How to prevent and control southern blight in lilies? A full analysis of the key methods
Symptoms: The whole plant wilts, white mycelial strands or rapeseed-like tan-colored small sclerotia wrap around the stem base, and the affected part turns brown and rots. Large amounts of white mycelial strands and tan-colored sclerotia are visible on the soil surface.
Pathogen: Sclerotium rolfsii Sacc., called the sclerotium-forming fungus, belongs to the Deuteromycotina fungi. The hyphae are white and silky, spreading in a fan-like or radial pattern, then gathering into mycelial strands or tangling into sclerotia. The sclerotia resemble rapeseeds, initially white to yellowish-white, later turning tan, round, with a smooth surface.
Transmission routes:
① The pathogen overwinters in the soil as sclerotia or mycelial strands on diseased plant debris. When conditions are suitable the following year, the sclerotia or mycelial strands produce hyphae for primary infection.
② The silky hyphae produced by diseased plants extend to contact neighboring plants, or the sclerotia spread through water flow for secondary infection, causing the disease to spread and expand. The disease is severe in continuous cropping, heavy clay soil, low-lying terrain, or in years or seasons with high temperature and humidity.
Control methods:
1. Avoid continuous cropping in heavily infested fields; crop rotation with cereal crops is best. Rice-upland rotation shows obvious control effects.
2. Inspect promptly. Pull out and burn diseased plants as soon as they are found. Drench the diseased holes and neighboring plants with a 1000-1600x dilution of 5% Jinggangmycin aqueous solution, or a 500-600x dilution of 50% Tianan aqueous solution, or a 1000x dilution of 20% tolclofos-methyl emulsifiable concentrate, or a 500x dilution of 90% dexon wettable powder, drenching 0.4-0.5 liters per plant (hole). Mix 15% fenaminosulf wettable powder, or 40% quintozene plus fine sand at a 1:200 ratio into medicinal soil and mix into the diseased soil, 100-150 grams per hole, once every 10-15 days.
3. When plowing, mix in ??00-150 kg of lime powder per mu to make the soil slightly alkaline, which can inhibit the reproduction of the southern blight pathogen.