(E93) TOMATO: Lycopersicon esculentum Miller POTATO APHID CONTROL IN PROCESSING TOMATOES, 2003 Frank Zalom Department of Entomology University of California, Davis One Shields Ave Davis, CA 95616-8584 Phone: (530) 752-3687 Fax: (530) 752-1537 E-mail:
[email protected] Patricia Thompson Corin Pease Nikki Nicola Potato aphid (PA): Macrosiphum euphorbiae (Thomas) Insecticide efficacy trials for potato aphid were conducted in field plots at the University of California, Davis Vegetable Crops Farm. Processing tomatoes were seeded on 60-inch beds in early Apr 2003, and fertilizers and herbicides were applied according to standard grower practice. All treatments, including the untreated check, were assigned to 30 × 5 ft-plots in a RCB design, with three replicates per treatment and six replicates for the untreated check. Because of low PA populations in the field, each plot was inoculated with 10 heavily infested tomato leaves on 9 Jul, from a nearby processing tomato field in Woodland, Yolo County, CA. Fulfill and Platinum treatments, only, were applied 12 Jul, 2003, and all other treatments were applied on 1 Aug. All treatments but Platinum were applied using an Echo Duster/Mister sprayer at a volume equivalent to 50 gpa. Platinum was applied directly to the soil in 12.8 oz of water at the base of each plant using a Hudson pump sprayer, and plots were furrow irrigated later the same day. PA abundance was determined pre-treatment on 29 Jul, and 4, 11, and 18 days following the 1 Aug application. Aphid sampling consisted of removing 30 leaves below the highest open flower on plants throughout each replicate plot. To obtain the proportion of aphid-infested leaves per replicate, the number of leaves with one or more aphids was divided by 30. Data were subjected to ANOVA and means from the untreated check using a t-test (P ≤ 0.05). Pre-treatment PA density averaged 22% infested leaves on 29 Jul, and no significant difference in abundance between plots. This average was slightly below the treatment threshold level of 25 - 50% infested leaves, and PA densities in the untreated check remained relatively stable throughout the experiment. Fulfill, Platinum alone, and Activol did not provide significant control relative to the untreated check on any of the sampling dates. Although not significant, PA densities in the Fulfill treatment plots were noticeably reduced as sampling progressed. Dibrom provided significant control on the first sampling date only, while Knack + Danitol provided control by the last two sampling periods. All other treatments provided significant control relative to the untreated check throughout the experiment. These data support our observations from the previous year that foliar applied chloronicotinyl insecticides and many pyrethroid insecticides can give equivalent control to the organophosphate insecticide dimethoate. The pyrethroids, Warrior and Mustang Max, the chloronicotinyls, Actara and Assail, and the pyrethroid and chloronicotinyl combinations all provided excellent control. More work is needed with
timing and possibly application methods for Platinum, Fulfill and Knack in order to optimize their effect on PA control in tomatoes. Mean proportion infested leaves Treatment /formulation
Rate amt product/acre
Untreated check -Dibrom 8E 1 pt a 2.75 oz Fulfill 50WDG Activol OS 3% v/v Warrior 1CS 3.84 fl oz Actara 25WDG 4 oz Warrior 1CS + Actara 25WDG 3.84 fl oz + 4 oz Platinum 2SCa 8 oz a 3.84 fl oz + 8 fl oz Warrior 1CS + Platinum 2SC MustangMax 0.8EC 0.018 lb (AI) MustangMax 0.8EC 0.025 lb (AI) F1785 50DF 0.054 lb (AI) F1785 50DF 0.071 lb (AI) MustangMax 0.8EC + F1785 50DF 0.025 lb (AI) + 0.071 lb (AI) Assail 70WP 2.39 oz Warrior 1CS + Assail 70WP 3.84 fl oz + 2.39 oz Dimethoate 2.67EC 1.5 pt Lannate 90SP + Danitol 2.4EC 0.9 lb (AI) + 0.2 lb (AI) Knack 0.86EC + Danitol 2.4EC 0.054 lb (AI) + 0.2 lb (AI)
5 Aug 0.23 0.10* 0.18 0.20 0.03* 0.04* 0.02* 0.25 0.01* 0.03* 0.09* 0.07* 0.05* 0.01* 0.02* 0.01* 0.00* 0.00* 0.11
12 Aug 19 Aug 0.23 0.09 0.11 0.31 0.01* 0.00* 0.01* 0.19 0.00* 0.02* 0.08 0.00* 0.01* 0.01* 0.06* 0.00* 0.01* 0.03* 0.04*
0.16 0.13 0.08 0.16 0.00* 0.02* 0.00* 0.19 0.00* 0.02* 0.03* 0.02* 0.01* 0.00* 0.02* 0.01* 0.01* 0.03* 0.02*
*Means are significantly different from the untreated check (P ≤ 0.05, t-test). Data were subjected to an arcsine transformation prior to analysis; non-transformed means presented. a Application date 12 Jul; all other treatments applied 1 Aug, 2003.
