Bulb Blue Mold – Penicillium bulb mold – Penicillium hirsutum – Penicillium tulipae

Bulb blue mold Common name Bulb blue mold Penicillium bulb mold Causal agent Bulb blue mold is a fungal disease caused by various penicillium species. The fungi mostly attack injured bulbs or those that are already weakened by another disease. Scientific name Penicillium hirsutum Penicillium tulipae Symptoms & Signs Bulb blue mold disease first appears as brown spots on the bulb. The brown spots develop into a blue moldy growth that extends to basal roots and scales. It causes discoloration and stunted growth of the leaves as well as malformation of the bulbs. Depending on the plant, the tulip bulbs turn hard and dry, while the lily bulbs become soft and mushy. Transmission Penicillium is a soil fungus that enters healthy bulbs through openings such as wounds and damaged tissues. The fungi produce spores that may travel to other healthy plants by means of wind, water, or insects. High humidity between the temperatures of 70 F to 77 F favors the spread of disease. Time of concern Early spring to late summer Common hosts Tulips Lily Daffodils