Tolerance of Bentgrass to Dates and Frequency of Preemergence Herbicide Treatments1
- B. J. Johnson2
Creeping bentgrass (Agrostis palustris Huds.) use for golf greens is rapidly expanding in the South where heat and drought stress is higher for this species. To maintain a good quality weed-free turfgrass, herbicides are often necessary. The purpose of this research was to determine the tolerance of ‘Penncross’ creeping bentgrass greens to herbicides applied on different dates and at different frequencies. Herbicides were applied in a randomized complete-block design to artificial rootzone greens at two separate locations. Applications of oxadiazon [3-[2,4-dichloro-5-(l-methylethoxpy)henyl]-5-(l,l-dimethylethyl)-1,3,4-oxadiazol-2-(3-one}], bensulide [O,Obis(l-methylethyl)S-[2-[(phenylsulfonyl)aminojethyl]phosphoro-dithioate] plus oxadiazon, and benefin [N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine] plus oxadiazon caused slight to moderate bentgrass shoot discoloration, but the grass fully recovered with no stand loss during the year of treatment. In general, herbicides applied in early March did not discolor bentgrass as much as they did when applied in early April. There was no advantage in bentgrass tolerance with split applications at reduced rates when compared to a full single rate. In several instances, discoloration was higher from split applications (March and May or April and June) at reduced rates for oxadiazon and benefin plus oxadiazon than when the chemicals were applied as a single full rate (March or April). These studies show that oxadiazon alone or in combination with either bensulide or benefin can be used on Penncross creeping bentgrass if some foliage discoloration can be tolerated. Some injury may occur regardless of location and time of year.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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