What are the key technical points for summer management of apple orchards?
Apples can be said to be one of the fruits that people cannot do without in daily life, rich in vitamins and dietary fiber, especially suitable for the elderly and children to eat. Apple cultivation in our country is relatively widespread, and because of differences in climate and other factors across regions, the varieties grown also differ. During apple cultivation, summer orchard management is extremely critical, and in particular the corresponding technical points must be mastered.
1. Do not irrigate with large amounts of water
Summer is the season when fruit trees have the greatest water demand and transpiration, so water must be replenished in time, but flood irrigation is not advisable. This is because flood irrigation easily causes excessive vegetative growth of the tree, resulting in the suffocation and death of a large number of fine absorbing roots. Although the soil water content is high after flood irrigation, excess water in the soil pores causes root hypoxia, death of fine roots, and blocked water transport, which in turn leads to leaf transpiration and water shortage, causing leaf scorch or wilting. Therefore, when to irrigate the orchard, how to irrigate, and how much to irrigate should depend on the weather, the soil, the fruit load, and the tree vigor. If the tree vigor is stable, the fruit load is large, and the weather is dry with no rain and poor soil moisture, irrigation will neither cause excessive shoot growth nor fail to plump the fruit, and can also promote flower bud formation. Seepage irrigation, furrow irrigation, hole irrigation, drip irrigation, or application with a flushing gun give the best results.
2. Apply topdressing in time
Fertilizer is the tree’s “grain”, and water is the tree’s “soup”. When topdressing and irrigating from June to July, more fertilizer and less water make the tree vigorous and likely to form flower buds; more water and less fertilizer make the new shoots falsely vigorous and difficult to form flower buds.
Most fruit growers believe that for fruit to grow large, water is king and fertilizer is grain. When applying fruit-swelling fertilizer, they often choose high-nitrogen, high-potassium compound fertilizer and carry out flood irrigation, resulting in the fruit tree being unable to stop growth in time, fewer flower buds differentiating, severe alternate bearing, late fruit maturity, poor color and bland taste, and declining quality. The correct approach is to increase the application of phosphorus and potassium fertilizer, or low-nitrogen, medium-phosphorus, high-potassium fertilizer and trace element fertilizer in summer, to ensure good fruit coloring, large size, and good market appearance.
3. Do not rotary till for weed control
After bagging the fruit, many fruit growers rotary till the ground until it is completely clean, with not a blade of grass in sight, and the soil dry and the air stale. In fact, deep digging of the tree plate during the fruit tree growing period will greatly damage the shallow absorbing roots at 5-20 cm, making these absorbing roots, which are the most active in growth, the most sensitive to temperature and humidity, and the strongest in absorbing nutrients and water and synthesizing cytokinins, unable to fully function, so flower buds are difficult to form, and the fruit has low sugar content and poor color. On the other hand, rotary tilling too deep will damage the surface absorbing roots and is more conducive to the development of deeper growing roots, stimulating autumn shoot growth and forming falsely vigorous trees. At the same time, July is the period of the dog days, and when the temperature is above 30 degrees C, the respiration consumption of roots and leaves will accelerate. The surface temperature of grass-grown orchards is 3-5 degrees C lower than that of clean-cultivated orchards. Many years of production practice show that frequent mechanical rotary tillage during the fruit tree growing period from April to August is truly a futile act of “earnestly making mistakes and steadily causing destruction”.
The principle of underground management during the fruit tree growing period is no-tillage, growing grass, and mulching with grass. Natural grass growing must not be allowed to form a “weed orchard”; when the grass grows too tall, it should be mowed in time and mulched under the tree plate. This is because grass is a self-generating and self-maintaining organic fertilizer and a regulator of temperature and moisture, and if properly regulated, it can turn harm into benefit.
4. Do not prune too many branches
Summer pruning is a powerful measure to promote flower bud formation. Some fruit growers prune the new shoots on the upper side of branches until the ground is covered with them, originally intending to improve the tree’s light conditions, but in fact destroying the root-crown balance relationship, leading to “the upper side branches being shaved bare and sunburned, the exposed young fruit suffering sunscald, the stopped branches and buds growing again, and flower bud differentiation being affected”. If the upper side branches are too dense, keep the vigorous new shoots with “large leaves, short internodes, and fast terminal bud formation”, and properly thin out some water sprouts and falsely vigorous shoots with “tender branches, yellow leaves, and long internodes”. For new shoots that cannot stop growth in time, twist them intermittently to check growth and promote vigor. For new shoots that “burst the bud by rushing to the top”, break off the terminal bud to suppress the top and promote sprouting.