Detailed Guide to Lychee Pruning Techniques: How to Prune and Control Winter Shoot Growth

Lychee Cultivation Techniques: What does the basic framework pruning of a lychee tree look like, and how should it be pruned for better results? Would you like to find out? Then let us take a look together!

Basic Framework Pruning

The framework of a lychee tree consists of the trunk, main branches, sub-main branches and lateral branches. At 50 cm above the ground on the trunk, begin to train 3~4 main branches, with the main branches forming an angle of about 80 degrees to the horizontal. On each main branch, train 2~3 sub-main branches; the sub-main branches should be attached at an angle of about 10~20 degrees to the horizontal, and the distance between sub-main branches should preferably be about 50 cm. Sub-main branches on different main branches should not cross each other, and sub-main branches on the same main branch should not be retained in the same direction. On each sub-main branch, train 3 lateral branches.

Pruning (Final)

Labor costs can account for 60~70% of the cultivation cost of lychee, so controlling and dwarfing the tree shape to facilitate spraying and harvesting is absolutely necessary. At present, through the efforts of agricultural research institutions and farmers, two models have been developed for dwarfing lychee,

which are briefly described as follows:

The first method involves close planting, with row and plant spacing of 3~4 m. Each year after harvest, 90% of the previous year's growth is cut away (the previous year's fruiting branches retain only 2~3 buds at the base), or mechanical heavy pruning is carried out to keep the plant below 2 m. The applicable varieties are Yu He Bao and Hei Ye of the central region, and the applicable areas are flat land and shallow slopes. This method uses heavy pruning and generous fertilization to cultivate late shoots before the arrival of winter, usually cultivating 3 successive flushes of shoots before flower bud differentiation in order to take advantage of the habit that lychee late shoots often have a relatively high fruiting capacity. This method can be said to push the essence of labor saving to the extreme. However, this method must control shoots at the right time and to the right degree; otherwise, if the winter climate is unstable, such as a warm winter, or a cold early winter followed by a warm late winter, or a rainy winter, the late shoots often cannot obtain sufficiently low temperatures for flower bud differentiation, which in turn leads to unstable yields.

The other method is manual pruning, with row and plant spacing of 6~7 m. The method is to cut off vertically upward-growing branches from the base (thinning) at the time of harvest, and cut back the remaining branches by 1 to 2 flushes of shoots to control the canopy width, keeping the tree shape as an umbrella form below 3 m in height. When canopies come into contact with each other, alternate-tree heavy pruning is adopted to maintain orchard yield. The ideal of this method is to expand the fruiting surface of the tree body as much as possible under the premise of saving labor, so as to increase the yield per tree. The purpose of using wide row spacing is to maintain sufficient light on all sides of the tree to enrich the tree's stored nutrients. This model can be applied to all varieties, but Yu He Bao often needs to be combined with flower thinning treatment or partial flower thinning treatment (that is, the upper part of the tree body where flower thinning is not easy is not thinned); otherwise, excessive flower panicles waste the tree's nutrients and affect fruiting. Therefore, it is necessary to strengthen and improve fertilizer management techniques to eliminate the procedure of flower thinning; otherwise, as the cultivation area of Yu He Bao expands, profits will decline, and flower thinning may not be cost-effective.

In addition to tree shape control, local pruning of branches is also quite important. Its management method varies by variety. Yu He Bao will only fruit if it has thick, strong fruiting branches, so every branch must be carefully managed; the method is to thin out weak branches after the second and/or third flush of shoots, and in principle retain only 1 branch each time branches are removed so that all three flushes continue as single branches. As for non-aborted-seed varieties such as Nuo Mi, Hei Ye, Gui Wei and Huai Li, as long as the branches are not too slender and weak, they can all fruit; it is only a matter of how much they fruit. Therefore, as long as the total yield is not affected, there is no need to care too much about how much fruit each flower panicle sets. Thus the pruning method is to remove inner branches and branches that are denser, disordered or overlapping, and to carry out thinning pruning on lateral branches or fruiting mother branches so that light can penetrate, without the need to carefully manage every branch, thereby reducing costs.

Controlling Winter Shoots

No matter which pruning method is adopted, it is advisable to carry out operations to control winter shoots; especially when the close-planting method is used, shoot control is even more necessary. At present, there are two commonly used methods of shoot control. The first method is to carry out girdling (or ring notching) on the main branches or sub-main branches. The time for girdling is from late October to early November, but for orchards in the central region, early November is preferable; the girdling width varies by variety, about 0.2 cm for Hei Ye, and about 0.3~0.5 cm for Yu He Bao, Nuo Mi and Gui Wei. Note that one main branch or sub-main branch should be left un-girdled to avoid weakening the tree vigor. The second method is for trees that have not been girdled, or that have been girdled but still sprout shoots in winter: when the shoots are still young and tender, spray the leaf surface with Ethrel (39.5%) diluted 1200~2000 times to remove the new shoots; in addition, before flower buds begin to sprout in winter, spray the leaf surface with monopotassium phosphate diluted 500 to 1000 times, once every 10 days, for 2~3 sprays in total.

Whether shoots sprout in winter is greatly related to irrigation and fertilizer management operations. In principle, for varieties other than Yu He Bao, nitrogen fertilizer should no longer be applied after August. In winter, avoid unnecessary irrigation and keep the soil moderately dry to facilitate flower bud differentiation.

Rational Fertilization and the Use of Leaf Analysis

So-called rational fertilization is the technique of taking into account the plant's growth habits and varietal characteristics and applying leaf nutrient diagnosis technology to recommend fertilization, so that the quality and quantity of fertilization conform to the greatest economic benefit. Rational fertilization can not only increase yield and improve fruit quality, but also reduce production costs and enhance the competitiveness of the fruit.

Now you know! You just need to take good care of your trees!