Response of Established Landscape Plants to Uniconazole

Abstract

<jats:p>Uniconazole was applied once as a soil drench (15, 30, or 45 mg a.i./plant) or foliar spray (500, 1000, or 1500 mg liter<jats:sup>-1</jats:sup>, about 175 ml/plant) to established, field-grown thorny elaeagnus <jats:italic>(Elaeagnus pungens</jats:italic> Thunb. Fruitlandii) and leyland cypress [× <jats:italic>Cupressocyparis leylandii</jats:italic> (A.B. Jacks. &amp; Dallim.) Dallim. &amp; A.B. Jacks]. At the end of the second growing season following treatment, shoot dry weights (SDW) of thorny elaeagnus decreased with increasing rates of drench-applied uniconazole, while SDW of plants receiving the foliar application were not affected by increasing rates. Growth indices of leyland cypress, determined twice during the first growing season and at the end of the second growing season, were not influenced by application method or rate. Uniconazole applied as a soil drench at 15 to 45 mg a.i./plant suppressed growth of established thorny elaeagnus for at least two growing seasons, but leyland cypress was not affected by uniconazole drench or foliar spray at tested rates. No phytotoxicity was observed on either species in any treatment during the experiment.</jats:p>

Controlling Growth of Tabletop Christmas Trees with Plant Growth Retardants

“…Uniconazole applied as a soil drench to 3-year-old loblolly pine reduced elongation by 55%, as determined 3 months after treatments ended (Barnes and Kelley, 1992). Keever and West (1992) applied uniconazole as a soil drench to containerized leyland cypress (x Cupressocyparis leylandii). Growth was reduced as much as 48%.…”

“…Considerable research has been performed on PGRs to determine their effectiveness in controlling growth of conifer species (Asher, 1963;Dunberg and Eliasson, 1972;Groninger and Seiler, 1997;Hare, 1982;Keever and West, 1992;Kuo and Pharis, 1975;Ruddat and Pharis, 1966;Ruter, 1994;Van den Driessche, 1989, 1996Weston et al, 1980). In general, the emphasis of these studies has been to determine the effectiveness of PGRs to reduce transplanting stress or as a means of height control under utility rights-of-way.…”

Response of Forsythia ×intermedia `Spectabilis' to Uniconazole. II. Leaf and Stem Anatomy, Chlorophyll, and Photosynthesis

“…Plant growth retardants (PGRs) have the potential to reduce vegetative growth and pruning frequency of woody landscape species. Uniconazole, a triazole, can effectively retard growth of several woody landscape species including 'Spectabilis' forsythia without injury (Keever and West, 1992;Norcini and Knox, 1989;Thetford et al, 1995;Warren et al, 1991). Little information is available, however, on the effects of foliar application of uniconazole on woody plant morphology or anatomy [Wang and Gregg, 1989 (hibiscus, Hibiscus rosa-sinensis L.); McDaniel et al, 1990 (Poinsettia, Euphorbia pulcherrima Willd.)]…”

Response of Forsythia × itermedia `Spectabilis' to Uniconazol. I. Growth; Dry-matter Distribution; and Mineral Nutrient Content, Concentration, and Partitioning

“…Increasing costs and restrictions on disposal of organic wastes in landfills has stimulated interest in the use of plant growth retardants to limit vegetative growth and reduce pruning frequency of woody landscape plants. Research has demonstrated the potential use of uniconazole (Valent U.S.A., Walnut Creek, Calif.), as an economical method of reducing plant growth in established landscape plantings (Keever and West, 1992) or as a component of container production regimes for woody landscape species (Norcini and Knox, 1989;Warren 1990;Warren et al, 1991).…”

“…Uniconazole is a member of a group of compounds known as triazoles which retard growth of several ornamental species (Bailey and Miller, 1989;Keever and West, 1992;Norcini and Knox, 1989;Wang and Gregg, 1989;Warren 1990). Triazoles are xylem mobile and when applied to roots, young stems, and to a lesser extent the youngest leaves, are absorbed and translocated acropetally to the leaves (Reed et al, 1989;Sterrett, 1988).…”