Prevention and Control of Diseases and Pests of Chinese bleeding heart
The Chinese bleeding heart, with its unique heart-shaped flowers, is deeply loved by gardening enthusiasts, but issues with leaf diseases and pests often trouble growers. This article delves into two common diseases and pests, providing a systematic control plan.
Comprehensive Control of Leaf Spot Disease in Chinese bleeding heart
Characteristics and Transmission Mechanism of the Disease
Initially, leaves develop dark brown spots measuring 0.5-2mm, which develop into 3-8cm irregular brown patches as the disease progresses. Black mold-like substances appear when humidity is above 75%. Pathogen spores are spread through splashing irrigation water, and a single infected plant can spread to nearby plants within 3-7 days.
Environmental Inducing Factors
The disease is most likely to break out with an average daily temperature of 20-28°C combined with consecutive rainy and cloudy days. Plant resistance decreases by 30%-45% when soil pH is less than 6.0 or greater than 7.5. Experimental data show that excessive application of nitrogenous fertilizer increases the incidence rate by 2.3 times.
Three-Level Prevention and Control System
• Prevention stage: Spray a 1:1:200 Bordeaux mixture in the spring germination period, repeating the treatment every 20 days• Early control: Immediately spray 50% carbendazim 800 times liquid on diseased leaves, while supplementing potassium dihydrogen phosphate to enhance resistance• Severe case treatment: Alternately use 25% azoxystrobin suspension 1500 times liquid and 10% difenoconazole water-dispersible granules 2000 times liquid
Ecological Control of Scale Insects on Chinese bleeding heart
Key Points for Pest Identification
The adult female insect is 2-3mm long and elliptical in shape, with 3-4 generations per year, and the peak hatching period is in early May. Infested plants can experience a 40%-60% reduction in photosynthetic efficiency, and secretions cause sooty mold, leading to a leaf shedding rate of up to 80%.
Biological Control Plan
Release a combination of ladybugs (Cryptolaemus montrouzieri) and parasitic wasps (Aphytis melinus) at a ratio of 1:50. Ladybugs can eat up to 60 nymphs per day, and parasitic wasps have a parasitism rate of 92% on 2nd instar nymphs.
Chemical Control Timing
The best control period is during the peak hatching period of nymphs (May 10-20), using 22% flonicamid suspension 4000 times liquid plus an organic silicone additive, focusing on the back of the leaves. During the winter cleanup, use a 29% lime sulfur mixture 100 times liquid to treat the branches and trunks.
Key Points for Comprehensive Maintenance Management
Environmental Control Standards
Maintain a plant spacing of ≥50cm to ensure air circulation rate > 0.5m/s. Keep the summer shading rate at 30%-40% and maintain the soil EC value at 1.2-1.8mS/cm. Apply decomposed organic fertilizer (N-P-K=3-1-2) monthly to enhance plant immunity.
By implementing a strategy combining precise identification of diseases and pests, ecological regulation, and chemical control, the incidence of diseases and pests in Chinese bleeding heart can be effectively reduced. Regular inspections and preventive treatments are key. It is recommended to establish a disease warning log to record temperature and humidity changes and control effects, achieving scientific maintenance management.