Prevention and Control of Pansy Virus Diseases and Pests
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July 17 07:15:44, 2025
Pansy is one of the most popular flowering plants, widely grown in pots and garden beds due to its strong weather resistance, long blooming period, and attractive flowers. However, during cultivation, diseases and pest infestations can significantly impact its quality and ornamental value.
1. **Leaf Spot Disease**
This fungal disease primarily affects the leaves, causing brown or pale white spots that are round in shape, ranging from 0.2 to 0.5 cm in diameter, with distinct brown edges. The pathogen overwinters in infected plant debris or soil, and in spring, spores are spread by rain splash, leading to new infections. High humidity and warm temperatures create ideal conditions for the disease to develop. Poor air circulation, low-lying planting areas, and dense planting can worsen the problem.
Control measures include avoiding low-lying areas, ensuring good ventilation between plants, and thoroughly disinfecting seedling and growing media. If symptoms appear early, remove and destroy infected plants immediately, and apply fungicides such as 50% thiophanate-methyl at 800 times dilution or 40% chlorothalonil suspension at 600 times. These treatments are most effective when applied before symptoms become severe.
2. **Paint Spot Disease**
Another fungal infection, this disease causes irregular brown spots on leaves, often surrounded by yellowish areas. Black spots may also appear over time. The fungus typically infects through wounds and thrives in humid or rainy conditions.
To manage this disease, avoid overwatering and improve air circulation around plants. Promptly remove and isolate any infected plants to prevent further spread. Before planting, disinfect the soil using a 3:1 mixture of formaldehyde and water, cover it with plastic for three days, and then aerate before use.
3. **Mosaic Disease**
Caused mainly by the Cucumber Mosaic Virus (CMV), this disease begins with mottled green patches on the leaves, which later expand into yellow-green or green-yellow patterns. The veins remain green, and the new leaves may grow slowly or show distorted growth. In severe cases, leaves curl upward, and small nodules appear on the leaf backs, along with brown veins. The virus overwinters in infected plants and spreads through aphids and leafhoppers.
To control mosaic disease, keep the growing area clean and remove nearby host plants that can harbor the virus. Use resistant varieties and healthy seeds. Remove any infected plants as soon as they are spotted. Apply virus inhibitors like 20% virus A powder diluted 500 times or 7.5g of virus control agent per liter of water. Additionally, control aphids and leafhoppers using insecticides such as 40% dimethoate EC diluted 1000–1200 times or 2.5% cypermethrin EC diluted 2000 times.
By following these practices, gardeners can effectively reduce the risk of disease and maintain healthy, vibrant pansies throughout the growing season.