News

MU weed scientist confirms six-mode resistant waterhemp

A Missouri farmer found waterhemp resistant to 2,4-D in his field and it turned out to be resistant to a half-dozen modes of action. University of Missouri Weed scientist Dr. Kevin Bradley tells Brownfield Ag News, “Through several years of field and greenhouse and lab work we were able to confirm that this particular population is resistant to six different classes of herbicides.”

Before this Missouri discovery, waterhemp had only displayed resistance to 2,4-D in Illinois and Nebraska.

Bradley says it helped that the farmer and his retailer worked together, “They knew it was glyphosate resistant as well which is not a big surprise anymore for any of us but 2,4-D is the think that sparked the phone call and the whole investigation because that is pretty rare.”

Bradley says it’s the first discovery of six-way herbicide resistance** in Missouri or anywhere in the U.S.  Bradley says the farmer immediately switched to the Liberty Link Extend system and it hasn’t recurred but it could.

Bradley says the take-home message from this is growers shouldn’t be dependent on post-emergence herbicides ONLY and should always use multiple modes of action and rotate herbicides.  **(2,4-D, atrazine, chlorimuron, fomesafen, glyphosate, and mesotrione)

AUDIO: Interview with Kevin Bradley ~