Effect of dazomet on annual bluegrass emergence and creeping bentgrass establishment in turf maintained as a golf course fairway

Dazomet (tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione) is a soil fumigant labeled for turfgrass renovation. Little is known about dazomet efficacy on annual bluegrass (Poa annua L.) seedling emergence, particularly when it is surface-applied. The objectives of this field study were to determine (i) the effects of rate and plastic covering of surface-applied dazomet on annual bluegrass seedling emergence in turf; and (ii) effective creeping bentgrass seeding intervals following surface applications of dazomet. All treatments were applied to established turf during late summer in 2000 and 2001. Covering dazomet treatments with plastic sheets resulted in fewer annual bluegrass seedlings than in noncovered treatments. All plastic-covered dazomet treatments (388, 340, 291, and 194 kg ha^-1) provided greater than 98% reduction in annual bluegrass seedlings when compared with the plastic-covered controls during 2000 and 2001. When not covered with plastic, the 388 kg ha^-1 dazomet treatment provided 97% fewer annual bluegrass seedlings in 2000 and 92% fewer seedlings in 2001 than the noncovered controls. Results of the seeding interval experiment revealed that creeping bentgrass (Agrostis stolonifera L.) groundcover and yields were not inhibited when seeded 3 d after a surface application of dazomet at 388 kg ha^-1.