What are the control methods for lily blight?

Symptoms: The entire plant (including flowers, leaves, stems, stem base, bulbs, and roots) can be affected. Infected flowers wither and fade, with white mold growing on them; leaves initially show water-soaked spots, then wither; stem and stem base tissues initially show water-soaked spots, then turn brown, necrose, and constrict, with all parts above the infected area completely withering. Bulbs turn brown and necrose. Roots turn brown and rot. Pathogen: The pathogen is Phytophthora parasitica Dast, a fungus of the genus Phytophthora in the phylum Mastigomycotina. The hyphae are colorless and non-septate. No haustoria are produced; the hyphae directly penetrate the host cells to absorb nutrients. In later stages, hyphae and numerous sporangia are produced. The sporangiophores are mostly unbranched, and the sporangia are terminal, single-spored, and round. There is a papilla at the tip. When the sporangia germinate, they produce multiple oval zoospores.

Transmission routes:

1. The pathogen mainly overwinters as oospores in the soil with diseased plant debris. The following year, the oospores splash onto plants with rain or irrigation water, germinate, and the germ tubes invade the host and cause damage.

2. Later, the lesions produce large numbers of sporangia, and the sporangia produce zoospores, which spread and cause damage via rain, irrigation water, and other means.

Disease conditions: Infected bulbs, continuous rainfall, poor drainage.

Control methods:

1. Select healthy bulbs; install rain shelters and pay attention to drainage.

2. Before the rainy season arrives, protect with fungicides. In the early stage of disease, use 25% metalaxyl 800x solution; 58% metalaxyl mancozeb 500x solution; 40% fosetyl-aluminium 200x solution; 64% oxadixyl wettable powder 500x solution; or 77% copper hydroxide wettable fine powder 500x solution. Spray once every 7-10 days, for 2-3 consecutive sprays. Alternatively, at the beginning of disease onset, promptly spray 72% cymoxanil mancozeb (Kekangling) wettable powder 800x solution, or 72% DuPont Curzate or 72% cymoxanil wettable powder 800-1000x solution, or 56% Kaoshan water-dispersible microgranules 800x solution.