obtained during field establishment with seashore dropseed plugs with the use of spray applications of oxadiazon (4.0 lb/acre) ( Baldos et al., 2010 ). The objective of this groundcover establishment study was to evaluate the response of weeds and cut stems
Scott B. Lukas, Joseph DeFrank, Orville C. Baldos, and Glenn S. Sakamoto
P.B. Goodwin and S. Beach
Ronstar® and Rout® are two of the most common and effective preemergent herbicides used by the nursery industry. However, there is some uncertainty as to what happens to the chemicals in nurseries that are recycling their runoff water. The fate of the chemicals has been studied in two nurseries that are completely dependent on recycled water. Negligible amounts were found in the recycled irrigation water. Most of each herbicide remained where it was applied, either close to the top in the substrate, or on the surface of the growing area, for periods of ≈4 months. Five months after application, <10% of oryzalin remained vs. ≈30% of the oxyfluorfen and oxadiazon. Less residue was produced if oxadiazon was applied when the pots were packed together after potting up, compared to application to spaced pots in the standing area. These herbicides are of low mammalian toxicity, and the main hazard is from contamination on the standing area after application, and from the top layer of substrate. To minimize any risk, we recommend that the herbicides be applied before the plants are spaced out on the growing area, and that staff handling the pots take suitable precautions, and in particular avoid inserting their unprotected hands into the top of the mix. Chemical names used: 2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one (oxadiazon); 4-(dipropylamino)-3,5,-dinitrobenzenesulfonamide (oryzalin); 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trichloromethyl)benzene (oxyfluorfen); tritium-labelled [N-(4-chloro-2-fluoro-S-(propargyloxy)-phenyl]-3,4,5,6-tetrahydrophthalimide [3H]THP.
Glenn R. Wehtje, Charles H. Gilliam, and Ben F. Hajek
Adsorption of 14C-labeled oxadiazon was evaluated in three soilless media and a mineral soil at concentrations between 0.1 and 100 mg·kg-1. Adsorption, which was at least 96%, was not influenced by absorbent type (medium vs. soil) or by oxadiazon concentration. However, desorption was greater in the media than in the soil. After five water extractions, 5.4% of the applied oxadiazon was recovered from media, but only 0.4% was recovered from the soil. In the soil and in two of the media, leaching with water failed to displace oxadiazon 2 cm below the surface to which it had been applied. No oxadiazon was detected below 4 cm in the third medium. Oxadiazon is sufficiently adsorbed to resist leaching-based displacement. Oxadiazon is not likely to enter the environment by escaping from treated containers. Chemical name used: 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-di-methylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon).
Orville C. Baldos, Joseph DeFrank, and Glenn Sakamoto
effective pre- and postemergence herbicides labeled for roadside use need to be identified. The studies in this preliminary and regional report characterized the response of tropical fimbry to the preemergence herbicides, oryzalin and oxadiazon, and to the
Orville C. Baldos, Joseph DeFrank, and Glenn Sakamoto
salt were assessed. The pre-emergence herbicides that were evaluated in the study were oxadiazon, oxyfluorfen, dithiopyr, and a commercial formulation consisting of trifluralin + isoxaben. Oxadiazon is an oxadiazole herbicide that has been labeled for
Patrick A. Jones, James T. Brosnan, Gregory K. Breeden, José J. Vargas, Brandon J. Horvath, and John C. Sorochan
prodiamine (1.1 kg·ha −1 ) and dithiopyr (0.6 kg·ha −1 ) can significantly impede bermudagrass stolon growth from sprigs; however, when the researchers applied oxadiazon at 3.4 kg·ha −1 , no significant reduction in percent cover was detected. Bingham and
Driss Iraqi, Isabelle Duchesne, and Jacques André Rioux
The objective of this study is to determine the phytotoxicity and efficiency of oxadiazon and sethoxydim used as herbicide in the production of four species of woody ornamental plants grown in containers. Four species were used: Cornus alba `Argenteo Marginata', Weigela florida `Rumba', Prunus x cistena and Thuja occidentalis `Woodwardii'. Six herbicide treatments were used (oxadiazon at 0,4 and 8 Kg (a.i.)/ha; sethoxydim at 0.000, 0.276 and 0.552 Kg (a.i.)/ha) and two controls were added (weeding and unweeding). The eight treatments were included in a complete block design replicated six times. This project was started in July 1993 and was conducted for three months. If phytotoxic symptoms were present on plants they were recorded and their effects on growth was measured. At the end of the experiment, weeds present in pots were identified, counted and their growth measured. Preliminary results showed that oxadiazon applied at rates of 4 and 8 Kg (a.i.)/ha had a good efficiency weed control in container production. Sethoxydim applied at rates of 0.276 and 0.552 Kg (a.i.)/ha had a good grass control. The two herbicides did not show phytotoxic symptoms on the for species used. The effects of herbicides on plant growth will be presented.
