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.
Jason C. Fausey
P.H. Dernoeden and M.J. Carroll
In this field study, five preemergence and two postemergence herbicides were evaluated for their ability to hasten Meyer zoysiagrass (Zoysia japonica Steud.) sod development when sod was established from the regrowth of rhizomes, sod strips, and loosened plant debris. Herbicide influence on zoysiagrass re-establishment was examined using two postharvest field preparation procedures as follows: area I was raked to remove most above-ground sod debris, whereas in adjacent area II sod debris was allowed to remain in place. Herbicides that controlled smooth crabgrass [Digitaria ischaemum (Schreb.) Muhl.] generally enhanced zoysiagrass cover by reducing weed competition. Meyer established from rhizomes, sod strips, and loosened plant debris, and treated with herbicides, had a rate of sod formation equivalent to that expected in conventionally tilled, planted, and irrigated Meyer sod fields. Effective smooth crabgrass control was achieved when the rates of most preemergence herbicides were reduced in the 2nd year. Chemical names used: dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate (DCPA); 3,5,-pyridinedicarbothioic acid, 2-[difluromethyl]-4-[2-methyl-propyl]-6-(trifluoromethyl)∼S,S-dimethyl ester (dithiopyr); [±]-ethyl 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy] propanoate (fenoxaprop); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N-[1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine(pendimethalin);N3,N3-di-n-propyl-2,4-dinitro-6-[trifluromethyl)-m-phenylenediamine (prodiamine); and 3,7-dichloro-8-quinolinecarboxylic acid (quinclorac).
E. Jay Holcomb, Tracey L. Harpster, Robert D. Berghage and Larry J. Kuhns
A set of studies was established in Summer 1998 to determine the tolerance of field-grown cut flower species to specific preemergence herbicides, the effectiveness of weed control by those materials, and to determine if productivity of cut flowers is affected either by the herbicides or by colored mulches. Pendimethalin provided excellent early season weed control, but poor late-season control. It consistently caused injury at 4 lb a.i./A and sometimes at the 2 lb a.i./A rate. Oryzalin provided good to excellent weed control, but slightly injured celosia and zinnia when applied at 4 lb a.i./A. Napropamide provided excellent early season weed control, but marginally acceptable weed control later in the season. Though napropamide caused some injury to celosia early in the season when applied at the high rate, no injury to any of the plants was observed later in the season. Prodiamine and trifluralin were the overall safest of the herbicides, but they provided the weakest weed control. OH-2 was very effective when placed on the soil surface, but was less effective when placed on an organic mulch. The organic mulch was designed to keep the OH-2 particles from splashing on to the crop plant and injuring the plants. OH-2 tended to be safer placed on a mulch than on the soil surface, but statice was slightly injured even when a mulch was used.
Robert H. Stamps* and Annette L. Chandler
Common liverwort (Marchantia polymorpha L.) is an increasingly troublesome weed in containerized plant production. Postemergence applications were made to try to eradicate established stands of liverwort. Treatments consisted of sprays of quinoclamine at 1× and 2× rates and oxadiazon at the highest label rate, broadcast applications of sodium carbonate peroxyhydrate at 1x and 3x rates and four granular herbicides (flumioxazin, oxadiazon, oxyfluorfen + pendimethalin, and prodiamine) applied at label rates. The granular herbicides were applied both alone and with the sodium carbonate peroxyhydrate treatments. Herbicides were applied to common liverwort growing on an 80% aged pine bark: 20% Sphagnum peat-based soilless growing medium contained in 10-cm diameter plastic pots located in a double-poly covered greenhouse. At 2 weeks after treatment (WAT), control was best (93% to 100%) for both quinoclamine and the 3× peroxyhydrate treatments, intermediate (68% to 83%) for the 1× peroxyhydrate treatments, and not significant for any of the preemergence herbicides used alone. At 4 WAT, slight regrowth was evident in plots in which the treatments had an initial effect and the 1x peroxyhydrate + flumioxazin was as effective as the 3× peroxyhydrate and the 2× quinoclamine treatments. At 6 WAT, control was excellent in the 3× peroxyhydrate and 1× peroxyhydrate + flumioxazin treatments. Control was less, but still evident, in the quinoclamine and other 1× peroxyhydrate treated plots. While none of the treatments had completely eradicated common liverwort in all replications at 10 WAT, control was still excellent to good in many of the peroxyhydrate + preemergence herbicide-treated plots.
