INSECTICIDE GRANULE DEPOSITION IN TURFGRASS

The distribution of granular pesticides, used to control insects in tu rfgrass, may influence the pesticide hazard to birds foraging for food ; however, there is little information on the exposure of birds to gra nules applied to turfgrass. Granules were spread onto golf course gree ns [creeping bentgrass (Agrostis palustris 'Penncross')], fairways [pe rennial ryegrass (Lolium perenne) and annual bluegrass (Pea annual], a nd roughs [Kentucky bluegrass (Pea pratensis)]. Granule height in the grass profile was measured and granules visible from above were counte d. Within one hour after application, granules in the rough were less visible (15%) than those in the fairway (38%) or on the green (67%). I rrigation (4 mm) decreased the percentage of granules visible from abo ve to 7% for the rough, 20% for the fairway, and 46% for the green. Af ter irrigation, granules in the rough were higher (mean height 9 mm) a bove the soil surface than were granules applied to fairways (6 mm) an d greens (4 mm). The most likely place for waterfowl to be exposed to granular insecticides is on the fairway, where the birds' habit of gra zing to a height of 10 to 20 mm would expose them to I to 15% of the a pplied granules if they feed soon after an irrigation following granul e application.