Tuesday, November 14, 2006

Foliar and Root Absorption and translocation of bispyribac-sodium in cool-season turfgrass.

Darren Lycan and Stephen Hart. Rutgers, The State University of New Jersey, Department of Plant Biology and Pathology, 59 Dudley Road, New Brunswick, NJ 08816

Response of creeping bentgrass, annual bluegrass, and Kentucky bluegrass to foliar, soil, or foliar plus soil applications of bispyribac-sodium was evaluated in greenhouse studies.  Soil-only and foliar plus soil applications of bispyribac at 148 or 296 g ai/ha resulted in greater injury and shoot dry weight reductions of all species 28 days after treatment (DAT) compared to foliar-only treatments.  Creeping bentgrass was less injured than annual or Kentucky bluegrass regardless of application placement.  Further studies evaluated foliar and root absorption and subsequent translocation of 14C-bispyribac-sodium in creeping bentgrass, annual bluegrass, Kentucky bluegrass, and roughtstalk bluegrass.  Foliar absorption into creeping bentgrass was less than that of other species at most harvest timings from 4 to 72 hours after treatment.  Annual and roughstalk bluegrass translocated greater levels of foliar-absorbed 14C to the crown and shoots compared to creeping bentgrass.  Annual and roughstalk bluegrass accumulated approximately 47% more 14C per dry weight of plant tissue than creeping bentgrass and 74% more than Kentucky bluegrass after 72 hours in nutrient solution containing 14C-bispyribac.  Annual and roughstalk bluegrass translocated approximately 80% of root-absorbed 14C to shoots; whereas creeping bentgrass and Kentucky bluegrass translocated less (66% of absorbed for both species).  These studies suggest that bispyribac is readily absorbed by roots and translocated to shoots which may contribute to its total activity within a plant.  In addition, creeping bentgrass displayed lower levels of foliar and root absorption and subsequent translocation than annual and roughstalk bluegrass which may contribute to greater bispyribac tolerance displayed by creeping bentgrass.