How to Prevent and Control Penicillium Mold in Oyster Mushrooms? A Detailed Guide to Practical Techniques

Penicillium Penicillium is a common contaminant mold on oyster mushroom spawn-production and cultivation beds, and occasionally has a weak parasitic effect on fruiting bodies; its asexual stage belongs to the Deuteromycotina, genus Penicillium.

(1) Pathogen characteristics: Penicillium hyphae are colorless, septate; the colony is initially white, with most of it penetrating deep into the substrate and few aerial hyphae, appearing as a felt-like or cottony mass; the conidiophores branch in a broom-like pattern at the tips, and when conidia accumulate in large numbers they form a blue-green, yellow-green or blue-green powdery mold layer.

(2) Damage symptoms: In the early stage of Penicillium occurrence, white or yellowish-white felt-like colonies appear on the contaminated area, and after 1~2d they gradually turn into a light green or light blue powdery mold layer, with a white outer ring; the mold layer spreads relatively slowly and grows in a limited area, and is often overgrown by vigorous oyster mushroom hyphae. When Penicillium contamination occurs, in addition to competing with oyster mushroom hyphae for nutrients and water, it can also block air at the substrate surface and secrete toxins, and oyster mushroom hyphae at the contaminated site are inhibited or unable to grow. During the mushroom-producing period, when the bed is overly acidified and the water content is relatively low, Penicillium sometimes infects weak-growing fruiting bodies and causes diseased mushrooms to show yellow blight or rot symptoms.

(3) Causes: At the optimum temperature of 28~30°C, Penicillium conidia germinate and grow within 1~2d and quickly form new conidia. Low water content of the culture medium, an acidic pH reaction, and weak growth vigor of oyster mushroom hyphae, etc., are favorable to the growth of Penicillium.

(4) Control measures: Refer to integrated pest and disease management measures for oyster mushroom spawn and oyster mushroom cultivation; strengthen early contaminant inspection of spawn to prevent it from being concealed by oyster mushroom hyphae and becoming a hidden danger; if local contamination occurs during the spawn-running culture stage of the bags, inject 1% ketomyl solution with 5% formaldehyde solution for control; cultivation beds should be regularly sprayed with lime water or plant ash water clear liquid so that the oyster mushroom hyphae in the bed maintain relatively vigorous vitality, and Penicillium generally will not contaminate them or will cause very little harm.