Verticillium nonalfalfae

[3] Colonies of Verticillium nonalfalfae on Potato Dextrose Agar (PDA) reach 3.5-5.5 cm in diameter after two weeks, initially white, later darkening due to the formation of submerged resting mycelium.

[3] Aerial mycelium is abundant, cottony to powdery, composed of smooth-walled hyphae 1.5-3 μm wide.

Resting mycelium is present, consisting of brown-pigmented, thick-walled hyphae, up to 9 μm wide, often aggregated and sometimes torulose.

[1][4] Verticillium nonalfalfae has a wide host range including hops, kiwifruit, spinach, solanaceous plants like eggplants and potatoes, and tree of heaven (A. altissima).

One important host of V. nonalfalfae is hops, with infections found both in the United States and most places around the world.

[7] The symptoms of hosts infected by V. nonalfalfae on hops are categorized into two pathotypes: mild and lethal.

For the lethal pathotype of V. nonalfalfae on hops, hosts suffer from rapid weakening that ultimately leads to death.

[citation needed] Long-distance transportation of conidia involves insects such as ambrosia beetles, which are thought to be critical in creating regional outbreaks of wilting in Ailanthus.

Common hop plants showing foliar symptoms of Verticillium wilt caused by Verticillium albo-atrum on a field at Oregon, USA.
Common hop plants showing foliar symptoms of Verticillium wilt caused by Verticillium albo-atrum on a field at Oregon, USA.
Joanne Rebbeck, a Research Scientist and Timothy Fox, a Biological Research Technician, both from the USDA Forest Service Northern Research Station, inoculate Ailanthus trees with Verticillium nonalfalfae to evaluate its effectiveness as a biological control. (Photo courtesy of USDA Forest Service, Wayne National Forest)