Expanded registration for Metarhizium strains against canegrubs : SRDC final project report BSS246

Abstract

Eight fungicides and three liquid insecticides are registered in Queensland for application to sugarcane at planting, and these may come into contact with Metarhizium during application from cane planters. Seven of the chemicals were tested for deleterious effects on two Metarhizium isolates, FI-147 and FI-1045 (BioCane?), in laboratory and field experiments.In growth studies on medium, the fungicides Cane Strike? and Sportak? were about 10 times more toxic than Shirtan? and Tilt?, while toxicity of the latter fungicides was about 100 times that of the three insecticides Lorsban?, Talstar? and Regent? (based on active ingredient). When the amount of active ingredient in each product and field application rates are considered, the expected order of harmfulness in commercial use would be Regent < Talstar < Lorsban < Cane Strike < Tilt < Shirtan < Sportak.In a field experiment where Metarhizium granules were sprayed with each chemical (except Regent) at very high rates and then covered with soil, only Shirtan showed any toxic effect on spore viability, with a reduction from 82% to 69%. No harmful effect of any chemical was detected in counts of colony-forming units in soil samples or in bioassays of treated soil using negatoria and greyback canegrubs. No reduction was found in viability of FI-1045 on nine farms, where BioCane granules were applied though commercial planters with fungicide, compared with granules buried in untreated soil. Thus, we believe that BioCane is compatible with these chemicals in practice, and a label change for BioCane to include application at planting has been drafted with Bio-Care Technology Pty Ltd.