mix sulfur with dormant oil?
The Kim Porknoy article quote Renquist as saying they can be mixed, but that is contraindicated on the Horticultural Oil (Natural Guard) and Sulfur (Bonide) instructions. The person at Garden Fever in Portland that I asked had not heard that they could be combined.
Multnomah County Oregon
It is best not to mix oil and sulfur on plant material including dormant woody plants. This is a carry over from the days of lime sulfur and oil causing harm to dormant woody plants. Despite the fact that horticultural oil, a lighter oil than dormant oil, and sulfur (not lime sulfur) are not as caustic to plant surfaces, it is a good idea to make separate sprays about tens days apart. Homeowner sized containers of lime sulfur can not be sold to the public anymore because of potential to cause harm to the applicators eyes.
Then this recommendation should be taken out of the article by Kim Porknoy on your website!
The article you are referencing must be a few years old since homeowners haven't had access to lime sulfur since late 2017 or early 2018. This article should be deleted. Where are you seeing this? My website in Douglas County doesn't have that posted. Appreciate your feedback.
I found the article posted on the OSU statewide site and sent the updates to the author of the article to change. This article was written in early 2018 and needed to be updated to current formulations and regulations. Thanks for sending me the alert. I will follow up with the author to make sure of the changes.
that's great especially since she was quoting you!