Resource Information

Phytotoxicity of Insecticides on Dendrobium Orchids, Hawaii, 1994  

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

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

DENDROBIUM ORCHID: Dendrobium 'Uniwai Princess',
'Uniwai Pearl', 'Uniwai Supreme'

Phytotoxicity trials were conducted from 20 Sep through 17 Dec 1993 (trial 1) at a commercial dendrobium farm in Hilo, Hawaii and 26 Jul through 26 Sep 1994 (trial 2) at the University of Hawaii Waiakea Experiment Station in Hilo, Hawaii. Tests were conducted on mature plants (approximately 3.5 ft in height) growing in 2 gal. bags under 6 mil. clear FVG 3HLFI polyethylene film covering. Treatments consisted of 36 plants of each cultivar. In trial 1, six weekly insecticide applications were made to the flowers and foliage beginning 20 Sep ending 25 Oct. In trial 2, three weekly applications were made beginning 26 Jul ending 10 Aug. Insecticides were applied using a Solo backpack sprayer (Solo Inc., Newport News, VA) equipped with an 8004 Teejet nozzle at 40 psi (377 GPA). The spreader-sticker Ad-here was added to all treatments including the control at a rate of 5 fl.oz./100 gal. Phytotoxicity was evaluated weekly and continued for five weeks after the last insecticide application. In addition, one week after the last insecticide application 5 inflorescences were harvested randomly from each plot and evaluated for vase life. Data were taken on the number of days inflorescences remained intact (start of blossom wilt or senescence) and end of vase life ( > 50% of blossoms affected). Treatment means were compared by t test and the standard deviation calculated.

In trial 1, both insecticides were not phytotoxic after six weekly insecticide applications. In addition, there was no significant difference between treated and untreated inflorescences in the number of days to the start of blossom senescence. Vase life of ‘Uniwai Supreme’ inflorescences from Talstar plots was significantly longer than flowers harvested from the control. In trial 2, Azatin EC was not phytotoxic at the tested rates. There was no significant difference in blossom drop and vase life.

lb. AI/100 gal ‘Uniwai Supreme’
Initiation of Vase life blossom drop
‘Uniwai Pearl’
Initiation of Vase life blossom drop
‘Uniwai Princess'
Initiation of Vase life blossom drop
Trial 1      
Talstar + 0.4/0.5 Orthene 11.0+0.0a 30.0+4.8 11.0+0.0a 36.4+3.6 13.8+3.8 31.2+1.8
Talstar 0.4 13.8+3.8 3 2.8+1.8a* 15.0+3.0 36.0+5.5 10.6+4.3 29.2+6.3
Control 13.8+3.8 2 7.8+3.8b 15.0+3.0 34.4+2.2 12.4+3.1 27.8+9.4
Trial 2      
Azatin EC 0.03 15.2+1.8 25.6+3.1 16.4+4.6 31.0+5.9  
Azatin EC 0.06 (2X) 15.6 + 4.1 25.0 + 2.7 17.2+3.9 28.4+5.9  
Control 18.8+7.7 28.4+3.1 14.8+4.4 25.6+5.9

*, significantly different from the control by ttest P< 0.05.
a Data not analyzed because all values same for one class.


Use pesticides safely. Follow the pesticide label. Consult with the Cooperative Extension Service or the Hawai'i State Department of Agriculture for authorized special local need registrations or additional information. The user is responsible for the proper use, application, storage, and disposal of pesticides.

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: Ad-here
Manufacturer’s Name: JR Simplot
Address: P.O. Box 198, Lanthrop, CA 95330
Composition: Alkylarylpolyoxethylene glycol, glycol ethers, combined fatty acids, bis (2-ethylhexyl) benzene dicarboxylate, isopropanol 97.6%

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: Orthene Turf, Tree & Ornamental
Manufacturer’s Name: Valent Corp.
Address: 1333 W. California St., Walnut Creek, CA 94596
Composition: acephate 75% active by weight

Product Name: Azatin EC
Manufacturer’s Name: AgriDyne Technologies Inc.
Address: 2401 So. Foothill Dr., Salt Lake City, UT 84109
Composition: azadirachtin 0.265 active per gallon