Symptom Identification and Control Methods of Penicillium Disease in Lingzhi (Reishi Mushroom)
Penicillium disease occurs commonly in edible mushroom cultivation and is an important disease on the mushroom beds of lingzhi (reishi mushroom) and other edible fungi, and it also frequently occurs during the fruiting body formation stage.
Symptoms: at harvest time, the lingzhi roots left on the cultivation bed are easily infected, and after infection they gradually infect healthy tissues near the diseased tissue. It generally invades from the base of the stipe of healthy lingzhi, after which yellow-brown rot develops and spreads upward from the base. It affects the yield and edible value of the fruiting bodies.
Pathogen: this disease is a fungal disease, Penicilliun sp., belonging to the Deuteromycotina. The conidiophores branch in a broom-like form, and the tip of the sterigma of the outermost layer of conidia is pointed and slender, in the shape of a phialide, on which conidia are borne in chains. The conidia are nearly round, colorless, single-celled, about 3 microns in diameter, and can only be seen clearly under a high-power microscope at 400x. When growing on potato sucrose agar medium, the early mycelium is white, slender, and lies flat on the surface of the substrate, appearing slightly powdery; when a large number of conidia are formed, the color of the colony gradually changes from white to green or blue.
Disease characteristics: this pathogen is a weakly parasitic fungus that lives on various organic matter. After forming large numbers of conidia, it can spread through airflow, and when temperature and humidity are suitable, it will produce mycelium on organic matter. This pathogen prefers acidic conditions, and acidic compost and conditions with relatively low moisture content are favorable for its growth and spread. During the lingzhi fruiting period, when the moisture content of the compost is relatively low, the relative humidity of the air is too low, the young lingzhi grows weakly, and the lingzhi roots remaining on the bed are not removed in time, the disease is favored to occur.
Control methods
(1) After harvest, clean the cultivation site in time, remove the weak young lingzhi and the remaining lingzhi roots, and reduce the occurrence of the pathogen.
(2) Strengthen cultivation management. During the stages of lingzhi bud and lingzhi cap formation, spray water on the floor of the cultivation room to keep it moist, and ventilate in a timely manner.
(3) Reasonably adjust the pH of the compost and keep the medium at a neutral to weakly alkaline reaction, which can inhibit the mycelial growth of this pathogen. Lime can be used to adjust the pH of the compost; 1% lime can be added when mixing the substrate, and after picking the first flush of mushrooms, spray once with 2% lime water clear liquid 1 time.
(4) Chemical control: after the disease occurs, spray 25% carbendazim at 1:500 or 70% thiophanate-methyl at 1:800 on the mushroom bed.
Commonly used agents: carbendazim, thiophanate-methyl.