Methiozolin [5-(2,6-difluorobenzyl)oxymethyl-5-methyl-3,3(3-methylthiophen-2-yl)-1,2-isoxazoline], a new annual bluegrass (Poa annua L.) herbicide for turfgrasses.

Background: Selective control of annual bluegrass (Poa annual L.) has been difficult in turfgrasses. The potential of methiozolin in this area was investigated.

Results: Methiozolin was safe on established zoysiagrass (Zoysia japonica Steud.), creeping bentgrass (Agrostis palustris Huds.), Kentucky bluegrass (Poa pratensis L.), and perennial ryegrass (Lolium perenne L.) at 1000 g ha(-1) , and controlled annual bluegrass with GR50 values of 23, 52, 104, and 218 g ha(-1) at PRE, two-, four- and eight-leaf stage, respectively, in the greenhouse. When applied at early flowering, methiozolin suppressed >80% of annual bluegrass seed heads at 2000 g ha(-1) . (14) C-Methiozolin was readily absorbed by both leaves and roots, but translocation was mainly acropetal. No herbicidal activity resulted from application to the leaf only; however, application to the soil surface only showed equivalent herbicidal activity to that of broadcast application to the leaf and soil. Methiozolin at 500 to 1000 g ha(-1) provided 80 to 100% control of annual bluegrass when applied in the fall with acceptable and temporary injury to creeping bentgrass, and about 60% control when applied in the spring with no bentgrass injury in the field.

Conclusion: Methiozolin is an excellent candidate for annual bluegrass management in turfgrasses.