What are the control methods for lily wilt disease

Latin scientific name: Fusarium oxysporum f. sp. lili Snyder et Hansen

Crops affected: lily

Symptoms: Also known as stem rot, it is an important disease in lily production. Infected plants initially show slow growth, and the lower leaves turn yellow and lose their luster; afterward the symptoms gradually spread upward, and finally the leaves of the whole plant wilt and droop, turn brown, and die. In addition, Fusarium oxysporum f. sp. lili can also infect the base of the outer scales of the bulb, where brown necrosis or rot appears on the basal plate, causing the scales to fall apart. Plants growing from diseased bulbs have yellow or purplish leaves, few and small flower stems, and the bulb splits open before it has completely rotted, causing the bulb to rot and then die.

Morphological characteristics of the pathogen: macroconidia are crescent-shaped, with 3-5 septa, measuring 17.5-21 x 3.5-4.9 (micrometers). F3 aerial mycelium is dirty white, the colony is sparse, flat and mucoid; microconidia are long ovoid, with 0-1 septum, pointed at one end and blunt at the other, measuring 6.3-12.6 x 2.8-4.9 (micrometers); macroconidia are crescent-shaped, with 2-4 septa, with tapering ends, measuring 17.5-35 x 2.8-7 (micrometers). Fusarium moniliforme on PSA medium first forms white fluffy round colonies; the pathogen grows rapidly on the medium and later produces purple pigment. Sometimes orange sporodochia may be produced. The surface of the substrate is morning-glory purple, and the medium does not change color. The pathogen produces two types of conidia, large and small. Macroconidia are spindle-shaped to sickle-shaped, straight or slightly curved, mostly with 3-5 septa; those with 3 septa measure 25-55 x 3-4.5 (micrometers). Microconidia are numerous, oval to elliptical, borne in chains on the conidiogenous cells, and also in false heads. A few have 1 septum, measuring 7-11.5 x 2-3 (micrometers). Fusarium solani sporodochia are cushion-like and brightly colored; conidia are borne on the sporodochia, with two types of conidia, large and small. Macroconidia are sickle-shaped, colorless, multicellular, and septate; microconidia are ovoid, unicellular, and colorless; later the hyphae gather to form black sheet-like sclerotia.

Taxonomic attribute: Deuteromycete fungi

Disease characteristics: The pathogen overwinters as mycelium in the bulb or as mycelium and sclerotia with diseased residues in the soil, becoming the primary infection source the following year. This disease often occurs together with other underground root rots and scale rots of lily; diseased bulbs and contaminated soil are the main infection sources of the disease. The disease is prone to occur after flowering when temperatures are high and rainfall is abundant, and it is more severe with continuous cropping and when there are many wounds caused by damage from underground pests and root-knot nematodes.

Control methods: (1) Implement crop rotation. (2) Apply Baode biological fertilizer or compost fermented with enzyme bacteria, apply less ammoniacal nitrogen fertilizer, and apply more phosphorus and potassium fertilizer to enhance disease resistance. (3) Select disease-free, uninjured bulbs as propagation material. (4) Before planting, soak the bulbs in a mixture of 40% quintozene 200-fold solution plus 50% thiram 200-fold solution for 15 minutes, or soak them in 50% benomyl wettable powder 2000-fold solution at 30°C water temperature for 30 minutes; the bulbs can also first be treated with 39°C warm water for 2 hours, then soaked in 50% benomyl 2000-fold solution for 30 minutes. A 43% formalin 120-fold solution can also be used to soak the seed for 3.5 hours, with obvious control effect. (5) Spray 36% thiophanate-methyl suspension concentrate 500-fold solution or 50% thiophanate-methyl sulfur suspension concentrate 800-fold solution, 50% benomyl wettable powder 1000-fold solution, 12.5% synergistic carbendazim concentrated soluble liquid 300-fold solution, or 50% Shajunwang (chlorobromoisocyanuric acid) water-soluble powder 1000-fold solution.

Commonly used pesticides: thiophanate-methyl, sulfur, synergistic carbendazim