Field evaluation of Metarhizium anisopliae for control of greyback canegrub (Dermolepida albohirtum) in north Queensland sugarcane

Metarhizium anisopliae strain FI1045 consistently reduced numbers of greyback canegrub when the product was applied to rows of recently planted sugarcane immediately before filling the drill with soil. Application rates as low as 5 g product/m of row gave significant reductions, although 50 g/m was generally needed to reduce grub numbers by 70% or more, which is comparable with the currently registered insecticide. In two trials, an increase in yield of the plant crop of sugarcane of almost 50% was recorded for the high rate of FI1045, compared to the low rate or to untreated sugarcane. The two higher rates of FI1045 produced satisfactory ratoons in one of the trials, whereas other treatments in that trial ratooned poorly due to grub damage in the plant crop. Strain FI147 was generally ineffective at controlling greyback canegrub in all trials.