Control Methods for Scab Disease in Mango Cultivation
1. Symptom characteristics
It mainly damages the fruit, and young new shoots and leaves can also be affected. All affected parts show rough, slightly raised scab spots that are lignified. Small dark brown, slightly raised, lignified spots first appear on the fruit surface; later the lesions become densely packed and merge into patches, with a rough surface and a sunken center or star-shaped cracking, and in severe cases the peel cracks. Severely diseased new leaves may become deformed and twisted and tend to fall early. The cortex of affected new shoots becomes rough or cracked or forms dead shoot tips. When humid, grayish-white mold spots appear on the affected parts.
2. Pathogen and disease occurrence characteristics
The pathogen is Sphaceloma mangiferae Bit. et Jen., a fungus of the Deuteromycotina. The fungus overwinters as mycelium and acervuli in diseased plants and diseased residues left in the soil, and conidia are spread by wind and rain for primary and secondary infection. Long-distance spread of the disease occurs mainly through the transport of diseased seedlings. Seeds may also transmit the disease. More disease occurs in warm and rainy years, especially in weather with large day-night temperature differences and high humidity, which favors disease occurrence. Nearly mature fruit is susceptible. Young leaves and shoots of seedlings are more prone to the disease than those of mature fruiting trees.
3. Control methods
(1) Implement quarantine; once diseased seedlings are found during introduction, they should be burned immediately. (2) In combination with pruning, remove diseased branches and leaves and burn them in a centralized manner. (3) Spray pesticides in time to protect shoots and fruit. In nurseries, the main focus is protecting shoots and leaves; in fruiting orchards, the main focus is protecting fruit. During the shoot-flushing stage and from the beginning of fruit enlargement to 15-20 days before harvest, alternately spray 12 Bordeaux mixture, 30% copper oxychloride + 70% thiophanate-methyl (1:1) at 1000 times dilution, 40% sulfur-multi suspension concentrate at 600 times dilution, and 50% mixed sulfur at 600 times dilution 3-5 times.