| Abstract | Soldier flies are a serious soil-dwelling pest of cane, and there is no insecticidal control available. In large-plot trials, numbers of soldier fly larvae in plant and first ratoon crops were lower after a long fallow, with old crops destroyed early in the harvest season and new crops planted late the following year, than after a short fallow with late crop destruction and early planting. This difference was not maintained in older ratoons in the trials, but that may not be so if long fallowing was implemented on a larger scale. Two long fallowing methods, either using herbicide to kill old crops and weeds or growing soybeans, were at least as effective as bare fallowing with frequent cultivation, the previously recommended cultural control procedure for the pest. These methods are now recommended for soldier fly management. Various other procedures were tested for killing soldier fly larvae in fallows ? rotary hoeing, application of a biocide (metam-sodium), combination of a systemic pesticide (carbofuran) with a lure crop (sorghum), and growing brassica break crops ? but these either did not control soldier flies or failed for other reasons. The annual addition of organic matter to crops as either a green-cane trash blanket or mill mud did not change the soldier fly status of fields within a crop cycle. Long fallowing by appropriate means is the best way of minimising the risk of damaging soldier fly populations in young ratoon crops, although at the cost of reduced plant crop yields due to a shortened growing period. |
