Shaping and pruning techniques of early fruiting walnut

Pruning Techniques of Early Fruiting Walnut

Walnut tree shape should be selected according to soil conditions and planting density, usually scattered stratified shape and natural open center shape, dense planting garden can adopt free spindle shape and slender spindle shape. The tree has 6 ~ 7 main branches, which are arranged in 2 ~ 3 layers. Generally, there are 3 branches in the first layer, 2 branches in the second layer and 1 ~ 2 branches in the third layer. The crown is semicircular or conical, which is suitable for sparse planting with good soil fertility. The shaping and pruning technique for the dispersed hierarchical tree is as follows.

Young trees are pruned. (1) Dry. According to the variety characteristics, soil thickness, fertility, etc. to determine the height of dry. Early fruiting walnut is smaller than late fruiting walnut, trunk can be shorter, fixed stem height 0. 8 ~ 1. 2m, 1 ~ 1. 2m。2. Select the main branch. Early fruiting walnut has many branches, and the selection and retention of the first layer of main branches are completed in 1 ~ 2 years. The three main branches at the base are adjacent to each other, avoiding the phenomenon of "pinching neck" caused by rotation, and the distance between layers is 20 ~ 30cm. After 3 ~ 4 years of planting, the second layer of main branches is selected and reserved, and the layer spacing is 1m. The second layer spacing 0. 8m。The main branches of each layer are staggered up and down, inserted and selected to avoid overlapping. The horizontal angle between the three main branches is about 120°, the base angle of the main branches is 55~ 65°, the waist angle is 70 ~ 80°, and the tip angle is 60 ~ 70°. 3. Select lateral branches. 2 lateral branches are reserved on the first layer of main branches, 1 ~ 2 on the second layer of main branches, and no lateral branches are reserved on the third layer of main branches. The secondary branches of the same order should be selected on the same side of the main branch to avoid mutual interference. The distance between the first lateral branch and the central trunk is 80 ~100cm, and the distance between the second lateral branch and the first lateral branch is 40 ~ 60cm. The lateral branches are best placed on the oblique side of the main branch, and the horizontal angle with the main branch is 45 ~ 50°. Side branches avoid leaving back branches.

Tree pruning at early fruiting stage. Continue to cultivate main branch, lateral branch and fruiting branch group, use auxiliary branch to bear fruit early and expand fruiting position. Control of secondary branches. When one flourishing fruiting branch sprouted more than 3 secondary branches, 1~ 2 stronger ones were selected and toppled in summer; when 1 ~ 2 flourishing secondary branches sprouted, they were cut short in summer and cultured into fruiting branch group. When the secondary branches of vegetative branches are not lignified, those that are overgrown and affect the growth of other branches are thinned out. (2) Use long branches. The latent buds at the base of early fruiting walnut branches are easy to germinate long branches. In the second year, more than 7 fruit branches can be produced. Their growth potential gradually weakens from top to bottom. In the third year, the small fruit branches in the middle and lower parts are mostly dried and fallen off, and bare nodes appear, resulting in the outward movement of fruit parts. Therefore, the method of restraining the front and promoting the rear can be adopted. After germination in spring, the short or pinching can be adopted. For the branches with a diameter of about 3 cm, the horizontal shape can be pulled before and after germination to slow down the growth potential and form fruit branches. (3) thinning out overdense branches. Due to the early fruit walnut branches more, branch quantity is large, easy to cause too dense branches inside the crown so that poor ventilation and light transmission, to timely thinning thin too dense branches. 4. Handle the lower branches of the back well. The lower branches of the main branches sprout early, grow vigorously, and have strong competitiveness, which is easy to cause the original branches to weaken or even die, so they should be cut off early. If the original branch becomes weak or the branch angle is too small, the original branch is cut off or cultured into a fruiting branch group, and the original branch is replaced by the lower branch. If the dorsal branches grow moderately and have formed axillary flower buds, they can retain fruit, retract at appropriate branches after fruiting, and culture into small fruiting branch groups.

Tree pruning at full fruiting stage. The vegetative growth of walnut trees in full fruit stage gradually weakened, the crown opened, the peripheral branches increased, the inner bore ventilation and light transmission were poor, the twigs were easy to dry up, the fruiting area began to decrease, and the phenomenon of big and small fruiting easily appeared. At this time, pruning is aimed at keeping fruit yield and prolonging full fruit period, cutting off dense thin branches, dry branches, overlapping branches, drooping branches and diseased branches, increasing the permeability of crown, improving lighting conditions, and promoting the growth of rich and healthy bearing mother branches and developing branches. Keep as many healthy branches as possible. Thinning away over-dense branches year by year, cutting saw cuts to be flattened.