Master These Techniques and Pre-Winter Orchard Management Won't Be a Struggle Anymore
Most fruit trees enter dormancy in winter. At this time, deciduous fruit trees have basically shed their leaves and shoot growth has stopped, but a series of activities still continue inside the tree body, such as respiration, transpiration, bud differentiation and development, and root absorption. The Start of Winter is coming soon, and many growers have left comments saying they don't know how to manage the orchard before winter to ensure that next year's yield won't decrease and the trees won't be damaged. Master these techniques, and pre-winter orchard management will no longer be a struggle.
1. Protect the leaves
Once a fruit tree flowers and sets fruit, whether it can produce high-quality fruit and achieve high yields is closely related to the protection of its leaves that year.
The nutrients accumulated by the fruit tree in the previous year are basically used up after flowering, leaf growth and new shoot development, from late May to early June, and the tree enters the nutrient transition period.
The so-called nutrient transition period is the shift from using nutrients stored from the previous year to using nutrients produced in the current year. The current year's nutrients come from leaf photosynthesis, so only by protecting the leaves well can the normal development of the current year's fruit be guaranteed.
After the Start of Autumn, the leaf synthesis function of fruit trees reaches its peak. The earlier the base fertilizer is applied, the more inorganic nutrients can be converted into organic nutrients through photosynthesis, supplying fruit enlargement and flower bud differentiation.
The reason the alternate bearing phenomenon occurs is that in an on-year the fruit tree consumes too much while fertilizer input is insufficient, making it difficult for flower buds to form, so there is no yield the following year.
From this it can be seen that in autumn fruit tree management, protecting the leaves and applying base fertilizer early is the guarantee of a bumper harvest in the current year and the foundation for a bumper harvest the next year.
2. Water appropriately
An appropriate water supply is an indispensable condition for maintaining the tree's life and obtaining yield and benefits.
The so-called appropriate amount means adapting to the physiological development habits of the fruit tree: water when it should be watered, and control water when it should be controlled.
Because most apple-producing areas have insufficient water conservancy conditions, it is relatively difficult to water at the right time. Therefore, once the opportunity to water is seized, fruit growers are accustomed to flood irrigation, hoping to water thoroughly in one go. This practice is wrong. Excessive watering during the growing season is one of the main causes of vigorous shoot growth.
The principle that solving lighting conditions is conducive to high and stable yields has been valued by fruit growers for many years. One of the important purposes of reshaping is to solve the lighting problem.
In understanding lighting, there is an important “80/20 rule”, namely that the input of fertilizer and water accounts for only 20% of the contribution rate to fruit trees, while 80% of the contribution comes from photosynthesis. Not solving the lighting problem is equivalent to wasting natural resources that cost nothing.
3. Fertilize appropriately
Insufficient investment is one of the important reasons currently restricting the improvement of orchard benefits. The prominent manifestation of insufficient investment is the severe shortage of fertilizer input.
After mineral nutrients in the soil are absorbed by fruit trees, a large part is transformed and stored in the fruit, which is equivalent to taking mineral nutrient elements out of the soil.
Therefore, the nutrient return theory holds that whatever is taken from the soil should be replenished, and however much is taken should be replenished. In this sense, if fertilizer is not applied in sufficient amounts, the soil will become increasingly barren and the productive capacity of the fruit trees will become increasingly lower. Countless facts prove that any orchard with consecutive years of high and stable yields invariably attaches importance to fertilizer input.
Most fruit growers “fertilize according to the fruit”, that is, investing more fertilizer in an on-year and less or even no fertilizer in an off-year, leaving the fruit trees “starving one meal and stuffing the next”, which often results in tree weakness and serious damage from various diseases. Through rational fertilization and rational load, gradually adjusting to eliminate the alternate bearing phenomenon is currently the main task of fruit tree management.
In fertilization, particular attention should be paid to autumn fertilization. The total amount of autumn fertilization should account for two-thirds of the annual fertilization amount. When necessary, in addition to soil fertilization, supplementary methods such as trunk painting and foliar spraying should also be used.
4. Water and fertilizer are the foundation, spraying is the guarantee, pruning is the coordination
Water and fertilizer are essential elements for supplying the tree's growth and development. At no time should the tree be allowed to run short of fertilizer or water.
In fertilization, first ensure that the amount of autumn base fertilizer is sufficient, and then supplement during the growing season according to the tree vigor and fruiting situation.
Generally speaking, the root system enters its peak activity period before germination and during the spring shoot cessation period, and fertilizer should be supplemented to the roots at these times, but large-scale root cutting is not advocated; surface broadcasting or flushing application should be the main method, and at other times foliar spraying and other extra-root fertilizer supplementation should be the main method. As for watering, except for winter irrigation, which can water the whole orchard, watering between rows is preferable in other seasons.
The purpose of spraying is to prevent and control pests and diseases. In addition to choosing the right pesticide, the timing of spraying, the dosage and the spraying method are crucial. Generally speaking, diseases should be prevented in advance, with pesticide applied before onset, while for pests, pesticide should be applied after a certain population density is reached. Adding insecticide every time regardless of whether there are pests often causes waste.
For pest and disease control, the water volume must be sufficient and atomization must be good. Only in this way can the leaves be fully and evenly covered with pesticide. When spraying, focus on the underside of the leaves, because the stomata on the leaf underside are dense and can absorb the pesticide solution well.
The cuticle layer on the upper leaf surface is not conducive to pesticide absorption. Many people spray until the upper leaf surface is dripping wet while the leaf underside is still dry; this kind of spraying has the worst effect.
The main purpose of pruning is to regulate lighting and regulate nutrient distribution. In fruit tree pruning, attention should be paid to pruning in all four seasons. Practice has proved that the “two regulations and one control” technical system promoted by the Yuncheng Green Association is a very good regulation measure for the growing season.
Orchards that conscientiously implement this technical system have lighter winter pruning tasks. The mistaken practice of focusing only on winter pruning and not on four-season pruning must be corrected.
Taking an apple orchard as an example:
1. Spring pruning: includes branch bending to open angles, bud notching and pre-bloom supplementary pruning. Pre-bloom supplementary pruning is carried out after flower bud morphology can be accurately identified. Its main task is to regulate the flower quantity so that the ratio of flower buds to leaf buds reaches a suitable level, and attention should also be paid to removing diseased and pest-infested branches, dead branches and overlapping branches missed during winter pruning.
2. Complete topdressing, watering, loosening soil and preserving moisture. Apply quick-acting fertilizer as early as possible after the soil thaws and before germination, which can be applied in strip trenches or ring-shaped trenches. The fertilizer amount based on urea is: 20-30 kg per mu for young trees, 40-60 kg per mu for early fruiting trees, and 100-150 kg per mu for full-bearing trees. Water promptly after fertilization to preserve moisture, and cover the tree dish for young trees after fertilization.
3. Check and scrape to treat rot disease, branch ring rot and dry rot. For scars already scraped, apply pesticide again after an interval of 1 month. In mid to late March, spray the whole tree with 3-5 degrees Baumé lime sulfur mixture or 500-fold dilution of Junduqing and other pesticides to kill overwintering dormant individuals of various pests and diseases such as red spiders, scale insects, rot disease and powdery mildew on the tree surface.