Travis W. Gannon, Matthew D. Jeffries, James T. Brosnan, Gregory K. Breeden, Kevin A. Tucker, and Gerald M. Henry
dithiopyr, indaziflam, oxadiazon, prodiamine, and pendimethalin are labeled for selective control of smooth crabgrass ( Digitaria ischaemum Schreb.) and large crabgrass [ Digitaria sanguinalis (L.) Scop.] in turf ( Anonymous, 2012a , 2012b , 2012c
Jason C. Fausey
The liverwort, marchantia (Marchantia polymorpha), and silver thread moss (Bryum argenteum) are two highly invasive and difficult to control pests in containerized ornamentals. Container trials were conducted evaluating marchantia and silve r thread moss control with preemergence and postemergence applications of chlorothalonil, captan, ammonium chlorides, hydrogen dioxide, flumioxazin, oxyfluorfen, pelargonic acid, acetic acid (vinegar), copper sulfate, cinnamaldehyde, prodiamine, and oxadiazon. Flumioxazin, oxyfluorfen, pelargonic acid, acetic acid, and oxadiazon provided acceptable preemergence and/or postemergence marchantia and silver thread moss control; however, no product provided acceptable control of these weeds at all evaluations. Under controlled environmental conditions marchantia and silver thread moss were controlled with flumioxazin, oxyfluorfen, pelargonic acid, acetic acid, and oxadiazon. In addition to providing postemergence control of these weeds, flumioxazin, oxyfluorfen, and oxidiazon also had residual activity when applied to potting media. However, the length and effectiveness of the preemergence control with flumioxazin, oxyfluorfen, and oxadiazon was dependant upon formulation. In a separate study comparing granular and sprayable formulations of flumioxazin, oxyfluorfen, and oxidiazon, results indicated control of established marchantia and silver thread moss was greater with sprayable formulations when compared with granular formulations. Similarly, sprayable formulations of these active ingredients enhanced residual marchantia and silver thread moss control. The granular and sprayable formulations of flumioxazin provided greater preemergence and postemergence control of marchantia and silver thread moss when compared with granular or sprayable formulations of oxyfluorfen and oxadiazon, and of the products evaluated, displayed the greatest level of activity against these weeds.
Pendimethalin and oxadiazon are used commonly to control crabgrasses (Digitaria spp.) in tall fescue (Festuca arundinacea Schreb.) and common bermudagrass [Cynodon dactylon (L.) Pers.]. A field experiment was conducted for 2 years to determine if reduced pendimethalin and oxadiazon application rates would control large crabgrass [D. sanguinalis (L.) Sco.] effectively in tall fescue and common bermudagrass. Oxadiazon applied at 1.1 kg a.i./ha in each of two applications at a 60-day interval (less than recommended rate) effectively controlled large crabgrass (≥93%), regardless of turfgrass species. Pendimethalin applied at 1.1 kg a.i./ha in each of two applications controlled large crabgrass in common bermudagrass effectively (≥90%) but not large crabgrass in tall fescue (47%). The difference in pendimethalin performance between the two species was attributed to the ability of common bermudagrass to compete more successfully than tall fescue with large crabgrass during late summer. Chemical names used: 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethy1)-l,3,4-oxadiazol-2-(3 H)-one (oxadiazon); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).