What are the latest control methods for pear black spot disease

Pears are full of moisture, 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, causing very large economic losses for friends who grow pear trees. What are these black spots? How can they be prevented effectively? 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 fruit skin 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 ruin the appearance, affect the aesthetic appeal, and make the fruit 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 the pear fruit needs a large amount of respiration. The temperature and humidity inside the bag increase, and this environment is even more favorable for the growth of the black spot disease pathogen. If continuous rainy weather occurs again, the air permeability 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 mealworms invade the pear fruit skin inside the paper bag and gnaw the skin, causing the immune system of the skin to fail, preventing it from absorbing nutrients, and turning the skin black. Pathogenic diseases such as Alternaria fungi also parasitize in soil and diseased plant debris, spreading through media such as rain and wind, affecting the development of the fruit skin. The last cause is bagging itself. Poor-quality bags, poor air permeability, and excessively high temperatures may cause necrosis of some cells in the fruit skin.

4. Control measures

When pear trees grow too tall and too large, prune the high branches reasonably and appropriately, strengthen the ventilation and light transmission of the orchard, disinfect the soil, and clean up diseased plant debris and diseased plants in a concentrated manner. Appropriately lower the temperature in the orchard and choose fruit bags of reliable quality. Professional data show that the highest incidence rate was with plastic film, as high as 55.7%, and the lowest was with double-layer non-waxed newspaper, with an incidence rate of only 7%. After bagging, set up several more ventilation openings in the fruit bag to ensure the temperature and humidity inside the bag. Spray pesticides before each stage of the pear tree for pest and disease control.

In fact, a large part of black spot disease is caused by improper management after bagging. Although black spot disease does not affect the flesh quality or taste of the pear fruit itself, the appearance of the pear fruit will be affected by the black spots. If it cannot be sold, it seriously threatens the economic interests of growers. Before and after bagging, all aspects must be properly organized to avoid black spot disease.