When should you water a "wisdom fruit" apple tree? How much to water and how to water it - there's an art to it
When planting apples, if you want a high yield, you need to master watering well, because too much water in an apple tree affects flower formation and makes the tree grow vigorously again, while a lack of water leads to small fruit, fruit that is easily flattened, and poor coloring, so technique is very important. So when is the best time to water an apple tree? How much is appropriate? How should you water?
Several main water-demand periods of the apple tree
(1) Bud break stage: soil moisture content should reach 70—80% of field capacity.
(2) Flowering stage: soil moisture content should reach 60—70% of field capacity.
(3) Critical period of flower bud differentiation: soil moisture content should reach 50%—60% of field capacity.
(4) Fruit enlargement stage: soil moisture content should reach 80% of field capacity.
(5) Ripening stage: soil moisture content should reach 80% of field capacity.
(6) Dormancy stage: soil moisture content should reach more than 80% of field capacity.
1. Bud break stage
In spring the apple tree buds and sends out shoots and forms flower buds, requiring more water. Spring drought often occurs at this time, so timely irrigation can promote spring shoot growth, enlarge leaves, raise flowering potential, and can also delay the phenological period to varying degrees, reducing the harm of spring cold and late frost. Generally, early to mid-March is suitable.
2. Before and after flowering
Excessive soil drought will make the apple flowering period come earlier and concentrated, with weak flowering potential and a low fruit-setting rate. Moderate irrigation before flowering gives good soil moisture during flowering and can significantly increase the fruit-setting rate. However, when soil moisture is already good before flowering, heavy irrigation is not suitable, otherwise it will make new shoots grow vigorously and compete for nutrients, lowering the fruit-setting rate. Watering after flowering helps cell division, makes fruit taller, and promotes new shoot growth. Generally, mid-to-late April is suitable, except in special years.
3. New shoot vigorous growth and young fruit enlargement stage
This is exactly the period of vigorous spring shoot growth and rapid cell division of young fruit, with a large water demand. At the same time, during this period the temperature keeps rising, evaporation is high, and leaf mass increases, so water demand surges. Be sure to maintain an adequate water supply, especially within one month after flowering; if water is lacking, it will cause symptoms such as small fruit, deformities, and lopsided fruit in apples. Therefore, if it is especially dry in this period, create the conditions to water once.
4. Flower bud differentiation stage
In this period the fruit tree needs less water; when there is too much water, it affects flower formation. If there is heavy rain, pay attention to drainage and drying the roots. If it is especially dry, water only half of the whole tree or spray water on the tree.
5. Fruit enlargement stage
The rapid fruit enlargement stage is the second critical period for water demand; the temperature is high, the leaf canopy is thick, the fruit expands rapidly, and the water demand is large. But at this time most fruit regions enter the rainy season, so generally no irrigation is needed, and attention should be paid to drainage and waterlogging prevention. Of course, the specific situation still needs to be judged by actual conditions. In this period, with high temperature, a thick leaf canopy, rapid fruit enlargement, and high water consumption, try to water once.
6. Before fruit harvest
In this period the temperature gradually drops, the water use of fruit and leaves decreases, and the air has a certain humidity, which is favorable for fruit coloring. But excessive water affects fruit coloring, and when moisture fluctuates greatly, it easily causes fruit cracking, so when it is dry in this period, you can spray water on the tree in the morning and evening, but do not pour large amounts of water. When there is heavy rain, be sure to pay attention to drainage or drying the roots.
7. After harvest until before leaf fall
This period is the key period for storing nutrients. Combining fertilization with watering is conducive to plump flower buds, so try to water heavily once.
8. Freezing water and dormancy stage
Water should be applied before the soil freezes in autumn, and the amount of water should be large. Before the aboveground part of the tree enters dormancy, the root system still has a period of growth. Watering sufficiently at this time will promote root growth, increase root absorption, and increase the nutrients stored in the tree. It can not only meet the water needs of the fruit tree during the relatively long dormancy period, but also prevent branch desiccation and freezing and tree freeze damage. This period has the lowest water demand, but a certain water supply is still needed.
Irrigation amount for apple orchards
The most suitable irrigation amount should, in a single irrigation, bring the soil moisture within the root distribution range to a level most favorable for fruit tree growth and development. Only moistening the surface soil or the soil in the upper root distribution layer cannot achieve the purpose of irrigation, and because of repeated supplementary irrigation, it easily causes soil compaction and lowers soil temperature. Therefore, it must be thoroughly irrigated in one go; for deep soil, one irrigation needs to wet the soil layer 50-60 cm or more.
The specific irrigation periods and irrigation amounts should be flexibly controlled according to weather conditions and tree growth conditions. In most cases, irrigation should be done from before bud break to the flowering stage, during new shoot growth and young fruit enlargement, during rapid fruit enlargement and flower bud differentiation, and from after harvest to the dormancy stage. Different tree types should also be treated differently: trees with strong growth vigor should be ensured an adequate water supply, while excessively vigorous trees should be appropriately water-controlled; in particular, water control during the vigorous new shoot growth period is conducive to controlling vigor and promoting flowering. For young vigorous trees, apart from irrigation before bud break and in autumn, as long as the leaves do not wilt during the vigorous new shoot growth period, no irrigation is needed. In addition, the irrigation amount should also be combined with the soil management method; covered orchards can appropriately reduce the irrigation amount.
Watering methods
1. Flood irrigation: letting water soak the whole orchard. This method is a lazy way that saves the labor of building beds, but it both wastes water and damages soil structure, so it is best not to use it.
2. Border irrigation or tree basin irrigation: densely planted apple orchards mostly build border strips along the tree rows, and when watering, irrigate border by border like watering vegetables. Sparse planting orchards mostly build tree basins with each tree as a unit, with separate water ditches, and when watering, water is led into the tree basin through the ditch. It saves water and is convenient to manage.
3. Furrow irrigation: In the apple tree rows, dig a furrow 20-30 cm deep and 40-60 cm wide at regular intervals, with about 1 m between furrows. When watering, lead water into the furrows and moisten the root distribution layer by infiltration. This neither damages the soil structure nor wastes water, and is a relatively ideal irrigation method.
4. Sprinkler irrigation and drip irrigation: Install sprinkler and drip irrigation equipment in the orchard, transport water through underground pipes, and use sprinkler heads to spray water (like rain) or drippers to moisten the soil. This saves water, does not damage soil structure, and can also improve the orchard microclimate; it is an advanced method. But the cost is relatively high, and it can only be done with strong economic means.