Prevention and Control of Pansy Virus Diseases and Pests
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July 17 07:29:58, 2025
Pansy is one of the most popular flowering plants in pots and garden beds due to its excellent weather tolerance, long blooming period, and attractive flowers. However, during cultivation, diseases and pests often occur, which can lower the quality and reduce the ornamental value of the plant.
1. Leaf Spot Disease:
This is a fungal disease that primarily affects the leaves, causing brown or pale white spots ranging from 0.2 to 0.5 cm in size with brown edges. The pathogen overwinters in infected plant debris or soil, and spores are spread by rain splash in early spring. High humidity and warm temperatures create ideal conditions for the disease to develop. Poor air circulation, low-lying areas, and dense planting can worsen the situation.
Control measures include avoiding low-lying areas and ensuring good airflow between plants. Seedbeds and growing media should be thoroughly disinfected, and the growing area should remain clean. If high humidity and temperature are present, regular monitoring is essential. Infected plants should be removed and destroyed immediately, and fungicides like 50% thiophanate-methyl, 800-fold sulfur suspension, or 40% chlorothalonil at 600 times concentration should be applied before symptoms appear.
2. Paint Spot Disease:
Another fungal disease, it causes irregular brown spots on leaves with yellowish halos and black specks that vary in size. The fungus is a weak parasite that survives in plant tissue and spreads through wounds, especially under humid or rainy conditions.
To manage this disease, proper watering practices should be followed to avoid overwatering. Good ventilation between plants helps reduce humidity. Infected plants must be removed promptly to prevent further spread. Before sowing, seedbed soil and containers should be disinfected using a 3:1 mixture of formaldehyde and water, covered with plastic for three days.
3. Mosaic Disease:
Caused by the Cucumber Mosaic Virus (CMV), this disease starts with small green patches between leaf veins, gradually spreading across the entire plant. Leaves may show mottled patterns, with some areas turning yellow while veins remain green. New leaves may grow slowly and become distorted. In severe cases, leaves curl upward, and small nodules form on the underside, along with brown veins. The overall growth of the plant slows down.
The virus overwinters in infected plants and spreads through sucking insects like aphids and leafhoppers. Outbreaks often coincide with peak insect activity.
To control mosaic disease, keep the growing area clean and remove nearby host plants of CMV, which includes over 100 species. Use resistant varieties and healthy seeds, and remove infected plants as soon as they are detected. Apply antiviral agents like 20% virus A powder diluted 500 times or 7.5g/7.5ml of water solution. Additionally, control aphids and leafhoppers using pesticides such as 40% dimethoate EC at 1000–1200 times or 2.5% cypermethrin EC at 2000 times. Early intervention is key to preventing widespread infection.