Modifying the location and application rate of insecticides for carrot rust fly (Psila rosae F.) control in New Zealand

Carrot rust fly damage levels at different distances from the crop edge int o the carrot field were studied. Overall root damage was up to 40% at crop edge, but was 0-5% at 30 m into the field. Application of phorate granules at reduced-rate only around the edges of carrot fields (10 m-strip), contro lled larval damage effectively, requiring approximately 10% of the recommen ded rate (i.e. 0.22 kg a.i./ha) (i.e. the mid-field remaining untreated).