Identification and Control Methods of Paecilomyces lucidus Disease

Paecilomyces belongs to the subphylum Deuteromycotina, class Hyphomycetes, order Hyphomycetales, family Hyphomycetaceae, genus Paecilomyces. The species commonly found in production is Paecilomyces variotii (p.varictBainier).

1. Morphological characteristics: The hyphae are white, transparent, and septate. The colony is earthy yellow and is often mistaken for Aspergillus flavus, commonly called yellow mold by mushroom growers. Conidiophores arise from aerial hyphae or cord-like hyphae; the phialides are slender and elongated, swollen at the base, tapering to a pointed tip, often curved, single to broom-like branched. Conidia are short cylindrical to long elliptical, smooth, arranged in chains, and some strains produce giant spores.

2. Disease development pattern

(1) Transmission routes: Widely distributed in soil, air, and various substrates, it has strong corrosive ability and can corrode electrical materials, rubber, plastics, and other polymer materials. Spores spread through air currents, and infections frequently occur in large numbers during spawn production and bag cultivation.

(2) Occurrence conditions: Paecilomyces is suited to moderate temperature and moderate humidity environments. Unsanitary cultivation sites and poor ventilation are the main conditions for disease occurrence.

3. Damage symptoms: It grows rapidly on PDA medium. The hyphae are initially white, then conidia are gradually produced from the center of the colony to the edge, causing the colony to change from light yellow to an earthy yellow powdery mold layer. It grows rapidly in the substrate, appearing earthy yellow and loose cotton-like. It grows quickly, generally completing one generation in 3 days. The colony is of the spreading type, and once contaminated it quickly occupies the entire substrate layer, causing complete failure of both spawn expansion and cultivation.

4. Control methods

(1) Do good sanitation work; spray the site with 500 times 70% thiophanate-methyl for sterilization at irregular intervals.

(2) Pay attention to ventilation in the culture room and keep the air dry. Before placing spawn bags on the culture shelves, a layer of fungicide dry powder should be sprinkled on them to prevent the occurrence of contaminant microorganisms.