Control of Alfalfa Looper Larvae on Spring and Fall Spinach, 1974

All treatments were applied at 4.2 kg/cm2 (air pressure) and 389 L/ha through D2-13 “TEEJET” hollowcone nozzles mounted 28 cm apart on a rear-mounted boom sprayer fitted to a JD-420 tractor traveling at 4.4 km/hr. The boom height was adjusted to provide maximum coverage of the foliage as the plants grew. Each of the 4 replications of each treatment was applied to a 1.5 x 6 m, 4-row bed (35 cm interrow spacing). The insecticides were evaluated as maintenance treatments (repeated applications to control eggs and small larvae) and/or as clean-up treatments ( a single application to control large larvae, 48 hr prior to harvest). The afternoon prior to each treatment, two, 1.2 x 1.5 m sites at the ends of each bed were stocked with eggs or 2nd to 5th stage larvae from the laboratory culture to ensure populations of uniform size and stage. The spring crop was planted on March 25 and was sprinkler irrigated (2.5 cm/hr) weekly until just before the 3rd of 4 applications. Usually, the crop was irrigated 2 to 3 days prior to a given application. Temperatures ranged from 1 to 13 to 15 to 33°C during the spring test and from 11 to 28 to 4 to 22°C during the fall test. The fall crop was planted on August 1 and was sprinkler irrigated in the same way as the spring. The percentage control obtained on June 10 (spring test) and September 30 (fall test) was determined by cutting and examining the foliage and the soil beneath at each site.