Terbacil (3-tert-butyl-5-chloro-6-methyluracil) was applied to highbush blueberry plants (Vaccinium corymbosum L. ‘Pemberton’, ‘Rancocas', ‘Jersey’, and ‘Concord’) growing in a Rifle peat, Camas clay loam, or Mossy Rock silt loam for control of quackgrass [Agropyron repens (L.) Beauv.]. Control was 80 to 100% from applications made in April after the blueberry plants broke dormancy. Higher dosages proved phytotoxic from these applications on Camas clay loam. Applications in February or March while the blueberry plants were still dormant caused no phytotoxicit; to the blueberry plants and provided 80 to 90% quackgrass control. Four consecutive yearly applications caused no residual buildup to the point of phytotoxicity to blueberry plants. Carry-over of terbacil in the soil from year to year did occur.
