phosethyl-Al 300-fold solution, or 75% chlorothalonil 500-fold solution, or 50% carbendazim 1000-fold solution. 2. Promptly remove dead branches and fallen leaves and take them out of the forest to burn in a centralized manner or compost them to reduce sources of infection.
Poplar rot disease
It mainly damages various parts of poplar trunks and branches, with irregularly shaped lesions of varying sizes. In the early stage, the lesions are dark brown and water-soaked, then lose water, shrink and sink, and sometimes crack into thread-like forms. Later, many small black dots densely form on the lesions. When moist, curled orange thread-like structures can grow out of the small black dots on the lesions. The lesions of this disease expand outward every year. When they encircle the trunk completely, all upper branches and trunk will die. In years with heavy spring and summer precipitation, rot disease is severe. Control methods: 1. Use a knife to scrape off the lesions, scraping down to healthy tissue, then apply 10-fold edible alkaline water or 20% agricultural antibiotic 120 water agent 10-fold solution to the lesions, applying 2 to 3 times consecutively. 2. In spring or autumn, apply whitewash to the lower part of the trunk, with the mixing ratio of quicklime, salt and water being 1:0.3:10.