Lycopersicon esculentum Miller POTATO APHID ...

2 downloads 0 Views 139KB Size Report
significant control compared to untreated. The trend remained in the second week post-treatment, but PA densities were only significantly lower in the Warrior + ...
(E92) TOMATO: Lycopersicon esculentum Miller POTATO APHID CONTROL IN PROCESSING TOMATOES, 2002 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] Eileen Cullen 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, 2002, and fertilizers and herbicides were applied according to standard grower practice. All treatments, including untreated check, were assigned to 30 × 5 ft-plots in a RCB design, with three replicates per treatment. PA populations were allowed to develop naturally. Insecticides were applied 22 Jul, 2002, using an Echo Duster/Mister sprayer at a volume equivalent to 50 gpa, approximately one month pre-harvest. PA abundance was determined pre-treatment on 19 Jul, and one and two weeks following the 22 Jul treatments. 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 were separated using Fisher’s protected LSD (P ≤ 0.05). Pre-treatment PA counts indicated no significant difference in abundance between plots. One wk following treatment, all treatments except for the garlic oil + vegetable oil and Agri-50 provided significant control compared to untreated. The trend remained in the second week post-treatment, but PA densities were only significantly lower in the Warrior + Provado and Warrior + Butacide treatments relative to the untreated check. The lack of statistical significance is probably due to the natural decline in aphid populations that occurred between the first and second post treatment counts, which increased variability among samples. These results are promising in that they indicate that the chloronicotinyl pesticides may provide similar control to that of the organophosphates, and in combination with pyrethroids may provide better control of sucking insects on processing tomatoes than other alternatives to the organophosphates.

Mean proportion of aphid infested leaves Treatment /formulation

a

Rate amt product/acre

Untreated check -Dimethoate 2.67EC 1.5 pt Warrior T 1E 3.84 oz Actara 25WDG 4.0 oz Warrior T 1E + Actara 25WDG 3.84 fl oz + 4 oz Provado 1.6F 0.64 fl oz Warrior T 1E + Provado 1.6F 3.84 fl oz + 0.64 fl oz Assail 70WP + Decis 1.5EC 2.39 oz + 2.13 fl oz Assail 70WP 2.39 oz Warrior T 1E + Butacide 90WP 3.84 fl oz + 0.22 oz Garlic OS + Vegetable Oil 1.78% v/v + 1.78% v/v Agri-50 1% 0.33% v/v

Pre-treatb 19 Jul 29 Julyc 0.62a 0.59a 0.53a 0.54a 0.60a 0.61a 0.43a 0.53a 0.70a 0.61a 0.60a 0.77a

0.51b 0.02a 0.03a 0.10a 0.02a 0.06a 0.10a 0.01a 0.08a 0.04a 0.49b 0.61b

Column means followed by different letters differ significantly from untreated (P ≤ 0.05, Fisher’s Protected LSD). Data were subjected to an arcsine transformation prior to analysis; non-transformed means presented.

5 Augc 0.27b 0.07ab 0.08ab 0.04ab 0.03ab 0.04ab 0.01a 0.07ab 0.06ab 0.02a 0.24ab 0.61c