Control techniques of diseases and insect pests of Shatian pomelo

Shatian pomelo was first planted in Shatian Village, Rong County, Guangxi. it was exported to Hong Kong, Nanyang, Europe and America as early as the 1930s, and has a strong competitiveness in the international market. now it has been expanded to Xunjiang, Longjiang, Guijiang, Lijiang and Hongshui River basins in Guangxi. Guangdong, Hunan, Sichuan, Zhejiang and Jiangxi have also been introduced. Let's take a look at Shatian pomelo pest control techniques.

Scab disease

[harm] scab mainly harms spring shoots and young fruits. The leaves show oil-immersed spots at the beginning of damage, then turn waxy yellow, the disease spots expand, and protrude to one side into conical tumor grains, like horn or funnel, and the surface is rough. If the disease spot is focused, the leaves will twist and become deformed, the fruit will also become deformed fruit, and the fallen leaves and fruits will fall seriously. When the weather is wet, there is a layer of gray mildew at the top of the spot, which is spread by wind, rain and insects. From April to May, the disease is easy to occur when the daytime temperature is 15-24 ℃, and it is easy to occur in closed orchards, especially in case of continuous overcast and rain.

[prevention and control] disease-free seedlings should be selected in the new garden of ①. Scions and seedlings from non-disease-free nurseries and outside can be soaked with 50% benzoate 800 times or 50% carbendazim wettable powder 800-1000 times for 30 minutes. In winter, ② should cut off insect branches, weak branches and shade branches and burn them centrally, so as to make the canopy well ventilated and transparent, reduce humidity, and spray 0.5 Baumedushi sulfur mixture once. ③ strengthens daily management and applies more potash fertilizer to make the extracted shoots neatly and rapidly mature. ④ can choose 75% chlorothalonil wettable powder 600% 800 times liquid or 0.5% equivalent Bordeaux solution or 70% methyl thiophanate wettable powder 1000 times solution to protect new shoots, leaves and young fruits during spring bud germination and flower completion.

Brown rot Phytophthora

[harm] Brown rot Phytophthora mainly harms the fruit and causes a large number of fruit drop after infection. In the early stage of the disease, a light brown dot appeared on the pericarp, which expanded rapidly and showed dark brown waterlogging, and the spot became soft and slightly sunken. In the environment of high temperature and high humidity, sparse pure white hyphae can be produced on the surface of the fruit, and the diseased fruit gives off a stinky smell. It occurred in the whole fruit growth and development period of Shatian pomelo, but the disease was more serious from May to August.

[prevention and control] strengthen the management of ①, timely remove the diseased fruit and disinfect the orchard with quicklime powder, pay attention to ditching to reduce stagnant water and prevent waterlogging, and properly prune to improve the ventilation and light transmission of the orchard. During the growth and development of ② fruit, nitrogen, phosphorus and potassium combined with farm manure were applied to make the tree strong and enhance its resistance. According to the characteristics of short incubation period and fast onset rate of the disease, ③ should spray the crown and the ground at the same time after wind and rain in the high temperature and rainy season. It can be sprayed with 53% Jinreidi water dispersible granule 600 times 700 times, 90% bengshuangling wettable powder 700 times or 72% grams of plague cream 800 times, and then spray once every 7 days.

Black spot disease

[harm] the pathogen infects the young fruit after flowering, but does not show symptoms immediately, and the black star or black spot appears only when the fruit is nearly ripe. Black star fruit initially scattered reddish brown spots, and then expanded into a round, showing a "crater" shape, does not invade the pulp. The black-spotted fruit suffers from primary yellowish or yellowish-brown spots, and then gradually expands into dark brown or dark brown round or irregular spots connected to each other. The disease is easy to occur in the warm and humid climate in spring and summer, especially in the grapefruit orchards with weak tree potential, dense canopy, low-lying stagnant water and poor ventilation and light permeability. the peak of the disease is from September to November when the fruit is ripe.

[prevention and treatment] ① can be protected by spraying 500x solution of 50% methyl thiophanate wettable powder, 600x liquid of 77% methyloxane wettable powder or 300x 400x solution of 45% crystal stone sulfur mixture 15 days after flowering, once every 7 days for 2 times in a row. ② winter and spring garden cleaning combined with pruning to remove diseased branches and leaves, fallen leaves, fallen fruit and concentrated burning. ③ increased the application of organic fertilizer, reasonable mix of nitrogen, phosphorus and potassium, to promote tree vigor and improve disease resistance.

Rusty spider

[harm] Adult nymph mites gather in leaves, fruits and twigs to absorb juice, and the damaged fruits and leaves are bronzed with rough surface and no luster. In serious cases, the leaves curl, yellow and fall off, and the fruit surface turns black, which affects the growth and development of pomelo and the yield and quality of pomelo fruit. There are more than 35 generations of rust spiders in Guilin, and the generations overlap, so that the adult nymph overwinters on the branches and leaves, and there is no obvious overwintering period. It began to feed on harmful spring shoots from March to April, and spread to fruit from May to June, and then the number of insect population increased sharply, reached the peak from July to August, and reached its peak from July to October.

[control] when the density of rust wall lice reaches an average of 2 × 3 per field of vision (10 times of hand-held magnifying glass), or when a few black fruits and rusty brown leaves are found in individual trees, pesticide control should be paid attention to protect natural enemies such as black lady beetles and lacewings. 1.8% avermectin EC 2000 × 3000 times or 73% gram partridge EC 2000 times. The orchard with a large amount of insects was sprayed once again after half a month, and the medicine was used continuously for 2 or 3 times. attention should be paid to the inside of the crown, the back of the leaves and the dark side of the fruit when spraying.