Two acaricides were evaluated for cyclamen mite efficacy as a renovation treatment on ‘Totem’ strawberries at the Vancouver REU (Fig. 1). The traditional recommendation for cyclamen mite control in PNW strawberries is at the dormant and prebloom periods. The spring application(s) for cyclamen mite control is confronted with the physical problem of dense canopy growth that will reduce effective penetration of a miticide into the crowns where the adult females overwinter (Fig. 2). Past research indicate the optimum period to apply a contact miticide for cyclamen mite is when the population has migrated into the fall maturing crown inflorescences. The ideal timing is soon after field renovation after harvest in July and early August. Treatments were applied on 26 August to preselected 3 year-old ‘Totem’ plants with a Solo® backpack pressure sprayer at 40 psi with a 5500 adjustable conejet nozzle. The trial consisted of two rates of Acaramite® (biphenazate), Thiodan (endosulfan) and untreated check. The treatments were replicated six times with 2-3 crowns per treatment removed and placed in a Berlese-Tullgren funneled for controlled heat extraction into 70% ethanol.
Compared with the untreated check, Acramite 50WS and Thiodan 50WP were significantly different at 3 and 8 days posttreatment (Table 1). Contact knockdown of Acramite generally occurs within 3-4 days for cyclamen mite. This, compared with the 1-2 day knockdown by the organic-chlorine compound Thiodan. Residual persistence for both acaricides is longer than 14 days, about the average length of the cyclamen mite’s life cycle. EPA fast tracked Acramite last year as a reduced risk miticide and an OP alternative. Acramite was registered on strawberries for spider mite control at 0.75-1.0 lbs (AI)/acre in early 2002. We are working with Crompton Uniroyal Chemical for the addition of cyclamen mite control on their federal label.
|Means within columns followed by the same letter are not significantly different (Tukey test, P<0.05).|