How to Solve Pear Black Spot Disease? Detailed Explanation of Prevention and Control Methods
Pears are full of water, crisp and delicious, and help clear heat and detoxify, relieving fatigue. However, many friends often find many black spots on the surface of pears while growing pear trees. These black spots can seriously affect the growth and development of pear trees and cause very large economic losses to those growing pears. What are these black spots? How can they be effectively prevented? Let's take a look below.
1. Disease Symptoms
These black spots are generally called black spot disease, and black spot disease generally occurs on bagged pears. In the early stage of the disease, black spots of various sizes appear on the surface of the pears. These black spots gradually spread, and finally many spots spread together to form patches. However, these black spots only damage the peel and have no effect on the flesh or leaves, nor do they affect the taste, and they will not cause problems with the flesh. Although none of these have any effect, they damage the appearance, affect the aesthetic appeal, and make the pears impossible to sell.
2. Disease Pattern
If young fruit is infected before bagging, the disease will not develop. It generally begins around the Start of Summer, and the pear fruit expansion period begins in July, when pear fruit needs a large amount of respiration. The temperature and humidity inside the bag increase, and this environment is more favorable for the growth of the black spot disease pathogen. If continuous rainy weather occurs again, the ventilation inside the bag drops severely, leading to an increased and more severe incidence of black spot disease. Excessively high temperature and humidity in the paper bag will lead to a higher incidence of black spot disease.
3. Causes of the Disease
There are many causes of the disease. For example, pests such as yellow mealworm invade the peel of pear fruit inside the paper bag and gnaw on the peel, causing the peel's immune system to fail, preventing it from absorbing nutrients, and turning the peel black. Pathogenic fungi such as Alternaria also parasitize the soil and diseased plant residues, spread through media such as rain and wind, and affect peel development. The last cause is bagging itself, possibly because the quality of the bag is poor, the ventilation is poor, and excessively high temperature causes partial cell necrosis of the peel.
4. Prevention and Control Measures
When pear trees grow too tall and too large, the high branches should be pruned reasonably and appropriately, the ventilation and light penetration of the orchard should be strengthened, the soil should be disinfected, and diseased plant residues and infected plants should be centrally cleaned up. Appropriately lower the temperature in the orchard and choose fruit bags of reliable quality. Professional data show that the highest incidence rate is with plastic film, at 55.7%, and the lowest is with double-layer non-waxed newspaper bags, at only 7%. After bagging, add several ventilation openings to the fruit bag to ensure the temperature and humidity inside the bag. Spray pesticides before each stage of the pear tree for disease and pest control.
In fact, a large part of black spot disease is caused by improper management after bagging. Although black spot disease does not have much effect on the flesh quality or taste of the pear fruit itself, the appearance of the pear fruit will be affected by the black spots. If they cannot be sold, this seriously threatens the economic interests of growers. Before and after bagging, all aspects must be properly arranged to avoid the occurrence of black spot disease.