Date 26 February 1992

Title of Project Spray Application for the Greenhouse

Institution where work is being conducted University of California-Davis

Amount of Endowment Grant $ 12,000
Covering Period 1/1/92 to 12/31/92

Anticipated Date of Project Completion/Final Report 1993

Individual(s) Conducting Project:

(List Project Leader First)

Ken Giles, Agricultural Engineering - UCD - Title Assistant Professor

Telephone Number 916-752-0687

Mike Parrella, Entomology - UCD - Title Chair and Professor

Spray Application for the Greenhouse

Ken Giles and Mike Parrella

University of California-Davis

Progress Report to the American Floral Endowment, 2/26/92

A. Project Objectives:

The objectives of the project are to determine pesticide deposition and dissipation characteristics of air-atomization,

electrostatic spraying equipment and to compare the characteristics to those of conventional,

“wet” sprayers. The goal is to improve pest control efficacy and reduce the amount of pesticide used and

the accompanying human hazard in greenhouses. Further, the effectiveness of electrostatic application of

Enstar against greenhouse whitefly is being investigated.

B. Summary of Work Since Project Inception, and

C. Results to Date:

Greenhouse trials of conventional, “wet” spray and electrostatic (ESS, Inc.) applications have been

conducted at Oki Nursery in Sacramento, CA. Permethrin (formulated as PounceTM 3.2 EC) was applied

to florist chrysanthemums grown at 4 plants per 6 inch pot. Using both application techniques, Pounce

was applied at a rate of 40 oz/acre in application volumes of 5 gal/acre for the electrostatic system and

250 gal/acre for the conventional system. To study the effects of different climatic conditions,

applications were made in the summer of 1991 and the winter of 1992. Pesticide deposition and residue

on the chrysanthemum foliage was measured at 1, 3, 7 and 14 days after application. Pesticide deposition

was also measured on the bench tops, aisle ways and underneath benches.

Figure 1 shows the pesticide deposition and dissipation from each application The electrostatic sprayer

achieved approximately 4 times the deposition of the conventional sprayer. For the summer and winter

applications, breakdown of the electrostatic deposition was faster and slower, respectively than the

conventional deposition. The wet spray deposition half-life was approximately 8 days. The summer and

winter half-lives for the electrostatic application were 7 and 18 days, respectively.

Figure 2 shows the location and recovery of all applied pesticide. For the electrostatic application, 56%

of the applied pesticide reached the target foliage as compared to 16% from the wet spray application.

Most of the wet spray deposition was on the bench top surfaces.

Work is currently underway to determine efficacy of Enstar against whitefly when applied through the

electrostatic system. Initial trials have indicated that phytotoxicity may occur on blooming crops such as

gerberas.

D. Future Plans Covered by the Endowment Grant:

Future plans are to continue field studies of reduced-volume application of pesticides, particularly biorational

materials. The electrostatic sprayer system has recently been upgraded with the latest available

components.

E. Anticipated Benefits for Floral Industry:

The anticipated benefits to the floral industry are reduction in application rates of pesticide required for

efficacious pest control. Information regarding residue dissipation and reduction in greenhouse

contamination (pesticide on non-target areas) may assist in regulatory decisions regarding the equipment.

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