Postemergent Broadleaf Weed Control in Turf with Penoxsulam Herbicide.

The development of penoxsulam; 2-(2,2-difluoroethoxy)-N-(5,8-dimethoxy(1,2,4)triazolo (1,5-c)pyrimidin-2-yl)-6-(trifluoromethyl)benzenesulfonamide, in turf was based on its unexpected high level of postemergent broadleaf weed activity when applied on a fertilizer granule carrier.  The majority of granule products presently sold in the cool-season turf retail and lawncare market segments consist of 2,4-D + MCPP-p or 2,4-D + MCPP-p + dicamba mixtures.  Atrazine based products lead in the St. Augustinegrass market segment.   The current cool-season granule products provide limited efficacy on the key driver weeds; Trifolium repens L., Taraxacum officinale Weber, Plantago lanceolata L. and Plantago major L. and require foliar moisture at application to express full activity.  Atrazine is the current standard for Hydrocotyl spp. and Stachys floridana Shuttlew control in St. Augustinegrass because of limited alternatives.  Atrazine continues to be under increased regulatory pressure limiting its use.  Field data developed from 2003 through 2007 demonstrated that penoxsulam is a highly effective alternative to current commercial granule herbicide standards both in the cool and warm-season market segments.  It has shown exceptional control of Trifolium repens L. and Hydrocotyl spp, does not require foliar moisture at the time of application and appears to enhance the activity of 2,4-D and dicamba when used in combination.  Penoxsulam is currently being developed in combination with 2,4-D and dicamba for the cool-season markets and as a stand-alone atrazine replacement for St. Augustinegrass.  Use rates in the cool-season turf will range from 17 to 23 g ai/Ha and 45 to 70 g ai/Ha in St. Augustinegrass and other warm-season turf markets. The field performance data demonstrate that penoxsulam would be an excellent alternative to MCPP-p in granule combinations and atrazine for the St. Augustinegrass market segment.