First report of Myrothecium roridum causing leaf spot on garden hydrangea in the United States.
Garden hydrangea (Hydrangea macrophylla) is a popular flowering shrub that grows well in Tennessee (USA) but foliar diseases impact their appearance, health, and market value. Leaves of garden hydrangea showed necrotic lesions with concentric rings of brown and dark brown at the Tennessee State University Research Centre in McMinnville. A fungus was recovered from June and July leaf samples with 20% frequency of isolation from approximately 40 leaf pieces that were surfaced sterilized and plated in potato dextrose agar. The fungus isolates were identified as H. macrophylla based on morphological characteristics, molecular investigations and pathogenicity tests. This is thought to be the first report of M. roridum causing leaf spot on H. macrophylla in the United States.