Postemergence Tropical Signalgrass Control.

With the loss of MSMA in the state of Florida Tropical Signalgrass (Urochloa distachya) is becoming an even hard to control weed issue. Therefore in the Spring of 2013 several studies were initiated in South Florida to evaluate various herbicide and herbicide combinations for the control of Tropical Signalgrass. Herbicides used in the study 1 included Tribute Total, Xonerate, Dismiss, Sencor, and Drive XLR8. These herbicides were applied alone and in combination with one another. Treatments were initiated on March 4, 2013 with a sequential treatment applied two weeks after the initial. These plots were set-up as a split plot design where one half of the plots received two applications of Specticle at 5 oz/A. Specticle was applied on March 4, 2013 and again 6 weeks later. In Study 2 a different approach was evaluated where we looked at spot treatments made two, three, four and five times with Tribute Total at 0.073 oz/gal + methylated seed oil (MSO) at 0.5 % V/V + Ammonium sulfate at 1.5 lb/A. Spot treatments were made on a two week interval beginning March 4, 2013. Best results from study 1 were seen with a combination of Tribute Total + Xonerate and Tribute Total + Xonerate + Dismiss. Results from the spot treatment study indicate that a minimum of 3 spot treatment applications of Tribute Total are need to effectively control Tropical Signalgrass. Future research will include evaluating fall applications of various herbicides and combinations of for improved long term Tropical Signalgrass control.