Poision hemlock seeds.

Asked February 2, 2019, 11:20 AM EST

I have an old manure pile that has poison hemlock seeds in it. I have kept the ones that have germinated on the surface removed. Places I have used the manure for mulch or fertilizer last summer have spouted plants now. It is a large pile and I intended to put it out on my pasture and hay fields this spring. My first guestion is how long can they survive deep in the pile? I am struggling a bit getting it under control on my 80 acres as it is I don’t want to spread it around again. It is a culmination of multiple piles the previous owner left around the barnyard and much came out of the barns and should be ok. If its seeds survive for a lond period of time any suggestions how to safely utilize this manure?

Multnomah County Oregon

1 Response

Thank you for your question. Since the seeds remain viable for 2-3 years, keeping them and the manure aeay from animals, as this explains: https://extension.oregonstate.edu/pests-diseases/weeds/poison-hemlock-western-water-hemlock-deadly-plants-may-be-growing-your-pasture ‘Hot’ composting, where the temperature of the manure reaches 145 to165 deg., will kill most seeds. You can cover the piles with black plastic, and our summer heat will drive it to that temperature. Here is an article about manure and weed seeds generally: https://clackswcd-wpengine.netdna-ssl.com/wp-content/uploads/weeds.pdf Hope this is helpful. Good luck!