What to Do When There Are White Spots on the Rose Leaves
White spots on rose leaves often indicate a warning sign of plant health. This phenomenon is particularly common in household potted plants and garden cultivation, not only affecting the ornamental value but may also lead to the overall decline of the plant. This article will delve into the formation mechanism of white spot disease and provide a systematic solution.
Analysis of the Three Main Causes of Rose White Spot Disease
Double Dangers of Environmental Factors
Poor ventilation and high humidity are the main causes. Experimental data shows that when the air humidity is >75% and lasts for more than 3 days, the reproduction rate of pathogens will increase by 400%. Enclosed balconies or densely planted areas are more likely to become a breeding ground for pathogens.
Types of Pathogenic Infections
① Powdery Mildew: Initially presents as powdery white spots, later forming a grayish-white mycelium layer. ② Leaf Spot Disease: Produces circular or irregular white spots, often accompanied by brown edges. ③ Downy Mildew: White mold appears on the back of the leaves, corresponding to chlorotic spots on the front.
Five-Step Radical Treatment Guide
Key Points of Diseased Leaf Pruning Techniques
Use pruning shears sanitized with alcohol, and make an oblique cut 2cm away from the edge of the lesion. Note the different pruning standards for different diseases: • Powdery Mildew: Cut off the entire leaf and the adjacent 2 healthy leaves. • Leaf Spot Disease: Only remove the diseased leaf. • For severe infections, pruning of the entire branch is required, leaving 3-4 buds at the base.
Root Treatment and Soil Improvement
After removing the pot, use the running water method to clear the old soil, with the criteria for decayed roots being: • The epidermis is easy to fall off. • No white vascular bundles in the cross-section. • Has a sour smell. New soil should be mixed in the ratio of leaf mold soil: perlite: vermiculite = 5:3:2, and used after high-temperature sterilization.
Golden Combination of Pesticide Control
① Protective fungicide: 75% chlorothalonil 800 times solution (preventive spraying). ② Therapeutic fungicide: 25% pyraclostrobin 1500 times solution (used during the disease period). ③ Biological preparation: Bacillus subtilis solution (used alternately with chemical pesticides). It is recommended to use a leaf back-focused spraying method, twice a week for 3 weeks.
Daily Maintenance Prevention System
Establish a three-level defense mechanism: • Environmental control: Maintain a spacing of 50-70cm, set up a立体支架 to improve ventilation. • Water and fertilizer management: Use the siphon watering method, add potassium silicate to enhance disease resistance. • Monitoring and early warning: Conduct leaf transparency checks weekly, and deal with initial lesions immediately.
Through systematic control and scientific maintenance, the cure rate of rose white spot disease can reach 92% or more. It is recommended to establish a plant health record, recording each treatment measure and the plant's response, gradually forming a personalized maintenance plan.