Codling moth (CM); Cydia pomonella (L.)
Pear psylla (PP); Cacopsylla pyricola Foerster
European red mite (ERM); Panonychus ulmi (Koch)
Twospotted spider mite (TSSM); Tetranychus urticae Koch

R. A. Van Steenwyk and
R. M. Nomoto

Department of E.S.P.M.
201 Wellman Hall
University of California
Berkeley, CA 94720-3112
Phone: (510) 643-5159

CODLING MOTH CONTROL IN SUISUN VALLEY PEARS, 1998: The study was conducted on mature 'Bartlett' pear trees in a commercial orchard near Fairfield, CA. Sixteen treatments were replicated four times in a RCB design. Each replicate consisted of an individual tree. Treatments were applied with a hand-held orchard sprayer operating at 200 psi and delivering 200 gpa of finished spray (2.87 gal/tree). Application timings were based on degree days (DD). DD were calculated with a 20 Apr biofix for the first generation and 11 Jul for the second generation using a single sine wave horizontal cutoff model with a lower threshold of 50°F and an upper threshold of 88°F and with air temperature data from the IMPACT weather station near Cordelia, CA. Target application timings were: Esteem with Volck oil at 100 DD followed by Success or Confirm with Volck oil at 250 and 650 DD from the 1st biofix and 250 DD from the 2nd biofix; Esteem with Volck oil at 100 DD followed by Confirm plus Dimilin plus Volck oil at 650 DD from 1st biofix and 250 DD from 2nd biofix; Guthion at 250 and 650 from the 1st biofix followed by Success or Confirm with Volck oil at 250 DD from 2nd biofix; Guthion at 250 DD followed by Confirm plus Dimilin plus Volck at 650 DD from 1st biofix and 250 DD from 2nd biofix; Guthion at 250 DD followed by Success or Confirm with Volck oil at 650 DD from 1st biofix and 250 DD from 2nd biofix; Guthion (Grower Standard) and DPX-MP062 at 250 and 650 DD from 1st biofix and 250 DD from 2nd biofix. The actual application timings were: 100 DD from the 1st biofix was applied at 100 DD on 27 Apr, 250 DD was applied at 257 DD on 15 May, 650 DD was applied at 626 DD on 16 Jun and 250 DD from the 2nd biofix was applied at 265 DD on 21 Jul. Control of the first CM generation (overwintering flight) was evaluated on 8 Jul and control of the second generation (summer flight) was evaluated at commercial harvest on 11 Aug by inspecting a maximum of 250 fruit per replicate for CM infestation. Control of motile TSSM, ERM and PP nymphs were evaluated weekly from 26 May through 27 Jul by sampling 10 exterior and 10 interior leaves/replicate. The leaves were brushed and the motile TSSM, ERM and PP nymphs were counted under magnification (20X).

This trial was conducted against a high CM population with over 50% of the fruit infested at harvest in the untreated control. All experimental treatments had significantly lower CM infestation compared to the untreated control. All experimental treatments that contained one or more applications of Guthion had higher pear psylla, twospotted spider mite and European red mite populations than those experimental treatments that did not include Guthion with the exception of DPX-MP062. No phytotoxicity was observed with any experimental treatment.