Role of Endothall in the Control of Annual Bluegrass in Turf

Abstract

Endothall (7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid) was evaluated for controlling annual bluegrass(Poa annuaL.) infestations in Kentucky bluegrass(Poa pratensisL.) and creeping bentgrass(Agrostis stoloniferaL.) turfs. Growth of annual bluegrass was selectively suppressed by three applications of 0.6 kg/ha of endothall, two or three applications of 1.1 and 2.2 kg/ha, and one application of 4.5 kg/ha made to the single plant sand cultures. Field treatments were variable and seasonably dependent. Endothall selectively killed annual bluegrass when applied to roots in sand culture at a concentration of 2.7 × 10−4molar. A granular formulation of endothall provided selective control of annual bluegrass in field and greenhouse studies. High watering frequency prior to application, low organic matter content of the underlying soil, and predominance of the annual biotype of annual bluegrass enhanced the selective action at the lowest rates of endothall application.