Control Methods for Anthracnose in Mango Cultivation
1. Damage symptoms: It mainly damages mango flowers, fruits and young shoots. After young leaves are infected, many round brown spots appear, surrounded by yellow halos, and gradually expand into round, polygonal or irregular brown lesions, which later rupture and perforate. The wounds on leaves and young fruits caused by gall midges, leafhoppers and other pests are also easily infected by this disease. Severely infected young leaves tend to curl, and the leaf tips and margins often become scorched and withered, and diseased leaves fall off easily. After branches are infected, black spots form and they gradually dry up. After flower clusters are infected, small spots appear and finally turn black and rot, causing flower rot and fruit drop. Fruits can be infected throughout the entire growth period. After young fruits are infected, they become deformed, turn black and drop off. After larger fruits are damaged, dark brown round spots form on the peel, the center sinks, and the diseased part becomes hard and deteriorated. When the weather is humid, pink sticky matter grows on the diseased part. In addition to damaging mango during the growth period, this disease continues to cause damage during fruit storage and transportation, resulting in a large number of rotten fruits.
2. Pathogen and occurrence pattern: Anthracnose is a disease caused by fungal infection. After the pathogen overwinters in diseased parts, it is spread by humans, livestock, rainwater, wind and insects, and invades through stomata or wounds on plants or fruits. High humidity is the leading factor inducing anthracnose. When relative humidity reaches above 95% and is maintained for 12 hours, the pathogen invades, and the incubation period is 2-4 days; it can occur throughout the year. In all parts of Hainan Province, especially in northeastern Qiong, from November each year to April of the following year, the disease can occur when relative humidity is above 95% and temperature is 12-30°C; especially under weather conditions with a temperature of 16-25°C and relative humidity of 95%-100%, anthracnose is most likely to break out and cause disaster, resulting in poor harvests and crop failure. The anthracnose pathogen has the characteristic of latent infection, mostly lurking in the peel and flesh near the fruit stalk, or in the leaf mesophyll near the petiole, at a depth of about 1mm.
3. Control measures
3.1 Clean the orchard: In late autumn and early winter, cut off diseased branches and leaves and burn them in a centralized manner, and spray the whole orchard once with 1:2:100 or 1:1:100 Bordeaux mixture.
3.2 Training and pruning: After harvesting fruits in summer, prune and train the plants in a timely manner to improve light penetration and ventilation conditions.
3.3 Pesticide control: During the flowering period, spray once a week, using 600-fold chlorothalonil solution, 50% carbendazim 500-fold solution, 70% thiophanate-methyl 800-fold solution, 40% miebingwei 400-fold solution, 25% prochloraz emulsifiable concentrate 1000-fold solution (bud stage), and 20% chlorocupric emulsion 600-fold solution (on rainy days). At the same time, spray the leaves once every 7-10 days with 0.2%-0.3% potassium dihydrogen phosphate, urea and borax; spraying flower and fruit retention agents 2-3 times continuously can effectively enhance the disease resistance of the plants. During the fruiting period, spray once every half month, and the following pesticides can be used in rotation: 70% thiophanate-methyl 700-fold solution, 1:1:100 Bordeaux mixture, 75% chlorothalonil 600-fold solution, 25% prochloraz emulsifiable concentrate 800-fold solution, and 20% chlorocupric oil 500-fold solution. After harvest, soak the fruits in 70% thiophanate-methyl 1000-fold solution (water temperature 52-54°C) for 15 minutes, take them out and dry them in a ventilated place, pack them in cardboard boxes or bamboo baskets, or move them to a low-temperature controlled-atmosphere warehouse for storage; alternatively, 15 days before harvest, spray with 25% prochloraz 700-800-fold solution and soak the fruits for 15 minutes, then pack them. During the autumn shoot growth period, spray once every half month, and the pesticides used are basically the same as those used during the flower and fruit periods.