Although wheat is ready to harvest ,weeds can still be a problem and control measures should be considered. They can add moisture in the tank, cause contamination to the grain and add weed seeds in the field and grain. There are some herbicides that can be used but there are potential problems with all of them and they all can only be used when the grain is in at least the hard dough stage and essentially done. There are contacts, growth regulators and glyphosate that are registered as preharvest aids in wheat.

Contacts: These include Aim/Shark Sharpen and Valor) Paraquat ( Gramoxone) is not registered for this use. Sharpen is not accepted by all markets so check the label closely. Good coverage and an adjuvant are necessary and these will be weak on grasses.

Growth regulators: These include Dicamba( Clarity) and 2,4-D). These are both volatile, slow and weak on grasses. The volatility and potential injury to sensitive crops at this time of year will be a major drawback. Ally ( metsulfuron) is not a growth regulator but is systemic and registered for this purpose in some regions. It can have soil residual and may not be a good option when rotating to vegetables.

Glyphosate (Roundup): Registered for this use although contamination of the grain has become a major issue and this is not recommended for use here.

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.