Robert H. Stamps
Six preemergence herbicides were applied twice a year at 1x and 2x rates for 2 years to leatherleaf fern [Rumohra adiantiformis (Forst.) Ching] starting from the time of rhizome planting. Predominant weeds present were Cardimine hirsuta, Erechrites hieracifolia, Oxalis stricta, and Phyllanthus tenellus. All herbicides, except pendimethalin and oxadiazon at the 1x rates, reduced weed biomass by 60% to 99% compared to the unweeded control during the fern bed establishment phase (year 1). During that period, hand-weeding times were reduced (51% to 95%) by prodiamine and dithiopyr at both rates, and oxadiazon and pendimethalin at 2x rates. During year 2, herbicides were of greatly reduced benefit due to reduced weed growth caused by the increasingly competitive fern. After 2 years, only 2x dithiopyr-treated plots had reduced yields compared to the hand-weeded controls. Herbicide treatments had no detrimental effects on frond postharvest longevity. In fact, fronds harvested from the 1x isoxaben-treated plots exhibited increased vase life compared to the controls.
Hannah M. Mathers, Luke T. Case* and Jennifer A. Pope
DNA herbicides are the most commonly used preemergents in container nursery crops. The objectives of this study were: 1) to investigate differences between DNA herbicide applied as granulars, directed sprays, or in combination with mulch (pine nuggets and cypress) on Taxus, Azalea and and Ilex root development; and, 2) to compare efficacy of the above treatments on common groundsel (Senecio vulgaris), large crabgrass (Digitaria sanguinalis), and annual bluegrass (Poa annua). The granular formulations tested were Barricade 65 WG (prodiamine) at 2.0 lbs active ingredient per acre (a.i./ac) and Treflan TR10 (trifluralin) at 2.0 lbs a.i./ac. The liquid formulations that were used as direct sprays and to treat the mulches were Surflan 4 AS (oryzalin) at 2.0 lbs ai/ac and Pendulum 3.8 CS (pendimethalin) at 3.0 lbs a.i./ac. Evaluations of phytotoxicity and efficacy were taken as rated scores, dry weights, and leaf area measures. Evaluations were taken at 30, 60, 90, and 120 days after treatment (DAT). Efficacy ratings were based on a 0-10 scale with zero being no control, 10 perfect control and 7 commercially acceptable. By 120 DAT, none of the treatments were commercially acceptable. Root (1.52 g) and shoot (3.75 g) weights indicate that Ilex was stunted the most vs. the control (2.42 g roots and 4.87 g shoots) by the direct spray of Pendulum 2X. The Azalea was most effected by the granular application of Barricade at the 2X rate (1.72 g for roots, 4.44 g for shoots) vs. the control (2.23 g for roots, 5.83 g for shoots). Taxus roots were most stunted by Treflan 1X (0.81 g) vs. control (1.01 g). Shoot weights were the lowest with Cypress+1X Pendulum (0.90 g), vs. the control (0.96 g); however, the Treflan 1X treatment gave the second lowest shoot weight for Taxus (0.91 g).
including prodiamine, dimethenamid-P + pendimethalin, and indaziflam applied as granular or sprayable formulations. Spray formulations of prodiamine and dimethenamid-P + pendimethalin were more effective than granular when applied alone, while indaziflam was
Adam Newby, James E. Altland, Charles H. Gilliam and Glenn Wehtje
+ oxadiazon (Regal O-O, 3% granular; Regal Chemical Co., Alpharetta, GA) at 3 lb/acre a.i., prodiamine (RegalKade, 0.5% granular; Regal Chemical Co.) at 1 lb/acre a.i., oxadiazon + prodiamine (RegalStar, 1.2% granular; Regal Chemical Co.) at 2.4 lb/acre a
fern, rochford's japanese holly fern, and southern wood fern were evaluated for their tolerance to selected preemergence-applied herbicides (Fain et al., p. 605 ) . Granular prodiamine proved to be a safe herbicide for all species tested in both 2004
Chuck Ingels and John Roncoroni
herbicides, applied 24 May (2 d after planting), were prodiamine (Barricade 65 WG; Syngenta Crop Protection, Greensboro, NC), pendimethalin (Pendulum AquaCap; BASF, Research Park Triangle, NC), oryzalin (Surflan AS; United Phosphorus, King of Prussia, PA