Difficult to control weeds – whether due to herbicide resistance or cut rates or too tall weed height/maturity or all of the above – must be taken very seriously and moved to the top of your agronomy to-do list.
Effective weed management should be planned out for each field and each crop, over multiple years in order rotate modes/sites of action (see “Create a weed management strategy ”). And a successful program begins with learning your main problem weeds and the issues that each present (see “Find your resistant weeds ”).
As you can see by the 2013 Iowa Farm & Rural Life poll, only 52% of farmers surveyed have changed their weed management program due to resistant weeds in the last 5 years. The hopeful news is that 81% of farmers applied more than one application, but digging further into the data only 71% use multiple modes of action each season, and only 60% use multiple modes in each application. While those numbers seem high, they make university weed specialists and agronomists nervous across the Midwest, especially when they know how fast glyphosate-resistant marestail, waterhemp and Palmer pigweed can infiltrate acres and cause major expense.
In fact, University of Wisconsin researcher Vince Davis estimates herbicide-resistant weeds cost U.S. farmers $2,000,000,000 annually.
A problem this large and costly has now brought together private industry, universities from across the country and farmer-led organizations to provide farmers with answers. Ag retailers/agronomists/crop consultants can also be part of the solution, because you can see by the poll, only 45% of these Iowa farmers develop their own herbicide program and 65% hire some custom application, so improved communications and education at this level needs to improve.
To help fight this loss, the soy checkoff recently created the Take Action program to help farmers implement production practices on their farms that can manage herbicide-resistant weeds. Universities and herbicide providers have joined the effort, and all are promoting a unified approach to weed management.
“Diversification is the most important thing farmers can do to manage these weeds,” says Davis. “This includes diversification of effective herbicide modes of action, diversified weed-management practices and also utilizing non-herbicide control options such as judicious tillage, cleaning equipment for weed seed and diversified crop rotations. Weeds develop resistance more quickly when production systems remain static.”
Take Action recently launched a website, www.TakeActionOnWeeds.com  (under the technical direction of Bill Johnson, weed scientist, Purdue University), with interactive guides and other information on how to diversify weed management. (See the 12-page insert in our March issue that examines the Top 11 biggest resistant weed threats). Other program supporters with United Soybean Board include Cotton Incorporated, the National Association of Wheat Growers, the National Corn Growers Association, the United Sorghum Checkoff, BASF, Bayer, DuPont, Dow, Monsanto, Syngenta and universities throughout the U.S.
So, begin now to develop your two to five-year weed management plans for each field. And seek help as needed before resistant weeds cut your margins.