Invasive buttercup treatment that won't hurt bees

Asked May 22, 2020, 4:07 PM EDT

What is your recommendation to try to irradicate invasive buttercup without hurting bees? I have a 1 acre pasture area I graze goats on (Multnomah County east of Gresham), that is being invaded by buttercup. Buttercup is poisonous to livestock animals. I'm thinking of either spot application of sprayed crossbow or applying a granular broadleaf herbicide/fertilyzer. Sadly, my neighbor has a pasture full of buttercup. I recently bought two bee hives just before I realized how extensive the buttercup invasion is becoming. Next year I will take measures to try to address the buttercup when the hives are inactive - assuming they survive. I haven't seen bees around the buttercup. Is it because they don't like buttercup or because they have other food they like better? Thank you for your time, Kristi

Multnomah County Oregon

1 Response

Thanks for you question and regard for the bees.

This publication from 1996 has information about mechanical control of buttercup. https://ir.library.oregonstate.edu/downloads/t148fh57w?locale=en

A newer resource from King County, Washington has information on cultural, manual, and chemical control. https://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification...

The PNW handbook has a list of three herbicides to use in controlling creeping buttercup, make sure that pasture use is on the label and look for bee protection information. https://pnwhandbooks.org/weed/problem-weeds/buttercup-creeping-ranunculus-repens

The information below is from Shelby Filey, the pasture specialist in Southern Oregon.

The herbicide, MCPA, is effective against buttercup. But will not cause permanent damage to clovers. The following information comes from the PNW Weed Management Handbook:

MCPA LV ester or MCPA amine

Rate 1.5 lb ae/A

Time Apply when the buttercup is growing well.

Remarks Avoid drift to sensitive crops and desirable vegetation.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acidMCPA does not kill grasses or clovers, but could injure other broadleaves (flowers, shrubs, etc.) you may want to protect. Pasture grasses and clovers will be okay.

According to the Extension Toxicology Network MCPA is not toxic to bees. http://pmep.cce.cornell.edu/profiles/extoxnet/haloxyfop-methylparathion/mcpa-ext.html