Managing Fusarium Issues in Echeveria

Posted by Brian Sparks|March 7, 2023

Photo: Jean Williams-Woodward, University of Georgia

Often when individual plants start dying on greenhouse benches, common root pathogens, including Pythium and Phytophthora, are suspected. However, when the University of Georgia’s Jean Williams-Woodward examined echeveria stems and roots during a recent greenhouse visit, symptoms were not typical of Pythium infection, which usually causes more of a soft rot of the crown and roots. The leaves and stem had more of a dry rot appearance where the leaves yellowed, turned brown to black, shriveled, were leathery, and stayed intact.

Beneath the plant canopy on stem at the soil line, white clusters of Fusarium spores and hyphae could be seen. Fusarium spores are somewhat sticky and are easily spread by water-splashing, wind, and worker activity on contaminated tools and hands. Fusarium is a good colonizer of weakened tissues, particularly from drought stress. Soils that go through repeated cycles of excessive drying and re-wetting will stress the roots and foliage, which can be readily infected by Fusarium. The species of Fusarium was not determined on this plant sample. Most often the cause of the stem rot is Fusarium oxysporum. Some F. oxysporum isolates are very host specific; however, many are not.

In a post on e-Gro, Williams-Woodward notes that Fusarium spores and hyphae can survive on contaminated tools, benches, pots, trays, and in soil. Therefore, removal of infected plants and following good sanitation practices to reduce survival are important to reduce continued infection and spread.

“It is important to accurately identify the cause of plant diseases,” she says. “Misidentification can result in application of ineffective chemical and biological control options. Fungicides to reduce Fusarium infection are mostly ineffective on Pythium root rot, and none are effective on bacterial soft rot.”