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10. Fusarium Wilt Disease
Fusarium wilt is a serious fungal disease that affects tomatoes, especially during the seedling stage. The pathogen's thick spores germinate and produce infection tubes that invade the root tips or wounds. Infected seedlings often die rapidly. In older plants, symptoms usually appear later, starting with yellowing and wilting of the lower leaves, which gradually moves upward. The midrib becomes permeable, and the vascular tissue in the cut area turns brown. As the disease progresses, the petioles droop, and the entire plant eventually dies.
Control measures include: (1) maintaining soil pH between 6 and 7; (2) planting resistant varieties; (3) using healthy seeds and seedlings to prevent disease spread through infected seeds.
11. Gray Spot Disease
Gray spot disease primarily affects the leaves and rarely impacts the fruit. Early symptoms include small yellow halos on the leaves, which later develop into numerous small spots. As the disease worsens, the center of the spots turns brown and breaks down, causing the leaf tissue to dry out and fall off. This can significantly reduce the plant’s health and productivity.
12. Silverleaf Whitefly (*Bemisia argentifolii*)
The silverleaf whitefly is a highly reproductive pest that spreads quickly. Adults lay eggs on the underside of tomato leaves, and the larvae feed on the plant sap. They go through four instars before reaching maturity. These pests not only damage the plant by sucking sap but also transmit the Tomato Leaf Curl Virus. Additionally, their honeydew secretions can lead to sooty mold growth, reducing photosynthesis and fruit quality. The peak activity period is from March to May and September to November.
Control methods include: (1) using yellow sticky traps or water traps to capture adult insects; (2) avoiding excessive nitrogen fertilization to prevent overgrowth; (3) applying insecticides such as 96% Edaphen solution diluted 1500 times, 2.8% Diflubenzuron emulsion at 1000 times, or 2% Abamectin emulsion at 1000 times, following the recommended safety intervals.
13. Tomato Fruitworm (*Helicoverpa armigera*)
The tomato fruitworm is a major pest that attacks all parts of the plant, including stems, leaves, flowers, and fruits. Larvae feed on the flowers and young fruits, disrupting pollination and leading to fruit rot. They often attack the base of the fruit, making it unmarketable. The larvae are known for cannibalistic behavior, and mature ones pupate in the soil. This pest is most active during the flowering and early fruiting stages, greatly affecting yield and quality.
Control strategies include: (1) using pheromone traps to attract male moths; (2) applying insecticides like 10.3% Trichoderma WP diluted 3000 times, 32.5% Sulfuramide Water Dispersible Emulsion at 1000 times, or 2.8% Diflubenzuron Emulsion at 1500 times, ensuring compliance with harvest safety periods.
14. Leafminer (*Liriomyza bryoniae*)
The leafminer is a common pest that causes significant damage to tomato leaves. Adults lay eggs inside the leaf tissues, and the larvae tunnel through the leaves, leaving characteristic white or gray trails. The damaged areas dry out, and severe infestations can result in scorched-looking foliage. The larvae then pupate in the soil. There are three peak infestation periods: during the seedling stage (2–5 leaves), and later during the fruiting phase.
Control measures include: (1) using yellow sticky traps or lures to catch adult flies; (2) applying insecticides such as 2% Abamectin emulsion diluted 2000 times, 24% Eprinomectin solution at 500 times, 2.8% Dichlorfen emulsion at 500 times, or 2.8% Spinetoram wettable powder at 5000 times, while observing safety and harvesting guidelines.
[V. Harvesting]
Harvesting of small cherry tomatoes should occur when the fruits are fully red and firm. In Taiwan, they are often sold fresh or preserved. Consumers judge freshness based on color, and high-quality cherry tomatoes should have a sugar content of at least 7 degrees. Early harvesting is recommended to avoid fruit drop or cracking.
[6. Precautions]
Semi-determinate tomato varieties may produce dwarf offspring due to genetic factors. The proportion of these plants varies depending on growing conditions and management practices. Dwarf plants can be removed at the seedling stage or managed through strong pruning and balanced nitrogen application. It is also important to choose fields with good drainage, fertile soil, ample sunlight, and proper ventilation to maximize yield and quality.
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