Post Emergence Control of Crabgrass at the Two and Three Tiller Growth Stage

Dr. T. L. Watschke and J. A. Borger at Penn State, 1999

This study was conducted on a mature stand of perennial ryegrass at the Landscape Management Research Center, Penn State University. The objective was to evaluate the efficacy of post emergence herbicides, alone or in combination with MACRO-SORB^® foliar, for the control of smooth crabgrass. All the treatments were applied on July 19 and the control of smooth crabgrass was rated on August 23, 1999.

Treatment Description	Form	Rate	% Control
Control	-	-	0
Drive + MSO	75DF + L	0.75 lbs ai/A + 1% v/v	82
Drive + MSO + M-S foliar	75DF + L + L	0.75 lbs ai/A + 1% v/v + 2 oz/M	87
Acclaim Extra	0.57EW	0.12 lbs ai/A	80
Acclaim Extra + M-S foliar	0.57EW + L	0.12 lbs ai/A + 2 oz/M	88
Acclaim Extra	0.57EW	0.09 lbs ai/A	78
Acclaim Extra + M-S foliar	0.57EW + L	0.09 lbs ai/A + 2 oz/M	83

Results and Conclusions

Commercially acceptable post emergence control (≥85%) of smooth crabgrass was obtained only when MACRO-SORB^® foliar was added to Acclaim Extra at 0.12 lbs ai/A and to the treatment consisting of Drive at 0.75 lbs ai/A plus MSO at 1% v/v. Acclaim Extra at 0.09 lbs ai/A alone or in combination with MACRO-SORB^® foliar did not result in commercially acceptable control. However, MACRO-SORB^® foliar increased the crabgrass control rate by 5% as compared to Acclaim Extra at 0.09 lbs ai/A alone.

Control of smooth crabgrass with herbicides in combination with MACRO-SORB^® foliar