Relampago Blight Disease Caused by the Fungus Parvodontia relampaga: PP393, 9/2026

Abstract

Starting in 2019 in northern and central Florida, a thread blight caused by a previously undescribed fungus was observed with increasing frequency, affecting both hardwood and conifer hosts with a higher prevalence in wet, shaded environments. This emerging disease, called relampago blight, is caused by the fungus Parvodontia relampaga and is characterized by its distinct white, lightning-shaped rhizomorphs (fungal cords) that grow on the stems and branches of affected host plants. When the fungus fully develops, it can also grow on the undersides of plant leaves, causing dieback of leaves and small branches. This fungus has been found on a wide array of host plants and detected in 31 counties throughout Florida.