How to prevent melon leaf spot disease? Melon leaf spot control method? Leaf spot disease is one of the important diseases of melon, which is widely distributed and occurs everywhere. It is generally heavier in spring and autumn. The incidence rate is 10%-60%, and 100% of the serious plots or sheds can be reduced by 10%-30%. In severe cases, the yield can be reduced by more than 60%. The disease can also be harmful to cucumbers, melons, loofah, bitter gourd and other vegetables.
Melon leaf spot symptoms: This disease is harmful to leaves, stems, melons, and the damage to leaves is more serious. It can occur in all growth stages of melon. The cotyledon is damaged by a water-soaked, nearly circular depression, which turns yellowish brown. The true leaves are damaged, initially oil-immersed, gradually turning into a pale brown polygon to a nearly circular spot. The edge often has a rust yellow oil-immersed ring, and finally is translucent and ruptures when dry. When the air is wet, the lesions overflow with light yellow brown pus. Fruits and stems are infected, the lesions are oil-immersed, dark green, cracked or ulcerated in severe cases, overflowing the bacterial liquid. When the fruit is infested, the germ can spread all the way to the seed and cause the seed to be sterilized.
The pathogenesis of melon leaf spot disease: The pathogen is overwinter in the soil or in the soil with the diseased body. Invasion through wounds or stomata, water holes and lenticels, spread by rain, watering, insects and condensation after onset. The growth temperature of the pathogen is 1-35 ° C, the development temperature is 20-28 ° C, the growth stops at 39 ° C, and death occurs at 49-50 ° C. High air humidity, or rainy, or condensation at night is more conducive to disease.
Melon leaf spot control method:
1. Select disease-free seeds, soak seeds for 50 minutes with 50-52 °C warm water before sowing. Or use 47% of the seed weight of 0.3% of the Rinong WP powder for seed dressing.
2. Raise seedlings with disease-free soil, and thoroughly remove the diseased deciduous and non-cucumber crops after 2 years of rotation.
3. Reasonable watering to prevent flooding of large water, protective ground should pay attention to ventilation and dehumidification, shorten the surface condensation time of the plant, pay attention to the agricultural operation after the dew is dry, and timely control the pests in the field.
4. Chemical control. In the early stage of the disease, 5% of the fungicide can be used to control the powder of 15 kg/ha. Can also use 47% garnip WP 800 times solution, or 50% can kill WP 500 times solution, or 25% dithianon plus alkaline copper chloride 500 times solution, or 25% thiabate 300 times solution of azole, or spray with neomycin 5,000 times solution.
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