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Options for Managing Mites and Weevils

Options for Managing Mites and Weevils

Lynell Tanigoshi, Bev Gerdeman and Hollis Spitler
Washington State University
Mount Vernon Northwestern Washington Research & Extension Center
Horticulture Growers’ Short Course, Abbotsford, BC, 19 February 2009

Spider Mites.  For several decades, the twospotted spider mite, Tetranychus urticae, was the only economically important spider mites species reported on caneberries and strawberries in Washington State.  By the mid-90s, we reported four species of spider mites occurring in Washington grown red raspberry:  yellow spider mite, Eotetranychus borealis carpini in 1992; European red mite, Panonychus ulmi in 1995; and the McDaniel spider mite, Tetranychus mcdanieli in 1997 (Tanigoshi et al. 2003).  Population levels of spider mites in northwestern Washington in 2008, exceeded expectations given the unseasonably cool, wet spring and early mild summer temperatures.  This in contrast to 2007 when spider mite populations were generally non-economic ones, especially in northwestern Washington.  Problematic flare-ups of the yellow spider mite (YSM), Eotetranychus carpini borealis, were particularly severe in the Northwood area of Lynden where late May populations on both ‘Meeker’ and ‘Willamette’ exceeded our provisional treatment level of 25 motile life stages per leaflet by 10 to 100-fold.  Female YSM emerge from diapause earlier and disperses earlier than the twospotted spider mite (TSSM) from mid-April to May.  This species migrates to distal primocane foliage tied along the top trellis wire of red raspberry in April to May.  Our research data has shown the YSM prefers cooler spring and fall temperatures.  The onset of warm weather combined with stressed foliage provided the right conditions for a mid-season (May to August), region-wide flare up of mostly YSM and lesser levels of the TSSM and European red mite on the distal half of the canopy bearing most of the developing flower buds.Also, interest will be focused on field monitoring of miticide trials and lab bioassays to determine current levels of tolerance to the registered pyrethroids, bifenthrin (Capture/Brigade/Discipline) and zeta-cypermethrin (Mustang).  If these two spider mite species are not controlled, defoliation in early fall will induce fruiting buds to develop prematurely, subjecting primocanes to winter injury and causing indirect economic damage.

Yellow spider mite field trial, 2008
yellow spider miteOn 8 July 2008, we field-tested 2 rates of the recently registered Acramite 50WS (bifenazate) and Acramite 4SC and experimental Envidor 2SC (spirodiclofen) with Vendex™ (fenbutatin-oxide) on a mature ‘Meeker’ site in Lynden, WA.  Envidor is a Group 23 acaricide.  Treatments were replicated five times and plots measure 30 feet long by 10 feet wide.  Twenty-five leaflets were taken at random from primocanes at chest height from both sides of the row.  These samples were processed with a mite brushing machine.  Compared with the untreated check, empirically all miticides performed comparably to each other and all were significantly different from the untreated check out to 44 DAT (Table 1, only 14 DAT shown)

Table 1.  Yellow spider mite control on red raspberry, Lynden, WA, 2008
Motile YSM/leaflet
Treatment lb(AI)/acre Ptrm 3DAT 6DAT 10DAT 14DAT
Acramite 50WS 0.37 8.2a 0.2b 0.2b 0 0.1b
Acramite 50WS 0.5 12.5a 0.6b 0.4b 0 0.4b
Acramite 4SC 0.5 10.5a 0.7b 0.2b 0 0.1b
Envidor 2SC 0.28 9.5a 0.6b 0.2b 0.1b 0.2b
Vendex 50WP 1 9.8a 0.4b 0.4b 0 0.2b
Untreated check 10.6a 8.6a 5.8a 1.8a 3.5a
Mean within columns followed by the same letter are not significantly different
(Fisher’s protected LSD, P<0.05), PRC ANOVA SAS.

Mixed spider mite field trial, 2008
spider miteA postharvest population of TSSMand YSM were sampled and treated on 25 September 2008 in a 3 year-old ‘Meeker’ field at the WSU Mt. Vernon NWREC.  Pretreatment densities for these late season infestations approximated 10-13 motile life stages/leaflet.  Though non-economic, these numerically increasing populations and cool/cloudy weather conditions were ideal to compare formulations of Acramite 50WP and Acramite 4SC with experimental IGR Envidor 2SC on an established TSSM and incipient YSM infestation.  Rates and application methods were identical to those used for YSM above.  A silicone surfactant (0.5% v/v) and Volck supreme oil (1% v/v) was included with Acramite and Envidor, respectively.  The method and applications were applied as reported above for the Lynden red raspberry trials.  Compared with the untreated check, Acramite 50WP provided 6-fold reduction-suppression of motile spider mites at 13 days posttreatment (Table 2).  This compared with an average comparable to the untreated check at 13 DAT.  This result was significantly different from these treatments at the Lynden site in mid-summer for YSM.

