Nomoto, R. M.

Van Steenwyk, Robert A.

Undetermined

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4. Chemical Control/ New ProductsCONTROL OF CODLING MOTH BYCOMBINATION PROGRAMS OF IGRANDORGANOPHOSPHATE INSECTICIDES IN WALNUTSR. A. Van Steenwyk & R. M. NomotoDepartment ofEnvironmental Science, ( |̂A ^Policy and Management ^'f^ d^]A/r"University ofCalifornia, Berkeley, CA 94720 ifaffiMethods and Materials - A study was conducted in a commercial 'Payne' walnut orchardplanted on a24 ft. x24 ft. spacing (75 tree/acre) in Hollister, California. Fourteen treatmentswere replicated three times in a randomized, complete block design. Each replicate was anindividual tree. Foliar sprays were applied with a handgun operating at 200 psi with a finishedspray volume of250 gal/acre (3.33 gal/tree). Applications were scheduled basedon degreedays /K(DD1. DP were calculated with abiofix of 20 April for the first generation and with abionx of22 July from the second generation. Flight activity ofcodlingmoth (CM) was monitored with apheromone" trap placed high uTthe tree canopy. Control of the first CM generation(overwintering flight) was evaluated by inspectingall dropped nuts weeklyfrom 10 July throughl4AugustforCM infestation. Control ofthe^econd generation (summer flight) was evaluated atcommtnSTiarvest on 14 September by inspecting amaximumof 250 nuts per tree for CM andnavel orangeworm (NOW) infestation.Results and Discussion:First Generation Evaluation - The study was conducted in a semi-abandoned orchard that hadexperienced very high CM damage in previous years. One edge (along a road) of the orchardharbored alarge population ofground squirrels which removed most ofthe nuts from the adjacentreplicate. Due to the low number of nuts in this replicate, it was deleted from the study.Because ofalack ofproper maintenance, the number ofnuts per tree was generally low and therewas considerable variation inthe number ofnuts among experimental trees. Since it was possibleto count all the nuts per tree at harvest, we calculated the percent CM infested dropped nuts bydividing the total CM infested dropped nuts by the total nuts at harvest plus the total CMinfested dropped nuts. This removed the effect ofa variable crop load on the number of CMinfested dropped nuts by transforming the data to a percent infested dropped nuts.All experimental treatments had significantly lower percent CM infested dropped nutsthan the untreated control. There was no significant difference in the percent CM infesteddropped nuts between the experimental treatments and the grower standard treatment.Harvest Evaluation- All experimental treatments had significantly lower percent CM andNOW infested nuts at harvest than the untreated control. When considering CM and NOWinfestation separately, there was no significant difference between the experimental treatmentsand the grower standard. However, when CM and NOW infestations were combined, twoapplications ofEsteem with Volck oil followed by one application ofConfirm with Volck oil andthree applications of the low rate of Success with Volck oil had significantly higher percentinfestations than the grower standard.450*4^Conclusions:This study was conducted against an extremely high CM population with over 45% ofthe nuts infested. Since walnuts are not a preferred host of CM, it is uncommon to observeinfestation greater than about 25% in walnuts. Considering the size of the CM population, thecontrol achieved by most experimental treatments was acceptable, if not outstanding.Particularly impressive were: three applications of Brigade, Confirm with Volck oil followed bytwo applications ofConfirm, Dimilin and Volck oil and Esteem with Volck oil followed by twoapplications ofConfirm, Dimilin and Volck oil.Mean Percent CM Infested Dropped Nuts for First Generation and CM and NOW Infestation atHarvest at Hollister, Calif. -1998.Ratelb(AI)/acNo.Appl.DroppedNutsMean* Percent InfestedNuts at harvestTreatment* NOW CM Total1) Lorsban4E 2.0 1 1.8 abc 0.3 ab 3.7 abed 4.0 abedImidan70W** 4.0 1Lorsban 4E 2.0 12) Lorsban 75WG 2.0 1 1.8 abc 0.0 a 4.8 abed 4.8 abedImidan70W** 4.0 1Lorsban 4WG 2.0 13) Brigade 10WP 0.08 3 0.8 ab 0.5 ab 1.9 ab 2.4 abc4) Comply 40WP*** 0.1 2 1.2 abc 0.0 a 4.1 abed 4.1 abedSuccess 2SC*** 0.141 15) Esteem 2.9EC*** 0.113 2 3.9 be 0.0 a 5.8 bed 5.8 bedeSuccess 2SC*** 0.141 16) Esteem2.9EC*** 0.113 2 3.2 be l.Oab 11.4d 12.4 eConfirm 2F*** 0.25 17) Esteem 2.9EC*** 0.113 2 3.3 be 0.9 ab ll.Od 11.9deConfirm 2F 0.25 1+ Latron CS-7 by vol. 0.125%8) Confirm 2F*** 0.25 1 0.4 a 0.0 a 1.0 a 1.0 aConfirm 2F*** 0.25 2+Dimilin25W 0.59) Esteem 2.9EC*** 0.113 1 2.4 abc 0.0 a 2.0 abc 2.0 abConfirm 2F*** 0.25 2+Dimilin25W 0.510) Success2SC*** 0.094 3 4.6 c l.Oab 11.8 d 12.8 e11) Success2SC*** 0.141 3 3.5 be l.Oab 8.2 bed 9.2 cde12) NAF-443 37.6WP*** 0.094 3 1.4 abc 1.6 b 8.9 cd 10.5 de13) NAF-443 37.6WP*** 0.141 3 2.7 abc 0.3 ab 4.7 abed 5.0 abed14) Untreated — 0 14.1 d 5.4 c 45.7 e 51.1 fMeans followed by the same letter within a column are not significantly different (Fisher'sprotected LSD, P < 0.05). Data analyzed usingan arcsin transformation.**pH of Imidan applications was adjused to about 6 pHby Bu-pH-er.***Treatment contained 1.0%) Volckoil by volume.k(>

Control of codling moth by combination programs of IGR and organophosphate insecticides in walnuts

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Control of codling moth by combination programs of IGR and organophosphate insecticides in walnuts

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