Arthropod Control and Chemical Phytotoxicity on Strawberries, 1985

Abstract

Abstract ‘Parker’ strawberries were transplanted 2 Nov ’84 into drip-irrigated, double-row raised beds. Beds were mulched with clear plastic approximately 1 wk following transplanting. Treatments were arranged in a randomized complete block design with 4 replicates of each treatment. Each replicate consisted of 2 sub-beds (17 plants/sub-bed). Insecticides were applied on 29 Mar, 11 and 25 Apr, 9 and 23 May, and 6 and 20 Jun. As foliage height and density increased, nozzles varied from 2-4/row and carrier was 100 gal/acre. Disc-type nozzles incorporated D-2 or D-3 orifice discs, #23 cones, and 50 mesh screens. All treatments included 0.04% spreader-sticker (Leaf Act 80A). Spider mite population evaluation was based on percentage of plants infested on the highest trifoliate on each plant for 10 plants/replicate every wk (40/treatment/wk). Data were collected every other wk from 25 Mar-17 Jun, and again on 25 Jun. Aphid counts were collected at the same time as the spider mite data, but percentage of plants infested was based on the presence or absence of aphids on the oldest trifoliate. Again, 10 randomly selected plants were sampled/replicate every other week. Phytotoxicity was assessed by photosynthesis (PH) and stomatal conductance (RS) measurements made with the LI-COR 6000 on 10, 15 and 26 Apr (13 days after 1st treatment, 4 days after the 2nd treatment, and 1 day after the 3rd treatment, respectively). Yield data were collected (all berries in each replicate) on the same dates as the mite counts.