Boron Tolerance in Four Turfgrass Species.

Borax (sodium tetraborate) can be used as a herbicide for broadleaf weed control for howe lawns because of higher B sensitivity in dicotyledons than monocotyledons. However, it may cause damage in monocotyledons, including turfgrasses at high concentrations. Five turfgrasses, Kentucky bluegrass mixuture, Kentucky bluegrass mono stand, tall fescue, buffalograss, and blue grama were exposed to 5 levels of borax (0, 10, 20, 30, and 40 oz product/1,000 sq. ft) and kept in a greenhouse for 7 weeks to determine B sensitivity. An interaction between turfgrass and borax application was observed. All grasses showed a similar level of tissue B content at low concentrations (averaged = 227 and 480 ppm for 0 and 10 oz, respectively). At higher concentrations (≥ 20 oz), tall fescue had the highest amount of B tissue accumulation, followed by Kentucky bluegrass and blue grama, buffalograss showed the least B tissue content. Turf quality was not affected by borax at lower concentrations (≤ 10 oz). Tall fescue treated at the highest concentration (40 oz) showed acceptable quality (≥ 6) 5 weeks after the treatment (WAT). Kentucky bluegrass treated at 30 oz was able to recover by 7 WAT. In contrast, blue grama and buffalograss showed unacceptable quality when borax was applied higher than 20 and 30 oz product/1,000 sq. ft, respectively. Tissue dry weight was increased occasionally in borax treated tall fescue and Kentucky bluegrass, but not in buffalograss or blue grama. Our results showed that B sensitivity varied in turfgrass species and B sensitivity may not be related to tissue B content.