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10. Fusarium Wilt
Fusarium wilt is a serious soil-borne disease caused by the fungus *Fusarium oxysporum*. The pathogen enters the plant through the roots, often via wounds or root tips, and spreads into the vascular system. In seedlings, it can cause rapid wilting and death. In mature plants, symptoms usually appear later, starting with yellowing and wilting of the lower leaves, which gradually progresses upward. The midrib may become permeable, and the vascular tissue in the cut stem shows visible browning. The petioles droop, and eventually, the entire plant dies.
Control measures include: (1) maintaining a soil pH between 6 and 7; (2) planting resistant tomato varieties; (3) using disease-free seeds and seedlings to prevent transmission through infected seeds.
11. Gray Spot Disease
Gray spot disease primarily affects the leaves of tomatoes, not the fruits. Initially, small yellow halos appear on the leaves. As the disease progresses, numerous small spots develop, and the center of the lesions turns brown and becomes necrotic. This causes the leaves to dry out, turn brown, and fall off. The disease often starts on one side of the plant and can spread quickly under favorable conditions.
12. Silverleaf Whitefly (*Bemisia argentifolii*)
The silverleaf whitefly is a common pest that reproduces rapidly and has a wide host range. Adults lay eggs on the underside of tomato leaves, and the larvae feed on plant sap. They go through four instars before becoming adults. These pests not only suck plant fluids but also transmit the Tomato Leaf Curl Virus. Additionally, they secrete honeydew, which promotes sooty mold growth. This reduces photosynthesis and fruit quality, and in severe cases, can lead to crop failure. The peak infestation periods are from March to May and September to November.
Control methods include: (1) using yellow sticky traps or water traps to capture adult whiteflies; (2) avoiding excessive nitrogen fertilization to prevent lush growth that attracts pests; (3) applying insecticides such as 96% Edamine solution diluted 1500 times, 2.8% Diflubenzuron emulsion at 1000 times, or 2% Abamectin emulsion at 1000 times, following label instructions and safe harvest intervals.
13. Tomato Fruitworm (*Helicoverpa armigera*)
The tomato fruitworm, also known as the cotton bollworm, is a major pest affecting both the foliage and fruit. Adult moths feed on nectar, while the larvae feed on stems, leaves, flowers, and fruits. The most damaging stage occurs when larvae feed on young or mature fruits near the pedicle, causing rot and rendering the fruit unmarketable. Larvae also exhibit cannibalistic behavior. The peak infestation period is during the flowering and early fruiting stages, significantly impacting yield and quality.
Control options include: (1) using pheromone traps to attract and reduce male moths; (2) applying insecticides such as 10.3% Trichoderma WP diluted 3000 times, 32.5% Sulfuramid Water Dispersible Emulsion at 1000 times, or 2.8% Diflubenzuron Emulsion at 1500 times, following safety guidelines and harvest intervals.
14. Leafminer (*Liriomyza bryoniae*)
The leafminer is a small fly that lays eggs inside tomato leaves. The larvae feed between the upper and lower epidermis, creating winding tunnels that appear as white or gray streaks. This feeding damages the leaves, leading to drying and loss of turgor. After completing their development, the larvae drop to the soil to pupate. There are three peak infestation periods: early seedling stage (2–5 leaves), middle growth phase, and late fruiting stage. Severe infestations can cause extensive leaf damage and reduce yield.
Control methods include: (1) using yellow sticky traps to catch adult flies; (2) applying insecticides such as 2% Abamectin emulsion diluted 2000 times, 24% Eprinomectin solution at 500 times, 2.8% Dichlorvos emulsion at 500 times, or 2.8% Spinetoram wettable powder at 5000 times, ensuring proper application and safety.
[V. Harvesting]
For small cherry tomatoes, harvesting should occur when the fruits are fully red and firm. In Taiwan, fresh tomatoes are often sold as preserved products. Consumers typically judge freshness based on color. 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 plants due to genetic factors. The proportion of these plants varies depending on growing conditions and management practices. Dwarf plants can be removed or pruned early. Strong pruning, along with appropriate nitrogen fertilizer application, can help improve plant vigor. It’s also important to select fields with high groundwater levels, good drainage, fertile soil, ample sunlight, and good air circulation to maximize yield and quality.
ARM CMM
Arm Portable CMM
Arm Portable CMM
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