AVERMECTIN B-1, ISAZOFOS, AND FENAMIPHOS FOR CONTROL OF HOPLOLAIMUS-GALEATUS AND TYLENCHORHYNCHUS-DUBIUS INFESTING POA-ANNUA

Avermectin B-1, isazofos, and fenamiphos were evaluated in greenhouse experiments for efficacy against two common turfgrass parasites, Hoplo laimus galeatus and Tylenchorhynchus dubius. Treatments in all experim ents were arranged in a completely randomized design and replicated fo ur times. In the first experiment, avermectin B-1 at rates of 0.2 and 0.4 kg a.i./ha and isazofos at rates of 2.3 and 23 kg a.i./ha signific antly reduced populations of both species of parasitic nematodes compa red to controls at 14 and 28 days after treatment (P less than or equa l to 0.01). In the second experiment, the greatest reductions in both nematode populations occurred at 28 and 56 days after treatment, where 23 kg a.i./ha of isazofos was applied (P less than or equal to 0.01). These reductions, however, were not different from reductions of H. g aleatus at 28 and 56 days after treatment (P less than or equal to 0.0 1) or T. dubius at 56 days after treatment (P less than or equal to 0. 01), where 0.2- and 0.4-kg a.i./ha rates of avermectin B-1 were mixed throughout the soil. In the third experiment, the greatest population reduction of H. galeatus was observed with a 0.4-kg a.i./ha treatment of avermectin B-1 at 56 days after treatment (P less than or equal to 0.05). T. dubius populations were reduced by the 0.4-kg a.i./ha rate o f avermectin B-1 at 28 (P less than or equal to 0.01), 56 (P less than or equal to 0.05), and 70 (P less than or equal to 0.01) days after t reatment. In the fourth and fifth experiments, avermectin B-1 at rates of 7.5 and 15.2 kg a.i./ha consistently reduced nematode populations compared to controls and performed as well or better than fenamiphos ( P less than or equal to 0.01).