Lately, we have seen quite a few collard and cabbage samples in the clinic. This season, white mold has been quite prevalent in both home gardens and commercial fields. White mold is caused by the soil-borne fungus Sclerotinia sclerotiorum. This disease is favored by cool, wet conditions and most infections occur in late winter to early spring. Early symptoms of the disease are tan, water-soaked, circular areas on the leaves or crown. These areas quickly become covered in fluffy white fungal growth, followed by a watery breakdown of infected tissue. Eventually, the fungus completely colonizes the head and produces large, black, seed-like structures called sclerotia.
|White mold (Photo: E. Lookabaugh)|
|Germinated sclerotia with mushroom-like apothecia (Photo: H.D. Shew)|
|Sclerotinia on field grown broccoli (Photo: B. Shew)|
For information on Sclerotinia-caused diseases of other hosts, see our previous blog post.
For information on another disease of collards, see our post on black rot.