THE POTENTIAL FOR THE REMOVAL OF ORGANO - PHOSPHATE INSECTICIDES FROM STONE-FRUIT PRODUCTION IN THE GOULBURN VALLEY, AUSTRALIA

Victoria's Goulburn Valley produces 25% of Australia's stone-fruit crop, of which 60% are peaches grown for the processing (canning) industry. Organo-phosphate (OP) insecticides have traditionally been used to control the primary pests: Oriental fruit moth (OFM) (Grapholita molesta Busck., Lep: Tortricidae), and light brown apple moth (LBAM) (Epiphyas postvittana Walker., Lep: Tortricidae). Since 1995, industry surveys have recorded a declining trend in the effectiveness of OP sprays with the average damage levels from both pests in canning peach crops being typically 1–7%. In comparison, areas treated with pheromone based mating disruption (MD) for OFM have reduced average damage levels to 0.1%–0.2%. It is well known, however, that MD is less effective when the population density of pests is very high. Therefore, application of OP sprays have been necessary to treat these areas to reduce pest population and minimize subsequent OFM damage. The prolonged over-use of OP sprays is considered disruptive to integrated pest management (IPM) systems.

An effective method for reducing OFM population densities to levels below the economic threshold is the adoption of Wide Area Mating Disruption (WAMD). This strategy involves treating an entire fruit production area with MD including all stone and pome fruit trees, where MD is not normally used. The WAMD project covering about 800 ha was established in the Cobram region in the 1997/98 season. This area was large enough to minimize any edge effects and migration of mated OFM females. Preliminary results of monitoring more than 230 OFM traps and damage assessments showed that the WAMD approach worked effectively.

To reduce the use of OP sprays for LBAM and other pests it is possible to substitute with biological methods, such as application of Bacillus thuringiensis and Trichogramma carverae.