Alternatives to Glyphosate for use around wheat fields Glyphosate has been one of the most widely used herbicides by home owners and farmers alike for many years. The safety of this herbicide has come under fire in recent years, most notably since a California jury awarded $289,000,000 to a school ground keeper who claimed exposure to roundup caused him to acquire cancer. Glyphosate is registered for use on wheat for the preharvest control of weeds in wheat where the grain is in at least the hard dough stage and as a harvest aid to dry down the plants. It is rarely used here for either purpose. It is occasionally used on fields and borders to keep weeds from going to seed. Growers have become interested in finding alternatives to glyphosate for killing weeds on field edges in response to current concerns. Alternative herbicides need to meet a few criteria:
1). It needs to be broad spectrum and control both broadleaf and grass weeds.
2). It needs to have no soil residual activity because many of these fields are going back into produce and other sensitive crops.
3). It should not be volatile and capable of moving into the field and capable of contaminating the grain.
The are some classes of herbicides that meet this criteria:
The contact PPO Inhibitors. These include Aim, ET, Gramoxone and others. These have little soil activity, are not volatile and are broad spectrum. The main problem with these is that they become weak on larger weeds. Contact Acids . These include Suppress ( Capric acid), Scythe (Pelargonic acid) and others. These are broad spectrum contacts that are approved for organic fields in some cases. Again, these are weak on larger weeds. Glufosinate( Rely, Liberty) is another contact but instead of rupturing cells on contact this herbicide inhibits a necessary plant enzyme. It is not volatile, does not have residual soil activity and can kill larger weeds at the highest rates.

To contact Barry Tickes go to: btickes@ag.arizona.edu.

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.