California Agriculture

As concerns increase over changes in pesticide regulations, farmworker safety, surface and groundwater contamination and escalating costs and uncertainties associated with chemical controls, walnut growers need effective and cost-efficient ways to produce walnuts with minimal use of pesticides. This study compared the effectiveness of Biologically Integrated Orchard Systems (BIOS) with conventionally managed walnut orchards in the northern San Joaquin Valley from 1999 to 2001. We found no significant differences between BIOS and conventional blocks in nut quality or yields. Codling moth was effectively controlled by pheromone disruption and alternative pest-control methods. Mating disruption, by itself, appears to provide good control of codling moth in many orchards. However, it is still more expensive for growers than conventional pest-control methods.