Browsing by Author "Kettle, CG"

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Control of greyback canegrub by manipulating adult behaviour : SRDC final report BSS205
(BSES, 2000) Logan, DP; Kettle, CG; Horsfield, A; Cocco, RF
In the Burdekin, early-planted and early-cut cane is more frequently damaged by greyback canegrub than other classes of cane. Cane height is important in attracting egg-laying greyback beetles and early-planted and early-cut cane is generally the tallest cane on Burdekin farms during the period of beetle flight. In this project, the effect of trap crops (tallest sections of cane or other crops) on damage to surrounding cane was determined. These trap crops were created by planting cane 'early', harvesting sections of blocks in early harvest rounds, planting forage sorghum, applying high rates of N fertiliser, and selective irrigation. In the 1999- and 2000-harvest seasons, early-plant and early-harvest or ratoon trap crops reduced grub numbers in adjacent blocks by 70-100%. The single critical factor for successful trap crops was the height of the crop relative to adjacent blocks. Cane cultivar and fertiliser rate were not important in the success of trap crops. Beetle flight determined by light-trap catches in the summers of 1998-1999 and 1999-2000 generally had a single identifiable peak. Dispersal of greyback beetles was difficult to quantify.
Key factors in control of Greyback Canegrub populations : SRDC final report BS120S
(BSES, 1998) Robertson, LN; Dall, DJ; Lai-Fook, J; Kettle, CG; Bakker, P
Greyback canegrub outbreaks with severe losses in sugar production have persisted for more than six years in the Burdekin district, but population densities of the pest have declined at locations in the Herbert Valley, Tully and Innisfail districts over the same period. Six species of pathogenic organism were found to cause disease and death of greyback canegrubs, with relatively high incidence in grubs collected from the Herbert Valley, Tully and Innisfail study sites, but low incidence in the Burdekin. No deaths from entomopathogenic diseases were recorded in 226 grubs examined from the Burdekin in 1998. Two microorganisms, Adelina sp (Protozoa: Coccidia), and Metarhizium anisopliae (Deuteromycetes fungi), were the most prevalent pathogens in far north Queensland grub populations. Incidence of Adelina sp. alone accounted for 55-64 % of the variance in mortality of grubs recorded from samples collected across all locations in 1994 and 1995. The initial objectives of this SRDC funded study were to study dispersion of greyback canegrubs in the soil profile and devise a sampling program to estimate population density with known precision; monitor population density of greyback adults, eggs and larvae; identify mortality factors which act on each life stage including climate, natural enemies and farming practices; determine key factors which control greyback population changes and suggest ways to suppress population growth; develop model which predicts changes in greyback populations. Following a review in April 1995 the project was expanded to encompass the following additional objectives; assess the effects of crop management strategies on frequency of occurrence of diseases in greyback canegrubs; demonstrate pathogenicity of selected microorganisms to greyback grubs; determine dose/response relationships (ie infectious dose, time to death, effects on larval feeding and growth); attempt small-scale in vitro culture of selected microorganisms which display pathogenicity to grubs.