With the arrival of May, the management of citrus becomes a heavy task, however, the most important is to preserve and stabilize the fruit. If you don't do well during this period, it will seriously affect the output, and even if you try harder, it may be in vain. At present, most citrus varieties have entered the second physiological fruit drop period, which lasts for a long time, from the end of April to July. The management of this period is directly related to the yield and appearance quality of the hanging fruit trees, so it is very important.
The second physiological fruit drop is the formation of a stratification between the base of the ovary and the fruit pedicle, that is, the physiological fruit drop without fruit stalk. Compared with the first physiological fruit drop, the number of fruit drop in the second time was significantly reduced, accounting for about 30% of the total number of fruit drops and about 25% of the total number of flowers. During this period, the main nutrient deficiency of the fruit is one of the main factors that lead to fruit shedding. When fruit trees lack sufficient carbohydrate supply, it can lead to malnutrition of the fruit, and even lead to an increase in the amount of abscisic acid and the release of ethylene, which can lead to the shedding of young fruits.
At present, the carbohydrates and nutrients of fruit trees come from three main sources: the nutrients stored by the tree last year, the absorption of soil nutrients by the roots, and the photosynthesis of leaves. However, all three aspects can be influenced by human or environmental factors. For example, if citrus trees are left for too long, resulting in excessive nutrient consumption and insufficient fertilizer and water, it will affect the nutrients stored in the tree. In addition, cold weather may affect the uptake of nutrients by roots, while continuous rainy weather can also affect leaf photosynthesis.
In addition, for citrus trees, May to June is the time when new shoots are growing vigorously, and it is also the season for summer shoots to be pumped. The growth and metabolism of new shoots are vigorous, and the competitiveness of nutrients is stronger than that of young fruits. Therefore, if young fruits lack an adequate supply of nutrients, they may stop growing and eventually fall off.
In order to preserve the results, we can take the following specific measures:
Measure 1: Apply fertilizer to stabilize the fruit
In the young fruit stage, fruit trees need appropriate fertilization, and the specific amount of fertilizer should be determined according to the specific conditions of the tree, spring shoot maturity, flower amount, fruit amount and so on. It is recommended to choose a high-potassium fast-acting fertilizer containing biostimulants to quickly replenish the nutrients needed for the development of young fruits. Compared with compound fertilizer, water-soluble fertilizer has a single nutrient and cannot meet the comprehensive nutritional needs of fruit trees at the young fruit stage, so it is not recommended to use it.
Measure 2: Spray fruit-preserving agents and foliar fertilizers
Foliar sprays such as brassin, gibberellic acid, and foliar fertilizers containing calcium, magnesium and other elements can be applied during the second physiological fruit drop stage. These measures can improve the hormone levels in citrus trees and inhibit abscisic acid activity, thereby reducing fruit shedding and promoting the development of young fruits. In addition, due to the need for essential elements in citrus trees, the addition of foliar fertilizers containing potassium, calcium, magnesium and other foliar fertilizers can reduce the synthesis of abscisic acid, and at the same time prevent problems such as yellowing of nutrient deficiency and cracking of young fruits.
Measure 3: Control the summer shoots
There are many ways to control summer shoots, including artificial wiping, pesticide control, etc. The choice of method should be reasonably selected according to factors such as the planting area of the orchard, the size of the fruit trees and the growth of new shoots. It should be noted that when using pesticides to control summer shoots, the concentration of pesticides should be strictly controlled, so as not to have a negative impact on the growth and development of young fruits.
Step 4: Prevent natural disasters
May is the season of rising temperatures and thunderstorms, and abnormal weather can make orchard management more difficult. The abnormal weather in May this year is relatively obvious, so it is necessary to pay close attention to the weather changes and take precautions against natural disasters. In rainy weather, the orchard should be drained in time to avoid rainwater accumulation affecting root growth and causing fruit to fall off. In hot and dry weather, timely irrigation is needed to keep it moist, and foliar fertilizers can be used to improve the stress resistance of the tree. High temperatures and droughts may affect the uptake of fertilizer and water by the roots and the growth of young fruits, resulting in abnormal shedding.
Measure 5: Do a good job of pest control
Citrus is susceptible to two major diseases in May, namely anthrax and resin disease. Especially after rain, anthrax is prone to outbreaks. In addition, it is necessary to pay attention to the prevention and control of aphids and red spiders. If a certain number of leafminer moths have appeared in the orchard, control measures should be taken in time to reduce the amount of occurrence in the later stage. When applying pesticides, it is necessary to avoid high temperature periods and rotate different types of pesticides at the same time to avoid the emergence of resistance.
In summary, May is a crucial period in citrus management, especially during the second physiological fruit drop period. By applying stable fruit fertilizer, spraying fruit preservation agents and foliar fertilizers, controlling summer shoots, preventing natural disasters, and doing a good job in pest control, the yield and fruit quality of fruit trees can be effectively improved to ensure a bumper harvest season.