Methods for preventing and treating Fusarium wilt in melons, a must-read for growers
Symptoms This disease can occur throughout the entire growth period of melons. When seedlings are infected, the leaves of the diseased seedlings become lighter in color, gradually wilt, and finally die. When the stem is cut open, the vascular bundles can be seen to have discolored. When the disease occurs during the mature plant stage, the leaves of the plant wilt and droop from bottom to top, some leaf edges turn brown or produce brown necrotic spots, and finally the whole plant dies. Sometimes sunken necrotic streaks also appear on the diseased stems. When the air is humid, a white to pink mold layer forms on the surface of the diseased parts, and finally the base of the diseased stem rots and splits longitudinally, and the vascular bundles turn brown.
Disease conditions This disease is caused by the imperfect fungus Fusarium sp. The pathogen mainly overwinters as mycelium and chlamydospores in soil, diseased residues, or uncomposted fungal fertilizer. When conditions are suitable, the pathogen enters through root wounds or directly between the meristematic cells at the root tip, forming an initial infection. When the soil temperature is 15-20°C, melon root growth is poor and wounds are difficult to heal, so the pathogen easily invades. Continuous cropping allows the pathogen to accumulate continuously, making the disease more severe. Slightly acidic soil, heavy clay texture, low-lying waterlogged terrain, application of uncomposted fertilizer, and abundant underground pests all favor disease development.
Key control points
1. Rotate crops and change fields, preferably rotating with cruciferous or liliaceous vegetables. According to the pathogenic characteristics of the pathogen, in areas with severe disease, black-seeded pumpkin can be used as rootstock and obliquely grafted with melon scions to prevent the disease.
2. Use high ridges with plastic film mulching, or water-saving cultivation techniques such as drip irrigation.
3. Apply fully composted organic fertilizer to reduce root injury. Water lightly, and pay attention to timely shallow intertillage after watering.
4. Before sowing or transplanting, use 50% carbendazim wettable powder, or 50% procymidone wettable powder, or 70% hymexazol wettable powder 2-3 kg/667 sq m with 50-60 kg, applied in furrows or holes. Alternatively, use 15% shuangxiaoling aqueous solution at 1500 times dilution, or 65% dodine wettable powder at 1000 times dilution, or 25% propiconazole emulsifiable concentrate at 3000 times dilution, or 45% thiabendazole suspension at 1000 times dilution, or 30% hymexazol aqueous solution at 600 times dilution, or 50% carbendazim wettable powder at 500 times dilution to drench the planting holes, 0.25 kg per hole of solution. In the early stage of disease onset, the above agents at the same concentration can also be used to drench the roots, with 0.25-0.5 kg of solution per plant.