Insecticidal soap and horticultural oil have been used since the late 1800s to manage soft-bodied insect pests of fruits, shade trees, and ornamental plants ( Weinzierl, 2000 ). Insecticidal soaps are made of a potassium salt of a plant
Carlos R. Quesada and Clifford S. Sadof
Fredric Miller and Susan Uetz
Horticultural oil and insecticidal soap were as effective as conventional insecticides and miticides in controlling a variety of sap-feeding insects and mites on common greenhouse crops. Neem extract (Margosan-O or Azatin) was less consistent and provided intermediate to good control of a variety of sap-feeding insects and mites on common greenhouse crops. Except for purple heart (Setcreasea purpurea K. Schum. & Sydow) and wax ivy (Hoya carnosa R. Br.), repetitive sprays of horticultural oil, insecticidal soap, and neem extract (Azatin) did not seem to cause any noticeable phytotoxicity or effect the growth of 52 species or cultivars of bedding plants and 13 species of foliage plants examined in this study. Repetitive sprays of horticultural oil and insecticidal soap significantly affected plant height and final quality of some poinsettia cultivars evaluated in this study.
D.J. Schuster, T.F. Mueller, J.B. Kring, and J.F. Price
A new disorder of fruit has been observed on tomato (Lycopersicon esculentum Mill.) in Florida. The disorder, termed irregular ripening, was associated with field populations of the sweetpotato whitefly, Bemisia tabaci (Gennadius) and is characterized by incomplete ripening of longitudinal sections of fruit. An increase in internal white tissue also was associated with whitefly populations. In field cage studies, fruit on tomato plants not infested with the sweetpotato whitefly exhibited slight or no irregular ripening, whereas fruit from infested plants did. Fruit from plants on which a whitefly infestation had been controlled before the appearance of external symptoms exhibited reduced symptoms compared to fruit from plants on which an infestation was uncontrolled.
Arnold H. Hara, Trent Y. Hata, Victoria L. Tenbrink, Benjamin K.S. Hu, and Mike A. Nagao
Postharvest treatments significantly reduced or eradicated pests on various tropical cut flowers and foliage. Immersion in water at 49° C for 10 minutes killed armored scales on bird of paradise leaves, Strelitzia reginae Banks, as well as aphids and mealybugs on red ginger, Alpinia purpurata (Vieill.) K. Schum. Vapor heat treatment for 2 hours at 45.2° C provided quarantine security against armored scales on bird of paradise leaves. A 5 minute dip in fluvalinate combined with insecticidal soap eliminated aphids and significantly reduced mealybugs on red ginger. A 3 minute dip in fluvalinate, a 3 minute dip in chlorpyrifos, or a 3 hour fog with avermectin-B significantly reduced thrips on orchids, Dendrobium spp., without injury to the flowers. No postharvest treatment was both effective and nonphytotoxic on all commodities.
C.S. Vavrina, P.A. Stansly, and T.X. Liu
Household detergents were evaluated in field studies on fresh-market tomato (Lycopersicon esculentum Mill.) for insecticidal and phytotoxic effects. Laboratory bioassays were used to examine the toxicity of a household liquid dish detergent on small nymphs of silverleaf whitefly, Bemisia argentifolii Bellows and Perring. The detergents tested proved to be more toxic to whitefly nymphs than the commercial insecticidal soap. Detergent treatments were applied to tomato with a commercial high pressure hydraulic sprayer at 0%, 1%, 2%, 4%, and 8% (by volume) initially and at 0%, 0.25%, 0.5%, 1.0%, and 2.0% (by volume) in subsequent tests. As detergent rate, frequency of application, or both increased, plant dry weight accumulation and fruit yield decreased. Applying detergent also increased time to fruit maturity. A once-a-week application of 0.25% to 0.5% detergent initially applied 2 weeks after transplanting alleviated phytotoxicity and yield reduction problems.
Susan Parent and Annie Duval
Increased use of VAM for pot-grown cultures has sustained certain inquiries as to the compatibility of pesticides and biocontrol agents with this novel practice. Asparagus, Boston fern, geranium, and poinsettia were cultivated in a peat-based medium (SB-Mix) with various fungicides, insecticides, and insect predators. Each plant consisted of an individual trial. All treatments were randomly set up in a complete block experimental design consisting of a noninoculated control and pre-inoculated with Glomus intraradices, in combination with the different pesticides used for a given plant species. Commonly used pesticides in greenhouses were chosen, and the concentration applied was as recommended by the manufacturer. A control, consisting of water, was included with the pesticides tested. The effect of a given pesticide varied from one plant species to another concerning root colonization by the VAM and plant growth. The poinsettia growth results were significantly superior with the water-treated plants than with those that received insecticidal soap, dienochlor, and dicofol on a regular basis. Colonization rates, however, were low with all treatments, but significantly lower with oxine benzoate. Growth parameters and colonization rates of geranium, Boston fern, and asparagus showed no significant differences between water and pesticide treatments, even those treated with benomyl, which has been reported in the past to reduce colonization rates. These results show that a good pesticide and insect predator integration control program will not alter the VAM colonization rates.
