Unveiling the mystery of why the leaves of the贴梗海棠 turn black and fall, along with the causes and control measures. (Note: "贴梗海棠" is a specific type of flowering plant, which can be translated as "Hydrangea macrophylla" or "big-leaf hydrangea" if it is the intended species. However, without the exact species, it is kept in Chinese.)

Reasons and Control Measures for Blackening and Defoliation of Flowering Crabapple Leaves

Flowering crabapple, also known as Japanese quince, is an ornamental plant with extremely high decorative value. In recent years, many flowering crabapple plants have shown symptoms of blackening leaves and defoliation, which severely affects their ornamental value and growth. This article will uncover the mysteries behind the blackening and defoliation of flowering crabapple leaves and provide corresponding control measures.

Reasons for Blackening and Defoliation of Flowering Crabapple Leaves

1. Disease Factors

(1) Anthracnose: Anthracnose is one of the main causes of blackening and defoliation in flowering crabapple leaves. After the pathogen invades the leaves, it causes black spots to appear, which gradually expand, eventually leading to leaf withering and falling off.

(2) Leaf Spot Disease: Leaf spot disease is also a common ailment that can cause black spots on flowering crabapple leaves, with severe cases leading to leaf withering and defoliation.

2. Pest Factors

(1) Aphids: Aphids are one of the main pests affecting flowering crabapple, which suck the sap from the leaves, causing them to blacken and wither.

(2) Spider Mites: Spider mites can infest flowering crabapple leaves, leading to yellow spots, withering, and in severe cases, defoliation.

3. Environmental Factors

(1) Insufficient Light: Flowering crabapple requires ample sunlight. Insufficient light can lead to blackening and defoliation of leaves.

(2) Improper Water Management: Excess or insufficient water can both cause blackening and defoliation of flowering crabapple leaves.

Control Measures for Blackening and Defoliation of Flowering Crabapple Leaves

1. Disease Control

(1) Strengthen Plant Management: Timely removal of diseased leaves and branches to reduce the spread of pathogens.

(2) Rational Fertilization: Applying organic fertilizers to enhance the plant's resistance to diseases.

(3) Chemical Control: During the early stages of the disease, fungicides such as carbendazim and mancozeb can be used for control.

2. Pest Control

(1) Physical Control: In the early stages of pest infestation, manual removal of aphids and spider mites can be carried out.

(2) Biological Control: Utilizing biological control methods with natural enemies such as beneficial insects and microorganisms to reduce pest occurrence.

3. Environmental Regulation

(1) Light: Ensure that flowering crabapple receives ample sunlight to prevent blackening and defoliation of leaves.

(2) Water Management: Water appropriately based on soil moisture to avoid excessive or insufficient water.

The reasons for blackening and defoliation of flowering crabapple leaves are numerous, including diseases, pests, and environmental factors. Understanding these reasons allows us to take appropriate control measures to ensure the normal growth of flowering crabapple. I hope this article is helpful to you.