How to prevent and control pests and diseases of Shatian pomelo? Latest technical method tutorial
Shatian pomelo is named after Shatian Village in Rong County, Guangxi, where it was first planted. As early as the 1930s, it was exported to Hong Kong, China, Nanyang, Europe, and the Americas, and it has strong competitiveness in the international market. It has now been expanded to the Xunjiang, Longjiang, Guijiang, Lijiang, and Hongshui River basins in Guangxi. Guangdong, Hunan, Sichuan, Zhejiang, and Jiangxi have also introduced it successively. Now let us take a look at the pest and disease control techniques for Shatian pomelo!
Scab
[Damage] Scab mainly damages spring shoots and young fruit. When the leaves begin to be affected, oil-soaked spots appear, then turn waxy yellow. The lesions expand and bulge on one side into conical wart-like protrusions, resembling ox horns or funnels, with a rough surface. If the lesions converge, the leaves become twisted and deformed, and the fruit also becomes deformed, with serious leaf and fruit drop. When the weather is humid, a layer of gray mold appears on top of the lesions, spread by wind, rain, and insects. The disease is prone to occur in April to May when the daytime temperature is 15-24°C. Closed orchards are more susceptible, and the disease is even more severe during continuous rainy weather.
[Control] 1. New orchards should use disease-free seedlings. For scions and seedlings from non-disease-free nurseries and external sources, soak them in 50% benlate 800-fold solution or 50% carbendazim wettable powder 800-1000-fold solution for 30 minutes. 2. During winter orchard cleanup, prune out insect-damaged branches, weak branches, and shaded branches and burn them centrally, so that the canopy has good ventilation and light transmission and humidity is reduced, and spray 1 time with 0.5 Baumé lime sulfur mixture. 3. Strengthen daily management and apply more potassium fertilizer so that the new shoots emerge neatly and mature quickly. 4. During the spring bud germination and elongation period and after flowering is complete, you can use 75% chlorothalonil wettable powder 600-800-fold solution, 0.5% equal-amount Bordeaux mixture, or 70% thiophanate-methyl wettable powder 1000-fold solution to spray and protect new shoots, young leaves, and young fruit.
Brown rot Phytophthora disease
[Damage] Brown rot Phytophthora disease mainly damages the fruit, causing massive fruit drop after infection. At the initial stage, small light brown round spots appear on the peel. These small round spots rapidly expand and become dark brown water-soaked areas. The lesion area becomes soft and slightly sunken. Under high temperature and high humidity, sparse pure white mycelium can be produced on the fruit surface, and the diseased fruit gives off an irritating stuffy odor. It occurs throughout the entire fruit growth and development period of Shatian pomelo, but is more severe from May to August.
[Control] 1. Strengthen management, promptly remove diseased fruit, and spread quicklime powder on the orchard floor for disinfection. Pay attention to digging ditches to reduce standing water and prevent waterlogging, and prune appropriately to improve ventilation and light transmission in the orchard. 2. During the fruit growth and development period, apply fertilizer by combining nitrogen, phosphorus, and potassium with farmyard manure to promote strong tree vigor and enhance resistance. 3. In view of the short incubation period and rapid onset of this disease, during hot and rainy seasons, after wind and rain, spray the canopy and the ground at the same time in a timely manner. You can choose 53% Jinglei Duomier water-dispersible granules 600-700-fold solution, 90% Yishuangling wettable powder 700-800-fold solution, or 72% Keyishuang wettable powder 800-fold solution for spraying, and spray again after 7 days.
Black spot
[Damage] The pathogen infects young fruit after flowering, but symptoms do not appear immediately. Only when the fruit is nearly mature do black star-type or black spot-type lesions appear. In the black star type, the affected fruit initially has scattered reddish-brown small spots, which later expand into round shapes with a “crater” appearance, without invading the flesh. In the black spot type, the affected fruit initially develops light yellow or yellow-brown spots, which gradually expand into dark brown or black-brown round or irregular lesions that connect into patches. This disease is prone to occur in warm and humid climates in spring and summer. It is especially obvious in pomelo orchards with weak tree vigor, dense canopies, low-lying water accumulation, and poor ventilation and light transmission. The peak incidence period is when the fruit matures from September to November.
[Control] 1. Starting 15 days after flowering, you can use 50% thiophanate-methyl wettable powder 500-fold solution, 77% Kechade wettable powder 600-800-fold solution, or 45% crystalline lime sulfur mixture 300-400-fold solution for protective spraying, once every 7 days, for 2-3 consecutive times. 2. In winter and spring, during orchard cleanup, combine with pruning to remove diseased branches and leaves, fallen leaves, and fallen fruit and burn them centrally. 3. Apply more organic fertilizer and reasonably match nitrogen, phosphorus, and potassium to promote strong tree vigor and improve disease resistance.