D. Casey Sclar, Daniel Gerace, Andrea Tupy, Karen Wilson, S. Aaron Spriggs, R. Jason Bishop, and Whitney S. Cranshaw
Experiments conducted in greenhouse and field environments investigated the acute and chronic phytotoxic effects of several house-hold and commercially available soaps, detergents, and oils applied to tomato (Lycoperiscum esculentum Mill.). In addition, the effect of these treatments on greenhouse whitefly, Trialeurodes vaporarium (Westwood), was investigated. In the greenhouse experiments, the number of whiteflies observed was negatively correlated with phytotoxicity (i.e., higher phytotoxicity = fewer whiteflies). Ivory Clear detergent at two rates of application (0.5% or 2.0%) caused the greatest phytotoxicity to seedling tomato plants. Addition of vegetable oils to a 0.5% Ivory Clear detergent solution did not affect phytotoxicity to the plants. While commercially available insecticidal soap (M-Pede) and a neem seed extract (Margosan-O) had little phytotoxicity, they provided only a slight reduction of whitefly populations. A field experiment conducted in the absence of insect pressure showed phytotoxic effects to tomato plants as a result of continued treatment with New Ivory detergent. Significantly lower yield from this treatment resulted from reduced flower and/or fruit production. None of the other compounds in the field experiment significantly affected the yield of tomato plants.
Michelle L. Bell, James R. Baker, and Douglas A. Bailey
Potential phytotoxicity and plant growth-regulating activity of insecticidal dips for poinsettias was investigated by dipping, then growing unpinched, rooted cuttings of `Red Sails', `Freedom', and `V-14 Glory' in the following insecticidal emulsions for five durations: 2% insecticidal soap (Safer's), 2% horticultural oil (Sunspray Ultrafine), fluvalinate (Mavrik Aquaflow), oxythioquinox (Joust), kinoprene (EnstarII), azadirachtin (Margosan-O), fenoxycarb (Precision), and an oil-carrier formulation of Beauveria bassiana (Naturalis-L). Dips in soap, oxythioquinox, Naturalis-L, and oil were phytotoxic to all three cultivars. Also, kinoprene and fenoxycarb were phytotoxic to `Red Sails'. At dip durations of 10 s and greater, soap, Naturalis-L, and oil were phytotoxic. Oxythioquinox was phytotoxic at durations of 1 min, 15 min, and 1 h. Only fluvalinate was not phytotoxic as a 4-h dip. After 2 weeks, plants dipped in oxythioquinox, Naturalis-L, and oil were stunted. By week 4, differential cultivar effects were seen: six dips (all but fluvalinate and azadirachtin) stunted growth of `Red Sails', whereas only Naturalis-L and oil retarded growth of `V-14 Glory'. Six weeks after treatment, growth of all cultivars was stunted by oxythioquinox, Naturalis-L, and oil, but was not retarded by fluvalinate or azadirachtin. Dip duration significantly affected growth by weeks 4 and 6, when all durations of Naturalis-L and oil reduced growth. Additionally, 4-h dips of oxythioquinox and kinoprene stunted plants after 4 weeks, and 1- and 4-h dips of oxythioquinox, kinoprene, and fenoxycarb adversely affected growth after 6 weeks.
Michelle L. Bell, James R. Baker, and Douglas A. Bailey
Since whiteflies preferentially oviposit on the newest leaves, it is the early life stages that are most likely to be present on poinsettia cuttings from infested stock or infested during rooting. This study evaluated efficacy of insecticidal dips against eggs and first nymphal instars of the silverleaf whitefly, Bemisia argentifolii. Dip efficacy was investigated by dipping rooted cuttings of whitefly-infested `Freedom' in the following insecticide emulsions: 2% insecticidal soap (M-Pede), 1% horticultural oil (Ultrafine), fluvalinate (Mavrik), oxythioquinox (Joust), kinoprene (EnstarII), azadirachtin (Margosan-O), fenoxycarb (Precision) and imidacloprid (Merit). Two dip durations, 10 seconds and 1 hour, were tested for each insecticide. Water dips for the two durations were used as control treatments. Fenoxycarb and azadirachtin dips for durations of 10 seconds and 1 hour and oxythioquinox dips for 1 hour resulted in greater egg mortality than the other treatments. No insecticide/dip duration treatment gave 100% mortality of eggs. Dips found to be efficacious killed proportionately fewer eggs than first instar nymphs.
`Caruso' tomatoes were grown in a glass greenhouse in Winter and early Spring 1991. All plants were grown in 16-liter nursery pots. Half the plants were grown in a conventional peat-lite medium (Profi-mix) and were fertilized with synthetic water-soluble fertilizer containing micronutrients and (in ppm) 187 N, 46 P, 278 K, 177 Ca, and 48 Mg. The other plants were grown in a potting medium composed of 1 mature compost (chicken manure and leaves): 1 loam: 2 vermiculite (by volume); this medium was amended with 1.5 kg bone meal (2N–10P–0K) and 3 kg dolomitic lime/m3. The “organic” treatment was fertilized with a fish emulsion solution containing (in ppm) 150 N, 13 P, and 25 K. The experiment was repeated in 1992 with `Capello'. In both years, fruit were harvested around the half-ripe to three-quarters ripe stage. All insect control was with insecticidal soap and bio-control agents. A blind taste test was conducted on campus in both years. In 1991, of 70 participants, 73% preferred the “conventional” tomatoes, 20% preferred the organic tomatoes, and 7% expressed no preference. In 1992, of 105 participants, 67% preferred the “conventional” tomatoes, 24% preferred the organic tomatoes, and 10% expressed no preference.