How to prevent and control damping-off disease in green plants and flowers at the seedling stage?

Seedling-stage diseases of flowers mainly occur during the seedling stage of flower plants. Annual herbaceous flowers often cause seedlings to suddenly collapse; seedlings of perennial flowers and the stems of W-flowers and flowers cause damping-off before the stems reach quality. The disease has multiple parasitic pathogens.

Dangerous symptoms

Seeds or branches become infected and rot when not yet unearthed. At the seedling stage, the stem surface below the surface or below the soil surface shows water-soaked lesions. The affected parts turn yellowish-brown and shrink, and can extend to the upper and lower parts of the plant and become linear. The disease develops rapidly, tissues disintegrate, and seedlings wilt, but the leaves remain green in the short term. If the environment is humid, the pathogen and the nearby soil surface produce a white cotton-like dense mycelial layer.

Prevention and treatment measures

1. Improve seedling-raising measures: choose a place with high terrain, dryness and good drainage as the seedbed; apply fully decomposed fertilizer or use high-quality cultivation soil; control the amount of irrigation at the seedling stage, and the soil should not be too wet; sow in time, do not let seedlings be affected by impermeable humidity; flowers should be cut and propagated, and the slices should be slightly dried to promote wound healing; sowing should not be too dense; seedlings should keep the seedbed well ventilated; diseased buds should avoid continuous cropping or the soil should be disinfected before replanting. Implement excellent seedling cultivation, cultivate strong seedlings, and enhance disease resistance.

2. Soil and substrate disinfection and fumigation: 2 to 3 weeks before sowing or cutting, sterilize with 40% stagnant formalin, 40 to 50 ml per square meter of seedbed, 50 (when moist water) to 200 (dry soil) times, spray or pour evenly, immediately cover the soil surface with plastic film or woven bags, and remove it after 5 to 7 days. It is better to loosen the topsoil to promote gas volatilization. After 1 to 2 weeks, the smell of the medicine has completely dissipated. You can plant it. Substrate disinfection: use 300 to 500 ml of formalin per cubic meter, dilute with water, apply evenly, pile up, cover with film, remove the film after 2 days and one night, and apply soil and gas. Soil application: before sowing, apply one of the following medicines to the bed surface or substrate surface: 65% dikesone, 40% seedlings (for resistance to fusarium wilt, add the same amount of fu-mei-shuang), 50% dry, 65% da-xian-zinc, 650% carbendazim, 75% chlorothalonil, 40% ethyl phosphorus aluminum, 40% seed dressing double, pentachloronitrobenzene plus fu-mei-shuang or mixed seedlings, 25% frosting plus 70% mancozeb 9:12 mixed, the above agents are used at 8 to 10 grams per square meter, add 3 to 5 kg of fine dry soil, mix with soil or mix with topsoil, or sow 1/3 of the soil before sowing, and cover the seeds with 2/3 after sowing. The medicine can also be mixed into the substrate nutrient soil, adding 40-60 grams of the above reagents per cubic meter of substrate, mixing the mixture and stacking for 1-2 days.

3. Chemical control: in the early stage of the disease, spraying fungicides can effectively control the outbreak. Commonly used fungicides include 50% carbendazim wettable powder 500 times solution, 25% metalaxyl wettable powder 800 times solution, 40% ethyl phosphorus aluminum wettable powder 200~400 times solution, or 25% luomycin 600 times solution spray, 75% chlorothalonil wettable powder 600 times solution, etc.