Resource Information

Postharvest Control of Thrips with Pyrethroids on Dendrobium, 1993  

By: T. Y. Hata, A. H. Hara and Ben K.S. Hu

Beaumont Agri. Res. Center, University of Hawaii-Manoa, 461 W. Lanikaula St., Hilo, Hawaii 96720, Phone (808) 935-2885

HOST: Dendrobium Orchid: Dendrobium 'Uniwai Princess'
TARGETED PESTS: Frankliniella occidentalis (Pergande), Western flower thrips; Thrips palmi (Karny), Melon Thrips

Postharvest insecticidal treatments were evaluated from Jun through Jul 1993 at the University of Hawaii, Waiakea Experiment Station in Hilo, HI. Flowers used in this study were randomly harvested from a commercial dendrobium farm in Kailua-Kona, HI. Dendrobium plants were well established growing in 0.5 inch crushed basalt rock under 30% polypropylene shade using standard cultural practices. Treatments consisted of 4 replicates with 5 inflorescences per replicate. In study 1, inflorescences were dipped floral end first into 5 gal buckets containing the insecticide solutions (25.7oC). Inflorescence were submerged for 3 minutes, and gently agitated 10 times at emergence, at 1.5 minutes and again before removal for a total of 30 times. Control flowers were dipped in water following the same procedure as described. After dipping, inflorescences were held in buckets and allowed to air dry. In study 2, the double insecticidal dip of Mavrik Aquaflow consisted of immersing inflorescences (27.3oC) as described above, followed by a 2 h waiting period and a second 3 min insecticide immersion. A 2.5 cubic meter chamber was used to fumigate inflorescence with floragas (2 h exposure at 31.5oC). Control flowers for the floragas were held in an identical untreated chamber. Twenty-four hours after treatment, blossoms were removed from the inflorescence, counted, and placed in Berlese funnels heated with a 60 watt incandescent light bulb. Thrips were collected in a 8:2:1:1 solution of ethanol, distilled H2O, acetic acid and glycerin and the number of nymphs and adults counted. Thrips counts were adjusted to the number of thrips per blossom by dividing the total number of thrips recovered by the total number of blossoms. Data were subjected to analysis of variance (ANOVA).

Thrips identified in both studies were at a 8:2 ratio of T. palmi/ F. occidentalis, respectively. In study 1, all treatments significantly reduced the mean number of thrips per blossom as compared with the control. There was no significant difference between Talstar and Tempo. In study 2, the double insecticidal dip was most effective significantly reducing the mean number of thrips per blossom. Although floragas reduced the mean number of thrips per blossom as compared with inflorescences held in a untreated fumigation chamber there was no significant difference between floragas fumigated inflorescences and inflorescences that received no treatment.

Treatment (study 1) AI (g/liter) No. thrips/blossom
Talstar F 0.20 0.07c
Tempo 2EC 0.04 0.07c
Tame 2.4EC 0.20 0.29b
Control -- 0.58a
Treatment (study 2) AI No. thrips/blossom
Double dip 0.1 g/liter 0.3c
Floragas 1.1 g/m3 0.6b
Control for dipa -- 1.0
Control for fumigantb -- 1.3a
Controlc -- 0.9ab

Data transformed to log10(x+1) and subjected to ANOVA (P< 0.01). Means followed by different letters in a column are significantly different by Waller-Duncan K-Ratio t test, k=100.
aDouble dip in water.
bFlowers in fumigation chamber without treatment.
cNo treatment.

"Hawai'i pesticide law prohibits the use of many insecticides as dips or drenches. Pesticide labels which prohibit dip usage or state the amount of product to be used per acre cannot be legally used as dips. Used dip solutions should be disposed by applying to approved crops or site in accordance with all label directions. Contact the Hawaii Department of Agriculture, Pesticide Branch if in doubt about legal use and proper disposal of insecticide dip solutions."

Reference to a company or product name does not imply approval or recommendation of the product by the College of Tropical Agriculture and Human Resources, Cooperative Extension Service University of Hawaii, or the United State Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable. All materials should be used in accordance with label instructions or manufacturer's directions.

Product Name: Floragas
Manufacturer's Name: NZIG special gases
Address: PO Box 30-202, Lower Hutt
Composition: 2.0% permethrin, 0.1% pyrethrum

Product Name: Mavrik Aquaflow
Manufacturer's Name: Sandoz Crop Protection Corp.
Address: 1300 E. Touhy Ave., Des Plaines, IL 60018
Composition: fluvalinate 2.0 lb active per gallon

Product Name: Talstar Flowable
Manufacturer's Name: FMC Corp.
Address: 2000 Market Street, Philadelphia, PA 19103
Composition: bifenthrin 0.67 lb active per gallon

Product Name: Tame 2.4EC
Manufacturer's Name: Valent U.S.A. Corporation
Address: 1333 NO. California St., Walnut Creek, CA 94598
Composition: fenpropathrin 2.4 lb active per gallon

Product Name: Tempo 2EC
Manufacturer's Name: Miles Inc.
Address: P.O. Box 4913, 8400 Hawthorn Road, Kansas City, MO 64120
Composition: cyfluthrin 2.0 lb active per gallon