Detailed Explanation of Key Points for Autumn Cultivation Techniques of Longan
I. Restoring tree vigor and enhancing stress resistance. After several months of fruiting, longan trees have consumed a large amount of nutrients. The 4-month management period in autumn from August to November is a critical time for a bumper longan harvest the following year. Pre-harvest and post-harvest fertilizers should be applied promptly to promote longan fruit enlargement, increase longan yield and...
I. Restoring tree vigor and enhancing stress resistance. After several months of fruiting, longan trees have consumed a large amount of nutrients. The 4-month management period in autumn from August to November is a critical time for a bumper longan harvest the following year. Pre-harvest and post-harvest fertilizers should be applied promptly to promote longan fruit enlargement, increase longan yield and quality, and at the same time restore longan tree vigor early, enhance stress resistance, and lay the foundation for high and stable longan yields next year. Taking each tree producing 100 jin of longan fruit as an example for the specific fertilizer amount, the pre-harvest fertilizer should be mainly quick-acting fertilizer applied 15 days before harvest, with 2 kg of imported compound fertilizer per tree, applied after rain or during irrigation; the post-harvest fertilizer should be 2 kg of ternary compound fertilizer and 100 kg of human manure and urine per tree. For the fertilization method, dig a trench vertically below the edge of the canopy, 20-30 cm deep, cover with soil after application; where conditions permit, combine with one irrigation of the orchard to increase soil moisture, improve the fertilizer uptake effect of longan trees, and accelerate the recovery of longan tree vigor.
II. Cultivating fruiting mother branches to lay the foundation for a bumper and high yield the following year. The most ideal fruiting mother branch of longan is the last matured autumn shoot, so after fruit harvesting, water and fertilizer management of the mother tree should be strengthened promptly to promote the sprouting of autumn shoots and cultivate the autumn shoots into strong fruiting mother branches. Use water and fertilizer to control the uniformity of autumn shoot sprouting, which also facilitates orchard management and pest and disease control.
III. Pruning and training. To give longan trees a good canopy and increase longan yield per unit area, shaping and pruning of longan trees should be carried out twice a year. Spring pruning should be combined with flower and fruit thinning, and autumn pruning should be combined with post-harvest pruning of the tree shape and canopy after fruit picking, cutting back overly vigorous branches (referring to young bearing trees), and pruning off weak branches inside the canopy, branch stubs just after fruit harvest, diseased and insect-damaged branches, and crossing branches, to improve ventilation and light penetration inside the canopy, restore longan tree vigor, naturally regulate the balance of endogenous hormones in the tree, and ensure the flower formation rate of longan the following year.
IV. Pest and disease control. Autumn temperatures are suitable, so attention should be paid to pests such as the longan psyllid, fruit borer, and Acrocercops sp. For pest control methods, during the peak hatching period of larvae after forecasting, or at the early stage of new shoot sprouting, organize fruit growers to carry out comprehensive chemical control spraying. In conjunction with the control of other pests, use (1) 20% Fenpropathrin 2000 times or 10% Baimieke 2000 times solution for spraying; (2) 2.5% Decis 2000 times solution for spraying, once every 15 days until the new shoots mature. For witches' broom disease, deep pruning of diseased branches should be adopted, and at the same time water and fertilizer management should be strengthened to cultivate thick and strong buds and shoots.
V. Transforming low-yield orchards. As autumn temperatures decline, longan root activity increases. At this time, low-yield orchards and neglected orchards should undergo hole protection and soil improvement, increased application of organic fertilizers, improvement of orchard soil structure, enhancement of soil aeration, water retention, and fertilizer retention capacity, and increase of soil fertility. In addition to applying sufficient nitrogen, phosphorus, and potassium fertilizers, other trace element fertilizers needed for longan growth should also be applied. Trace elements should mainly be applied by foliar spraying to ensure the needs of longan growth and development at each stage. At the same time, the soil should be loosened, longan fibrous roots renewed, root activity improved, longan tree vigor rejuvenated, and strong fruiting mother branches cultivated, laying a good foundation for fruiting the following year.