| Abstract/Contents: | "Tall fescue (Lolium arundinaceum) and common bermudagrass (Cynodon dactylon) are widely used in North Carolina (NC) turf areas including golf courses, home lawns, commercial properties, and athletic fields. Large crabgrass (Digitaria sanguinalis) and smooth crabgrass (Digitaria ischaemum) are two of the most troublesome weeds that homeowners and turfgrass managers must contend with when managing these turf species. These common weeds can become a major problem because of their ability to establish and reproduce quickly, especially in less dense turf stands. Field experiments were conducted during 2007 at two locations (Sandhills Research Station, Jackson Springs and Lake Wheeler Field Labs, Raleigh) to determine if turf mowing height could suppress large crabgrass in common bermudagrass and tall fescue. Additionally, trials were initiated to evaluate preemergence herbicide efficacy for large crabgrass control. Large crabgrass was seeded in each experiment in early March. Evaluated mowing heights included 0.5", 1.0", 1.5" and 2.0" for bermudagrass and 1", 2", 3" and 4" for tall fescue, which were initiated once soil temperatures reached an optimum for crabgrass emergence. In bermudagrass, no significant differences (P = 0.05) were discerned among mowing heights or locations. However, there were significant differences in tall fescue in Raleigh, with mowing heights of 1", 2", 3" and 4" resulting in 95%, 48%, 13%, and 0% crabgrass cover, respectively, by early-September. While the Jackson Springs location contained 79%, 74%, 31%, and 0% crabgrass cover, respectively, with mowing heights of 1", 2", 3" or 4". This shows that the growth habitat of tall fescue can be used to help suppress large crabgrass by implementing the correct mowing height. Evaluated herbicides included single or split applications of Barricade 65WG - prodiamine (0.75 or 0.5 fb 0.25 lb ai/a), Dimension Ultra 40WP - dithiopyr (0.5 or 0.25 fb 0.25 lb ai/a), Ronstar 2G - oxadiazon (3 or 1.5 fb 1.5 lb ai/a), Pendulum AquaCap 3.8CS - pendimethalin (3 or 1.5 fb 1.5 lb ai/a), Surflan 4FL - oryzalin (3 or 1.5 fb 1.5 lb ai/a), and Team Pro 0.86G - benefin + trifluralin (3 or 1.5 fb 1.5 lb ai/a). Visual estimates of percent large crabgrass control were collected in September. Statistics prevented pooling of data across locations. Both locations showed significant differences between the different herbicides. Split applications at the Jackson Springs location by Team Pro, Surflan, Pendulum AquaCap, Ronstar, Dimension Ultra, and Barricade resulted in 75%, 100%, 100%, 76%, 83% and 99% control large crabgrass, respectively. Single applications at the same location resulted in 85%, 99%, 99%, 85%, 93%, and 99% control large crabgrass, respectively. Regardless of split or single applications, Team Pro and Ronstar did not control large crabgrass as well as the other herbicide treatments. Split applications at the Raleigh location by the same preemergence herbicides resulted in 97%, 97%, 99%, 99%, 99%, and 99% control large crabgrass, respectively. Single applications resulted in 95%, 84%, 97%, 95%, 95%, and 100% control large crabgrass, respectively. Surflan at the Raleigh location showed a major decline in crabgrass control from split to single applications. At both locations, single applications performed equal to or better than split applications for the herbicides evaluated. Overall, the major differences occurred between the two locations, each preemergence herbicide, and between single and split applications." |
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