USE OF INSECTICIDES AND A PRESS WHEEL TO CONTROL SOIL INSECTS AFFECTING SORGHUM AND SUNFLOWER ESTABLISHMENT IN SOUTHERN QUEENSLAND

Abstract

AbstractField trials at 5 sites in southern Queensland were used to determine the effectiveness of soil compaction with a press wheel and various methods of application of 4 insecticides for the control of soil insect pests of sorghum and sunflower seeds and seedlings. The pests involved were black field earwigs, Nala lividipes (Dufour), sugarcane wireworms, Agrypnus variabilis (Candèze), seedharvesting ants (Pheidole sp. and an unidentified species), and false wireworms, Pterohelaeus alternatus Pascoe, P. darlingensis Carter, Gonocephalum macleayi (Blackburn), Cestrinus trivialis Erichson.Some of the techniques of insecticide application improved establishment at 4 of the sites. Heptachlor was the most effective insecticide overall and caused no phytotoxicity to either crop. Chlorpyrifos and terbufos had apparent phytotoxic effects in some trials. Carbaryl which was applied only by water injection, was less effective than heptachlor and (sometimes) chlorpyrifos.Where insecticides caused no apparent phytotoxicity, applications by seed dressing, presoaking, water injection, and in‐furrow spray generally were equally effective in improving establishment. Seed dressing and presoaking required less active ingredient and were the most efficient ways of applying insecticide.Soil compaction with a press wheel also significantly increased establishment, at all sites for sunflower and at 4 sites for sorghum. Response to compaction by the press wheel at 2 sites was attributed solely to insect control as soil water was adequate and control plots had extensive insect damage and low emergence.