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Long bean is a key to high yield, disease prevention and pest control
The long growth period of long beans occurs during the hot and rainy season, which creates favorable conditions for the development of diseases and pests. If proper management is not implemented, both the quality and yield of the crop can be significantly affected. To ensure safety and high-quality production, a combination of agricultural practices and chemical control should be used as preventive measures.
**1. Rust**
Rust typically appears between August and September, mainly affecting the leaves. Initially, yellow-green spots appear on the upper surface of the leaves, while small raised lesions develop on the underside. As the disease progresses, these spots turn reddish-brown and eventually become black. The infected leaves often scorch and fall off, reducing plant vigor.
**Prevention methods:** Ensure fields are level to prevent waterlogging. Remove crop residues after harvest and use fully decomposed organic fertilizer. Disinfect seeds with 1% potassium permanganate or 100 times diluted formalin, or treat with 50% carbendazim at 0.3–0.4% of seed weight. Apply fungicides like 75% Difenconazole (1000x) or 10% Trifloxystrobin (2000x), spraying 2–3 times.
**2. Virus Disease**
Symptoms include mosaic patterns, yellow spots, leaf curling, and stunted growth. Plants may fail to flower or wilt.
**Control methods:** Maintain soil moisture during dry periods. Remove weeds to eliminate virus vectors. Use insecticides like 10% Imidacloprid (2000–3000x) to control aphids, and apply antiviral agents such as Virusec or Zhilingling if infection occurs.
**3. Anthracnose**
This disease affects leaves, stems, and pods, causing brown, polygonal lesions. Petioles show red depressions, and pods have round brown spots that enlarge and turn pink.
**Control methods:** Improve cultivation practices, including proper planting density and application of phosphorus and potassium fertilizers. Spray with 25% Propiconazole, 10% Thiophanate-methyl, or 75% Micosazole, alternating between products and applying 3–4 times.
**4. Pod Borer**
The larvae of this pest feed on tender pods, flowers, and leaves, causing premature dropping of fruits and damage to beans. They also create tunnels in the pods, leading to rot after rain.
**Control methods:** Remove fallen flowers and damaged leaves to reduce infestation sources. Use black light traps to attract and kill adults. Apply insecticides such as 5% Chlorpyrifos (2000x), 40% Fenvalerate (6000x), or 2.5% Deltamethrin (3000x), spraying every 10 days.
**5. Leaf Miner**
The larvae tunnel inside the leaves, feeding on the upper and lower epidermis, causing visible trails and weakening the plant.
**Control methods:** Use pheromone traps to catch adult moths. Spray the underside of leaves where eggs are laid. At early stages, use 48% Emamectin Benzoate (800–1000x), applying 2–3 times.
**6. Red Spider**
Red spider mites thrive in hot and dry conditions, especially from August to September. They suck sap from young leaves, causing rapid defoliation.
**Control methods:** Immediately spray a pesticide barrier around the infested area, covering slightly beyond the affected zone. Use pesticides such as Acequinocyl, Petroleum Oil, or Avermectin (e.g., Abamectin). Apply 10% EC at 50–100 ml per acre, mixed with 1000–1500 times water, ensuring even coverage.