APPLICATION OF PRODIAMINE TO IMMATURE TURFS

Turf managers use prodiamine to control annual grasses in mature turfs . Earlier, evaluations of prodiamine have indicated it has an elevated soil persistence and high activity on susceptible species. This persi stence raises concern for prodiamine's effect on juvenile turf. An exp eriment was established to evaluate the effect of prodiamine on juveni le Kentucky bluegrass turf. Significant loss of quality occurred on tu rf less than one year old receiving a single application of prodiamine at greater-than-or-equal-to 1.4 kg/ha. Split applications of prodiami ne did not significantly decrease turf quality. Prodiamine at 0.8 and 2.2 kg ai/ha and DCPA at 23.5 kg ai/ha, applied in the fall the previo us three years, significantly reduced the number of overseeded Kentuck y bluegrass seedlings two years after planting. In a subsequent study, prodiamine at greater-than-or-equal-to 0.8 kg/ha and DCPA at 23.5 kg/ ha applied once the previous fall significantly reduced the number of overseeded Kentucky bluegrass seedlings 56 d after planting. An analys is of prodiamine rate versus seedling density was found to be signific antly correlated (r2 = 0.79). Nomenclature: DCPA, dimethyl 2,3,5,6-tet rachloro-1,4-benzenedicarboxylate; prodiamine, 4-dinitro-6-(trifluorom ethyl)-m-phenylenediamine); Kentucky bluegrass, Poa pratensis L. #3 PO APR, 'Aspen,' 'Trenton,' 'Rugby,' 'Parade,' 'Glade.'