According to investigations conducted by the Daifu Township Center of Xiangyang City and tea farmers, brown leaf spot disease occurred in tea plants, especially the brown leaf spot of Anji white leaf tea. Because the brown leaf spot disease is very similar to the frost damage, most people mistaken the disease for frost damage without control.
The disease can be distinguished from freezing injury in the following ways. One is that there is a gray mold layer on the lesions in the wet condition, and there is no mold layer on the frozen lesions; the other is that the lesions are not like the frozen lesions; the upper leaves of the tea tree are mostly, and the whole plant leaves have lesions; the third is the frozen lesions in the same block. The differences between the tea plants on the ground are not significant, and the differences between the strains of the lesions can be large, and the tea trees, which are closely adjacent to the diseased plants, have no symptoms for the time being.
Brown leaf spot symptoms. Brown leaf spot disease is a typical low-temperature and high-humidity disease. It occurs only in late autumn and early spring, and it is in a stagnant state in winter. The symptoms are further aggravated in early spring when the temperature rises. The lesions seen at other times are old lesions. At the early stage of disease, brown spots were formed from the tip of the leaf margin, and then gradually expanded into irregularly shaped purple-brown or dark brown lesions. The purple-black part of the lesion was wider, and the boundary of diseased and healthy parts was not particularly obvious. The overwintering buds of brown leaf spot tea tree have a weak germination potential, affecting the production of spring tea, and the leaves of the tea tree are concentrated in advance before pruning (the life span of tea tree leaves is about one year. If you do not prune, you can see that normal large amount of leaf fall time should be in June) . It has also been found that small green leafhoppers and crickets are more serious than brown leaf spot disease.
Prevention methods. There are many agents for controlling brown leaf spot of tea plants, such as myramide, difenoconazole, dimoxystrobin, manganese zinc preparations, copper preparations, and trichoderma. In mid-November, different agents were applied alternately at the beginning of the disease and were sprayed every other week. Early spring application should pay attention to when the tea, pay attention to safety intervals.
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