Skip to main content

Main menu

  • Home
  • Content
    • Ahead of Print
    • Current Issue
    • Special Issues
    • All Issues
  • Contribute
    • Submit to AUF
    • Author Guidelines
    • Reviewer Guidelines
  • About
    • Overview
    • Editorial Board
    • Journal Metrics
    • International Society of Arboriculture
  • More
    • Contact
    • Feedback
  • Alerts

User menu

  • Log in

Search

  • Advanced search
Arboriculture & Urban Forestry
  • Log in
Arboriculture & Urban Forestry

Advanced Search

  • Home
  • Content
    • Ahead of Print
    • Current Issue
    • Special Issues
    • All Issues
  • Contribute
    • Submit to AUF
    • Author Guidelines
    • Reviewer Guidelines
  • About
    • Overview
    • Editorial Board
    • Journal Metrics
    • International Society of Arboriculture
  • More
    • Contact
    • Feedback
  • Alerts
  • Facebook
  • Twitter
  • YouTube
  • LinkedIn
Research ArticleArticles

Phytotoxicity of Sunspray Ultra-Fine Spray OilR and Safer Insecticidal ConcentrateR Soap on Selected Ornamental Plants in Summer in North Florida and South Georgia

Russell F. Mizell
Arboriculture & Urban Forestry (AUF) August 1991, 17 (8) 208-210; DOI: https://doi.org/10.48044/jauf.1991.050
Russell F. Mizell
Associate Professor of Entomology, Agricultural Research and Education Center, University of Florida, Rt. 4, Box 4092, Monticello, Florida 32344
  • Find this author on Google Scholar
  • Search for this author on this site
  • Article
  • Figures & Data
  • Info & Metrics
  • References
  • PDF
Loading

Abstract

Listen

Two percent Sunspray Ultra-fine SprayR oil and Safer Insecticidal ConcentrateR soap were applied 5 times in separate treatments to 30 species of trees and shrubs growing in containers under commercial nursery conditions in north Florida. A similar test was conducted on 17 species of container-grown ornamentals in south Georgia. Horticultural oil and soap were applied at 10 day intervals beginning July 16, 1990. Plants were visually rated for phytotoxicity prior to the second through fifth application and 10 days after the fifth application. A third test of only three applications of horticultural oil or soap on 9 species of plants was conducted at Monticello, Florida beginning August 28, 1990. All the treatments were applied from 9:30 - 11:00 A.M. and daily temperatures were above 35° each day. No phytotoxicity was observed on any of the plants tested.

Environmental and sociological concerns that accompany the application of conventional pesticides for pest control have shifted research attention to the evaluation of alternative methods. Traditionally, horticultural oils have been recommended for use in the dormant season for insect and mite control on a variety of plant species. Phytotoxicity caused by the older, less refined brands of horticultural oils precluded their use during the active growing season. However, many new, more refined horticultural oils and soaps reduce the risk of phytotoxicity. Thus they have much promise as effective alternatives to conventional pesticides, fitting well into integrated pest management programs that seek to reduce pesticide use (1, 2, 3).

Previous work in Maryland (2) and New York (1) discussed the results of both phytotoxicity and efficacy studies using Sunspray 6E horticultural oil under summer conditions. Discoloration was observed on 6 of 52 species tested (two species of maple, a juniper, a blue spruce, a red oak and an arborvitae) and the authors urged caution if 2% Sunspray oil was used repetitively on these plants (2). Excellent control of spider mites, scales, whiteflies, aphids, and mealybugs using 2-3% Sunspray 6E oil was documented in New York (1). Some phytotoxicity from 3% oil to several walnuf (Juglans sp.) cultivars and some apparently permanent foliage discoloration to several juniper cultivars were reported (1).

Repellency and toxicity of horticultural oil to greenhouse whitefly, Trialeurodes vaporariorum (Westwood) have been reported (3). Also a reduction in the spread of an aphid-vectored virus was observed as a result of mortality to the aphid vectors from insecticidal soap (3).

The present study was initiated to test the potential for phytotoxicity to ornamental plants under the environmental conditions of commercial nurseries in south Georgia and north Florida.

Materials and Methods

Listen

Plants for the test were selected at random for uniformity of size and appearance from a large bed of similar plants. Plants in experiment 1 were located at a commercial nursery in Monticello, Florida. Three plants (replicates) from each cultivar in 2-3 gal. containers were grouped together for each of the 3 treatments: untreated control, 2% Sunspray Ultra-fine Spray oil, and 2% Safer Insecticidal Concentrate soap. Plants in experiment 2 were located at a commercial nursery in Cairo, Georgia. Plants normally grown under shade conditions (i.e. aucuba, camellia and azalea) were held under shade during the test. The Georgia plants were in 1 gal. containers. Plants in experiment 3 were tested at the author’s laboratory in Monticello, Florida. Plants in this test were in 1–2 gal. containers. All plants were held under commercial nursery conditions of overhead irrigation and fertilizer, etc. No cultural factors were added or changed during the course of the tests.

The oil and soap treatments were applied to plants with a SoloR backpack sprayer to runoff in a 2% solution at a volume of 100 gal. per acre. All applications were made between 9:30 and 11:00 A.M. on clear, sunny days. Daytime temperatures were typical of the season in south Georgia and north Florida reaching above 35°C and above 65% relative humidity in the afternoon on all spray dates. Plants in experiments 1 and 2 were sprayed on 16 July, 27 July, 7 August, 17 August and 28 August. Plants in experiment 3 were sprayed on 28 August, 7 September and 17 September. Evaluations were made on the spray dates before the application of the treatments and 10 days after the last application date. Treated plants were observed and compared to untreated control plants for any changes in appearance of the foliage. No pests were observed on the plants and efficacy against pests was not evaluated.

