Flurprimidol Effect on the Emergence and Growth of Annual Bluegrass and Creeping Bentgrass
- J. E. Haley and
- T. W. Fermanian *
Annual bluegrass [Pou annua (L.)) and creeping bentgrass (Agrostis palustris Huds.) are major components of golf course turf. The application of the growth regulating compound flurprimidol [α-(methylethyl)- α-[4-trifluoromethoxy)phenyl]-5-pyrimidinemethanol] might interfere with the emergence and early growth of creeping bentgrass used in overseeding programs, or cause sudden reductions in either species population. Greenhouse experiments were conducted in the summer and winter of 1985 to determine the effects of flurprimidol on germinating seeds and young seedlings of annual bluegrass [P. annua ssp. annua (L.) Timm.] and creeping bentgrass (A. palustis Huds. ‘Penneagle’). Seeds of each species were sown in pots filled with sterilized Flanigan silt loam (fine, montmorillonitic, mesic Aquic Argiudolls) soil. Flurprimidol (0.6, 0.8, 1.1, and 2.3 kg ai. ha−1) was applied preemergence or postemergence to plants 3 to 6 cm in height. Verdure collected 6 wk following treatment showed a significant decrease in yield (25 to 94% of the weight of untreated seedlings) of seedlings of both species treated with flurprimidol prior to or after emergence regardless of rate. Correlation between verdure and flurprimidol rate were significant (0.51 to 0.71) for both species and application timings in both experiments. Injury to both species observed 6 wk following treatment was similar based on visual estimates of color with severe injury (>6) occurring at rates greater than 1.1 kg a.i. ha−1 in the summer experiment. Similar injury was observed in the winter experiment for both species when flurprimidol was applied postemergent. While the effect of flurprimidol at tested application rates was prominent, similar results have yet to be verified through field testing. Thus, turfgrass managers are cautioned to be aware of potential adverse effects of flurprimidol to creeping bentgrass when overseeding.
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