Control of main Diseases in shoot and Stem of Tea Plant

In order to effectively control tea plant diseases and insect pests, reduce pesticide residues in tea and improve tea quality, the main tea diseases and their control are introduced as follows.

I. harmful symptoms

1. Tea bud blight: after the tea tree is susceptible, the bud growth is obviously hindered, affecting the yield and quality of spring tea, mainly harming 1 to 3 leaves of spring tea, first produce light yellow or yellowish brown disease spots on the leaf tip or leaf edge, after expansion is irregular, the edge of the disease is obvious or not obvious; the bud tip is damaged in the shape of black-brown scorched, atrophy can not be extended; in the later stage, there are fine black spots on the surface of the diseased part, and the black spots on the leaves are mostly on the front. The susceptible leaves are fragile and twisted.

two。 Tea white spot disease: the disease harms the tender shoots and leaves, resulting in extremely bitter tea taste, forming small round disease spots on the tender leaves, sunken in the center, reddish brown at first, purplish brown at the edge, and fine black grain spots scattered in the later stage. The diameter of the lesion is 0.5mm. When the spot is often connected to each other, it can form a larger spot and distort the leaves.

3. Tea seedling blight: the disease mainly harms the base of tea seedling stem, but also harms new shoots. The disease spot was dark brown in the initial stage, oval or irregular in shape; in the later stage, it was gray-white, the disease spot was slightly sunken, and there were many small black spots on it, and finally the leaves withered and fell off, and the whole plant withered.

4. Stem blight of tea seedlings: the disease often harms short-spike cutting nurseries and can cause death in serious cases. The stem base of the killed tea seedlings near the ground was brown at the beginning, dark brown at the later stage, the cortex rotted, and the seedlings withered after 2-3 months.

II. Pathogen

The pathogen of tea bud blight is a fungus belonging to the subphyla, and the small black spot in the disease part is a conidium, spherical to oblate and brown. The conidia is located in the spore organ, oval or oval, colorless, single spore, with a size of 1.6 μ m × 2.3 μ m. Xanthomonas campestris is a fungus of the genus Alternaria, the small black spot on the spot is a conidium, the conidia is located in it, colorless, monospore, oval, the size is 3 × 5 μ m × 2 μ m.

Third, occurrence regularity

The pathogen of tea bud blight overwintered on diseased leaves or overwintering buds by mycelium or conidia. During the sprouting stage of spring tea in the following year, conidia produced and spread with wind and rain, infected young buds and formed new disease spots after 2-3 days. When the content of amino acids in spring tea was high, the disease was serious. After mid-June, the development of the disease was inhibited, and it could be continuously re-infected during the onset period, resulting in serious losses of spring tea. The varieties with early germination were more susceptible to the disease. Xanthomonas campestris overwintered in the diseased tissue with mycelium or conidia. When the temperature and humidity were suitable in early spring of the following year, conidia spread by wind and rain, infected tender shoots and leaves, and produced new disease spots 2 or 5 days later. Then conidia were produced for re-infection. The environment is suitable and easy to cause the disease epidemic, which occurs most seriously in April and May every year. The wet, foggy weather and poor cultivation and management are conducive to the occurrence of the disease. When the average temperature is higher than 25 ℃, it is disadvantageous to the occurrence of the disease. Tea seedling blight is mainly transmitted by wind and rain, and the disease begins in the first ten days of April. The autumn rain season from August to October is the peak period of the disease. High temperature and humidity conditions are conducive to the occurrence of the disease. The stem blight of tea seedlings often occurs in the rainy season and autumn from April to May. The pathogen spreads with Rain Water or running water, and it can also be transmitted through intertillage weeding or agricultural activities. The pathogen can still maintain the ability of infection in the soil after 1 or 2 years, and the disease is more serious in the extensive nursery.

IV. Prevention and control measures

1. Strengthen cultivation management: strengthen tree culture, increase the application of organic fertilizer and phosphorus and potassium fertilizer, select disease-resistant varieties according to local conditions, and improve the stress resistance of tea trees. Timely picking, frequent picking, strengthening tea garden cleaning to reduce the source of bacterial infection, diseased plants were immediately removed, taken out of the nursery to burn, and quarantine should be strengthened when transporting seedlings. For vertical blight, we should also pay attention to drainage and waterlogging, and stem blight should pay attention to disinfecting soil or seedbed.

two。 Timely application of pesticide control: tea bud blight in tea sprouting period and disease? Tarsal hip reeling? For the second time, 70% methyl topiramate 1500 times solution and 50% carbendazim 1000 times solution can be used to control tea white spot disease during the period from sprouting to fish leaf development. 80% Dysen zinc solution, 50% carbendazim 1000 times solution, 70% methyl thiophanate 1000 times 1500 times solution can be selected, and the tea garden with serious disease should be sprayed again after 7 days and 3 times as appropriate. Tea seedling blight should be sprayed with 1000 times of methyl topiramate, 75% chlorothalonil and 65% zinc at the initial stage of the disease. the stem blight of tea seedlings can be controlled by spraying actinone in April and August. 25 kg of 40% pentachloronitrobenzene powder can also be applied to the rows of tea seedlings, then loosen the soil and water, and then apply it again after 15 days.