Poison Oak in compost delivered by local composting company

Asked July 22, 2017, 11:20 PM EDT

I had garden mulch delivered and I got poison oak from spreading the mulch in my garden beds.. I contacted the company and their representative said he had never heard of that and dismissed my claim. I am still getting poison oak outbreaks by working out in the yard. I use Tecnu when I get it. The mulch was hot when it was delivered. My question's are - Do you have any information on this subject? I - Can the compost be tested for urushiol?

Clackamas County Oregon

3 Responses

Thank you for your question. (1) Here is a link to a CDC article with information about exactly how poison oak (and poison ivy and poison sumac) causes problems for humans, and a second link explaining the offending oil, plant parts and how they relate to composting. (2) Here is an OSU resource for testing the compost to see if it does, indeed, contain the oils.

I hope these are helpful. Good luck!

Thanks for your help. As with my web search, the links you provided do not confirm that the urushiol oil is potent or less potent after composting. (Sounds like a fun student research project :)

Also the link for testing the compost to see if it does, indeed, contain the oils says you cannot have compost tested that has poison oak in it.

Any other ideas?

I'm afraid I don't. I've had lots of training in composting (both as a Master Gardener and a Master Recycler), but I have come across no studies on the ability of the composting mechanisms (heat and microbes) to break down urushiol oil. High heat, as in a woodland fire situation, makes the problem worse, as described in this OSU article.

While we know that bacteria are the mechanism that cleans up oil in the Gulf, I can find no studies of any soilborne bacterium that destroys urushoil oil. In fact, in the one article that even puts the words "urushoil oil" and "microbes" together, there is some evidence that the oil is anti-microbial! But, this resource indicates there is a fungus that kills poison ivy.

I think I've exhausted my research skills for now, but if I come across something, I'll send you another post. Unless you find some student who wants to research it in the interim!