Pesticidal Impact on Leafminers and Parasites in Celery, 1982

‘Tall Utah 52-70 R’ celery was transplanted 5 Aug. at the Univ. of California South Coast Field Stn. in Santa Ana, Calif. The crop was sprinkle irrigated for 3 weeks and drip irrigated thereafter. Experimental plots were three beds wide (40-in centers) by 50 ft long with one untreated buffer row between plots. Each bed contained two rows of plants 6 to 8 in apart. Treatments were replicated four times in a randomized complete block design. Insecticides were applied weekly with a tractor mounted boom sprayer from 19 Aug. to 28 Oct. As plant height increased, nozzles varied from 1 to 3 per row and carrier (H2O) increased from 50 to 100 gal/acre. Hollow cone nozzles incorporated D3 orifice disks, #25 cores and 50-mesh screens. All treatments except MK-936 contained 0.04% spreader-sticker (Leaf Act 40). Beet armyworm damage was based on number of damaged plants found in 50 randomly selected plants per replicate from the center bed at harvest. Leafminer pupae were collected weekly from four pupal trays (4 by 8 in) per replicate and inserted between rows. Number of dead parasites were also counted. At harvest the number of mined leaves per plant for 4 plants per replicate was recorded as an index of leafminer activity.