Results and Discussion

Listen

Table 1 lists the cultivars tested in the 3 experiments. No phytotoxicity was observed on any of the plants from the repetitive oil or soap treatments. Aucuba sprayed with oil did yellow slightly after the third application. However, the change in appearance was not enough to affect the salable quality. In experiment 2, the three 1 gal. boxwood plants treated with oil died during the test. Foliage symptoms indicated that apparently this resulted from a root disease and not the oil. Boxwoods in 2 gal. containers were tested again in experiment 3 and phytotoxicity was not observed. No change was observed in the color of the juniper cultivars tested. However, changes in juniper color often do not show up until cool weather in the deep South and this problem needs further consideration. Previous work reported discoloration of some juniper cultivars (2).

View this table:
  • View inline
  • View popup
Table 1.

List of plants sprayed with Sunspray Ultra-fine SprayR oil and Safer Insecticidal ConcentrateR soap in three separate experiments in south Georgia and north Florida during July-September, 1990.

View this table:
  • View inline
  • View popup
View this table:
  • View inline
  • View popup

It can be concluded from this test and the literature (1, 2) that the more refined horticultural oils can be safely used in the summer season in the eastern U.S. without general problems of phytotoxicity. Because of the large numbers of species and cultivars of plants grown in southern nurseries it will be impossible to rigorously test them all. No doubt some plants are sensitive to the oils and perhaps soaps and growers should spray a few plants of suspected sensitive species before applications to large numbers of plants. Phytotoxicity may be enhanced on plants that are under conditions of stress; although tests with horticultural oil on drought stressed plants indicated phytotoxicity to only a few cultivars (1,2). The application of adequate irrigation to plants before treatment with horticultural oil is highly recommended. The risk of phytotoxicity from horticultural oil may be higher to plants that have not yet hardened off during days in the fall when drastic changes in daily temperature often occur in the deep South.

Footnotes

Listen
  • ↵1. We thank David Walker of Wright Nursery, Cairo, GA and Fred Beshears and Rex Purvis of Simpson Nursery, Monticello, FL for providing the plants and a site to conduct these tests. Florida Agricultural Experiment Station Journal Series publication.

  • © 1991, International Society of Arboriculture. All rights reserved.

Literature Cited

Listen
  1. 1.↵
    1. Baxendale, R.W. and
    2. W.T. Johnson
    . 1988. Evaluations of summer oil spray on amenity plants. J. Arboric. 14:220–225.
    OpenUrl
  2. 2.↵
    1. Davidson, J.A.,
    2. S.A. Gill, and
    3. M.J. Raupp
    . 1990. Foliar and growth effects of repetitive summer horticultural oil sprays on trees and shrubs under drought stress. J. Arboric. 16:77–81.
    OpenUrl
  3. 3.↵
    1. Larew, H.G. and
    2. J.C. Locke
    . 1990. Repellency and toxicity of a horticultural oil against whiteflies on chrysanthemum. HortScience 25:1406–1407.
    OpenUrlAbstract/FREE Full Text
  4. 4.
    1. Zinnen, T.W. and
    2. J.W. Vachris
    . 1990. Insecticidal soap reduces infection of two mechanically transmitted plant viruses. Plant Disease 74:210–212.
    OpenUrl
PreviousNext
Back to top

In this issue

Arboriculture & Urban Forestry (AUF)
Vol. 17, Issue 8
August 1991
  • Table of Contents
  • Index by author
Print
Download PDF
Email Article

Thank you for your interest in spreading the word on Arboriculture & Urban Forestry.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Phytotoxicity of Sunspray Ultra-Fine Spray OilR and Safer Insecticidal ConcentrateR Soap on Selected Ornamental Plants in Summer in North Florida and South Georgia
(Your Name) has sent you a message from Arboriculture & Urban Forestry
(Your Name) thought you would like to see the Arboriculture & Urban Forestry web site.
Citation Tools
Phytotoxicity of Sunspray Ultra-Fine Spray OilR and Safer Insecticidal ConcentrateR Soap on Selected Ornamental Plants in Summer in North Florida and South Georgia
Russell F. Mizell
Arboriculture & Urban Forestry (AUF) Aug 1991, 17 (8) 208-210; DOI: 10.48044/jauf.1991.050

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Share
Phytotoxicity of Sunspray Ultra-Fine Spray OilR and Safer Insecticidal ConcentrateR Soap on Selected Ornamental Plants in Summer in North Florida and South Georgia
Russell F. Mizell
Arboriculture & Urban Forestry (AUF) Aug 1991, 17 (8) 208-210; DOI: 10.48044/jauf.1991.050
del.icio.us logo Twitter logo Facebook logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One
Bookmark this article

Jump to section

  • Article
    • Abstract
    • Materials and Methods
    • Results and Discussion
    • Footnotes
    • Literature Cited
  • Figures & Data
  • Info & Metrics
  • References
  • PDF

Related Articles

  • No related articles found.
  • Google Scholar

Cited By...

  • No citing articles found.
  • Google Scholar

More in this TOC Section

  • Right Appraisal for the Right Purpose: Comparing Techniques for Appraising Heritage Trees in Australia and Canada
  • Urban Tree Mortality: The Purposes and Methods for (Secretly) Killing Trees Suggested in Online How-To Videos and Their Diagnoses
  • Unmanned Aerial Vehicle (UAV) in Tree Risk Assessment (TRA): A Systematic Review
Show more Articles

Similar Articles

© 2025 International Society of Arboriculture

Powered by HighWire