Detailed Explanation of Key Techniques for Autumn Management of Apple Trees

The peak period of flower bud differentiation in apple trees occurs in autumn. Doing a good job of autumn management of apple trees can lay a solid foundation for high, stable and high-quality yields in the following year.

Fertilizer and water management

For non-bearing trees, 0.15-0.25 kg of diammonium phosphate can be applied per tree; for large bearing trees, according to the planned yield for the following year, 0.7 kg of pure nitrogen and 0.7 kg of available phosphorus can be applied per 100 kg of fruit. Topdressing for young trees can significantly increase the sprouting rate in the following year. For large trees in full bearing period, applying fertilizer in autumn year after year, under the same amount and types of fertilizer, compared with topdressing in early summer, can increase the yield by about 50 kg per tree.

In autumn, in conjunction with the prevention and control of apple pests and diseases, spray 0.3%-0.4% urea plus potassium dihydrogen phosphate twice. In mid-October, during the nutrient backflow period, spray 0.3% urea once on the leaves.

In September, apply base fertilizer in autumn (for late-maturing varieties, this can be postponed to early to mid-October). Weeds, leaves, diseased fruit, etc. should be buried deeply together with the base fertilizer, and at the same time apply 5% of the total fertilizer amount as quick-acting nitrogen and phosphorus fertilizer. This has a significant effect on improving soil fertility and promoting apple root growth. According to soil moisture conditions, water appropriately, and never use flood irrigation, so as to avoid causing excessive autumn shoot growth and affecting fruit coloring. In mid-to-late November, water once with frozen water to help the fruit trees overwinter.

Pruning

Autumn pruning can improve ventilation and light transmission conditions in the tree canopy, increase fruit coloring, improve quality, and also has a clear effect on increasing the number of flower buds for the following year. When the canopy is too dense, or when there are too many autumn shoots on the outer upper layer affecting light, thin out or retract some tender shoots, water sprouts and long hanging branches. The long shoots left after thinning can be bent and softened in mid-to-late August to change their growth polarity. When the tree body is too tall and there are too many auxiliary branches between layers, the top can be lowered appropriately and the interlayer branches cleaned up after fruit picking, but the number should not be too large. Bending branches in autumn makes it easier to form flower buds than bending branches in spring, and at the same time can avoid producing a large number of vigorous shoots on the back. For vigorous non-bearing trees, bend the lateral branches, generally at an angle of 70-80 degrees. This branch bending improves light, stops long shoot growth, fills out new shoots, and reduces the workload of winter pruning.

Pest and disease control

The main autumn insect pests of apple trees include peach fruit borer, phalera flavescens, lithocolletis ringoniella, and large green leafhopper, etc.; diseases include ring rot, anthracnose, and valsa canker, etc. Valsa canker is at this time in its second (autumn) peak incidence period of the year, so it should be scraped off in time and treated with medicine. For other pests and diseases, comprehensive control should be carried out according to local insect and disease conditions to improve the rate of good fruit. This also has a clear effect on preventing young trees from shriveling and improving the tree's cold resistance in winter. It should be pointed out that after entering August-September, it is best not to spray Bordeaux mixture, so as not to affect the coloring of red varieties.