Iris disease Mustard seed fungus

[qt_east_bay]

Mustard seed fungus/Southern blight/scleortium rolfsii are all the same. The article referenced by Carole Duncan is the best. It is a nasty disease that is very persistent and that includes the Pacific Northwest. It is also known in onions here in the Willamette Valley. It doesn't persist in colder climates. Nebraska is about as far north as it will survive. It is extremely difficult to get rid of. For the average gardener, about the best one can do is to carefully dig out the soil and plant immediately when it is noticed. If you drop even one of the fruiting bodies, mustard seed looking, it will sprout and be back. Chemicals to treat it are all restricted use. PCNB or Terrachlor are nasty fungicides that can be used to treat it/retard it but not get rid of it totally. Terrachlor is very persistent in the environment and in humans is a neurotoxin. Efforts have been made to ban it but no other effective treatment has been found. In the South, it is used heavily on peanuts and cotton. I never eat anything other than organic peanut butter. It might be possible that peanut allergies are the result of the heavy usage of Terrachor. I think it is the same for grapes. They say grapes are toxic to dogs but the Salem Mid-America Garden huskies and dachshunds ate a lot of grapes that hadn't had fungicide applied and they never had any ill effect.

https://www.apsnet.org/edcenter/disandpath/fungalbasidio/pdlessons/Pages/SouthernBlight.aspx?fbclid=IwAR2L_BNNoeqeRj9iI-5awqMu_cXXqXHuGjbCrjcVJQ52SfDyHAk8zTKDnlM