Timothy from Milton Freewater, Oregon writes
I have a large commercial iris garden and would like to control the incidence of Botrytis convoluta in new plantings. I live in the Columbia Basin of eastern Washington/Oregon, and this problem is a nuisance. Not damaging to established clumps, but can be a problem new plantings. Most of the incidences occur late winter to early spring. Problem abates by early summer. Drainage is excellent, and the field is in full sun. Soil is a volcanic based silt loam.
According to the Penn State Extension Office: "Do not plant infected rhizomes. Destroy infected plants." It would be best to reach out to your local cooperataive extension office or a local nursery who have experience with Iris diseases and a treatment regimen. We do carry a product called OHP Strike Plus 50 WDG Fungicide that's labeled to treat for Botrytis as well as Cleary 3336F Fungicide.
Answer last updated on: 03/29/2017