Late season control of whitefly is problematic in many production ranges as systemic insecticides may not provide full season control. Most commercially available contact insecticides are not labeled for use on fully colored poinsettia, Euphorbia pulcherrima, plants due to potential phytotoxicity or residue on colored bracts. Recent formulation changes in TriStar make late season applications possible. This study assessed phytotoxicity and residue impacts of two formulations of TriStar on potted poinsettias. On 4 Aug. 2004, rooted cuttings of 47 poinsettia cultivars obtained from four commercial suppliers were transplanted into pots containing a soilless medium. A total of 235 cuttings were used to arrive at five pots per cultivar. Plants were grown using standard production techniques. On 11 Nov. 2004, all plants were fully colored and treated with TriStar 70 WSP or TriStar 30SG at maximum label rates. Phytotoxicity and residue levels were assessed 7 days later using a 1 to 9 visual scale. Overall the formulations had few negative impacts on poinsettias. Phytotociticy ratings were minimal for most cultivars; however, some cultivars, such as `Silverstar Red' expressed an elevated level of phytotoxicity. Dark colored cultivars showed more residue than light colored cultivars. The TirStar 30SG formulation had the least amount of residue. TriStar 30SG may be an acceptable insecticide for late season control of whitefly on poinsettia crops. Producers are cautioned to test cultivars for phytotoxicity before applying to an entire crop as some cultivars are sensitive to TriStar 30SG.
Abstract
Five plant species [burford holly (Ilex cornuta Lindl. and paxt. ‘Burfordii’) golden-rain tree [Koelreuteria elegans (Seem. A.C. Sm.], ligustrum (Ligustrum japonicum Thunb.), hibiscus (Hibiscus rosa-sinensis L.), and podocarpus (Podocarpus macrophyllus Thunb.)] were arranged in a 5 × 5 × 5 factorial experiment and sprayed with 4 pesticides (dimethoate, dicofol, malathion, oxydemeton methyl) and water alone, as well as 4 chemicals [ancymidol, ethephon, gibberellic acid (GA3)] and water alone. Growth regulators increased pesticide phytotoxicity ratings, whereas the antitranspirant had no effect on phytotoxicity ratings.
the United States in 1989 ( Dennis, 2000 ). Most of the other chemicals have been less satisfactory as a result of inconsistent flower thinning or foliar phytotoxicity. However, fruit thinning of apples and peaches by chemical thinners may be
The effects of hydrogen cyanamide (H2CN2) on budbreak and phytotoxicity of l-year-old potted peach trees [Prunus persica (L.) Batsch. cv. Redhaven] over a wide range of concentrations at several stages of dormancy were studied. Endodormancy (180° GS; degree growth stage) began on 1 Oct. Maximum intensity of endodormancy (270° GS) was reached after the plants were exposed to 320 chill units on 1 Nov., and 50% of the buds were broken at 860 chill units on 1 Dec. Five concentrations of H2C N2 (0, 0.125, 0.25, 0.5, and 1.0 m) were applied on 1 and 15 Oct., 1 and 15 Nov., and 1 and 15 Dec. 1990. All concentrations promoted budbreak; however, percent budbreak and phytotoxicity depended on concentration and timing of application. The most effective concentration (greatest budbreak and lowest phytotoxicity) was 0.125 m H2CN2 on all treatment dates. Phytotoxicity was evident at all application dates but was greatest at the highest concentrations. Plants were most resistant to H2CN2 at maximum intensity of endodormancy. Hydrogen cyanamide-induced budbreak was highest during the later stages of endodormancy (295 to 315° GS). Treatments applied during the ecodormancy stage (340° GS) inhibited and delayed budbreak and damaged buds and stems. Chemical name used: hydrogen cyanamide (H2CN2, Dormex).
In Florida, pesticides, nutritional and growth regulators are often sprayed in tank mixes to reduce sprayer use. Many individual spray components are phytotoxic and result in spray burns in combination or if applied with adjuvants. The toxicity level of standard spray materials is not known and new product testing for phytotoxicity is not routine. Three tests were developed to allow testing of cellular and whole fruit susceptibility to spray chemicals. Cell suspension cultures initiated from `nucellar derived' embryonic callus of `Hamlin' sweet orange were grown in log phase for 2 weeks with various levels of test chemicals. Fresh weight increase was measured. Peel disks of orange or grapefruit were grown for 4 weeks on solid media. Color changes and callus growth were used to evaluate phytotoxicity. Dilute sprays and droplet applications to on-tree-fruit were used to evaluate individual and combinations of chemicals with and without spray adjuvants. The 3 tests combined effectively demonstrated levels of phytotoxicity and are useful for testing new citrus production chemicals.
researched the efficacy of EF, PH 3 , and their combination for control of purple scum springtails on celery. In this preliminary study, optimal fumigant concentration, exposure period, and evaluation of phytotoxic damage to celery bunches are reported
Japanese plum (Prunus salicina Lindel. `Casselman') trees exposed to three atmospheric ozone partial pressure treatments were sprayed with a summer application of Volck Supreme oil (1% aqueous solution) to control an outbreak of spider mites (Tetranychus spp.). Phytotoxic effects were observed on the foliage of trees in the plots exposed to ambient or higher atmospheric ozone partial pressures 5 days following spray application. Foliage on trees exposed to 0.044 and 0.081 μPa·Pa-1 ozone [12-h mean (8 Apr. to 12 June 1992)] partial pressures developed water spotting and more foliage abscission than trees exposed to charcoal-filtered air (0.024 μPa·Pa-1 ozone). Thus, ozone air-pollution stress may predispose plants to increased phytotoxicity from summer oils.
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.
The use of shredded bark, wood chips, and other organic mulches to conserve water and moderate soil temperatures is a common practice in landscape maintenance. Four mulch materials (cottonseed hulls, cypress pulp, pine bark, and pine straw) were examined to determine effects on plant growth and soil conditions in annual flower beds during a 1-year rotation of warm season to cool season annuals. Inhibited plant growth was observed in pine bark treatments at the conclusion of the growing season for both plantings. Effects on soil conditions were insignificant over the year-long study in pine bark treatments. To further investigate potential phytotoxic effects of pine bark and other mulch used in the initial study, a seed bioassay was performed to determine the influence of mulch extracts in solution on germination and primary root elongation.
Handgun treatments of abamectin and oil applied between mid-June and late August caused distinct epidermal rings where drops of spray liquid dried on the surface of pear fruit (Pyrus communis L.). The severity of epidermal injury was related to the concentration of oil in the abamectin spray mixture (abamectin applied without oil caused no fruit damage). Of six pear cultivars tested, `Anjou' was most susceptible to injury, followed by `Cornice' and `Bartlett'. `Sensation Red Bartlett', `Bosc', and `Seckel' showed little or no phytotoxicity symptoms from abamectin and oil treatments with oil concentrations from 0.125% to 2.0% (v/v). On sensitive cultivars, the concentration of oil should not exceed 0.25% (v/v) when combined with abamectin to reduce the risk of epidermal injury. Oil at 0.25% provides for adequate leaf penetration of abamectin and results in commercially acceptable spider mite (Tetranychus urticae Koch) control. Chemical names used: avermectin B1 (abamectin).