Table 2.  Mixed spider mite species control on red raspberry, Mount Vernon, WA, 2008
Treatment lb(AI)/acre Ptrm 4DAT 7DAT 13DAT
Acramite 50WS 0.5 10.4a 0.9b 6.3a 4.6b
Acramite 4SC 0.5 12.8a 3.3b 9.5a 23.5a
Envidor 2SC 0.28 13.2a 3.1b 7.0a 14.3ab
Untreated check 11.9a 9.5a 14.3a 27.7a
Means within columns followed by the same letter are not significantly different
(Fisher’s protected LSD, P<0.05), PRC ANOVA SAS.

Root Weevils.  The Otiorhynchus complex of the black vine weevil, O. sulcatus, clay-colored weevil, O. singularis, strawberry root weevil, O. ovatus, and rough strawberry root weevil, O. rugosostriatus remain ranked as Washington’s small fruit growers key arthropod pests.  Bifenthrin remains the industry’s insecticide/miticide of choice for a post bloom, foliar ‘clean-up’ application for adult root weevils, worms and other insect contaminants.  The supplemental label for Capture and Brigade’s registration recommends a post harvest or pre-bloom drench application at the crown of plants for raspberry crown borer control.  This tactic will also provide excellent control of overwintering, early season emerging clay-colored, rough strawberry root weevils (Tanigoshi and Bergen 2002) and western raspberry fruitworm.  We will report on recent field trials testing two new mode of action insecticides that show promise as drench or foliar applied weevilcides on canefruit and strawberry.

black vine weevilBlack vine weevil field trial, 2008.  Sprench treatments of two experimental insecticides were compared with three registered weevilcides and an untreated check in a 3 year-old ‘Totem’ planting in Burlington, WA.  Each treatment was applied to five replicates separated by 5’ buffers and arranged in a randomized complete block.  A single row separated each block and blocks were composed of three, 30’ row plots.  Treatments consisted of chlorotraniliprole (DPX-E2745 1.67 lb/gal SC, 0.09 lb(AI)/acre); metaflumizone (BAS 320 I, 0.178 and 0.25 lb(AI)/acre + Penetrator Plus 0.25% v/v); thiamethoxam (Actara™, 0.047 lb(AI)/acre); bifenthrin (Discipline™, 0.1 lb(AI)/acre; zeta-cypermethrin (Mustang™, 0.05 lb(AI)/acre and an untreated check.  The treatments were applied between 9:30 to 10:30 pm on 16 July 2008, with a tractor- mounted plot sprayer equipped with three Spray Systems™ row application units.  Each unit was equipped with 3 twin fan spray tips (TJ60-8006) mounted on a row boom to deliver 150 gal/acre at 45 psi at 1.8 mph.  Black vine weevil (BVW) density per plot was determined from 3 minute, timed counts of adult weevils on strawberry foliage after 10 pm with the aid of flashlights at 1, 5 and 9 days posttreatment.

field trialsBoth rates of metaflumizone performed comparably and there was no significant difference in adult BVW mortality with our standard bifenthrin at 5 to 9 days posttreatment (Table 3).  At 5 DAT, the strawberry rows in each metaflumizone plot were littered with BVW adults in a state of relaxed paralysis.  All were lying on their backs with weak leg and mouthpart movements.  These symptoms fit those described by BASF for their sodium channel blocker insecticide, with death delayed 1-72 hours after ingestion.  Although chlorotraniliprole’s mode of action is very different from that of metaflumizone, affected insects exhibit very similar symptoms including paralysis, cessation of feeding and ultimately death.  Pending their registrations, these data indicate both new chemistries could be rotated with registered weevilcides, thus ensuring their long-term use and sustainability in small fruit IPM program

Table 3.  Mean black vine weevils per three minute search, 2008.

Mean adult BVW





















BAS 320 I





BAS 320 I










Untreated check  




Mean within columns followed by the same letter are not significantly different (Fisher’s protected LSD, P<0.05), PRC ANOVA SAS.

aphidRecent registrations of insecticides and miticides and pending ones with differing modes of action and entry will facilitate the long sought for chemistries to integrate pests and resistance management systems for root weevils, leafrollers and aphids while promoting biological control of spider mites in red raspberry and strawberry by the phytoseiid mite predator,Neosieulus fallacis.

Tanigoshi, L. K. and J. R. Bergen.  2002.  Managing root weevils in Washington State Red Raspberries.  Acta Hort. 586: 309-314.

Tanigoshi, L. K., T. A. Murray and B. S. Gerdeman.  2003.  Spider mites on red raspberry.  WSU Ext. Bull. 1959E.