White and yellow sweet clover are introduced weeds that have become serious problems on ditch banks and in other none crop areas where glyphosate is the only herbicide used. These weeds are tolerant to glyphosate and they proliferate when this is the only herbicide used. It is necessary to use other herbicides when you need to control sweet clover. Growth regulators (2,4-D,dicamba,MCPA,clopyralid,fliroxpyr etc.) or high rates of some of the contact herbicides, (paraquat,Sharpen,ET,etc) should be more effective. Sweet clover, (Melilotus officianalis) was introduced from Europe and Asia for bee forage, as a soil builder and stabilizer and for forage. It is now a serious problem especially on unlined ditches or ditch banks. Sweet clover seed is hard and it can last for 10 to 15 years in the soil. Fire can stimulate germination and burning ditch banks can make the problem worse. Sweet clover can grow to 6 ft in height and live through both the summer and winter. White sweet clover is more common than yellow.

Selecting for weeds?

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.