Proceedings of the Sixty-first Annual Meeting of the Northeastern ...
Proceedings of the Sixty-first Annual Meeting of the Northeastern ... Proceedings of the Sixty-first Annual Meeting of the Northeastern ...
24 EFFECTS OF EMERGENCE PERIODICITY ON GROWTH AND FECUNDITY OF HORSEWEED. J.T. Dauer, The Pennsylvania State Univ., University Park, B.A. Scott and M.J. VanGessel, Univ. of Delaware, Georgetown, and D.A. Mortensen, The Pennsylvania State Univ., University Park. ABSTRACT The dispersal ability of winter annual and summer annual biotypes of horseweed (Conyza canadensis) was assessed along a 400 km latitudinal gradient between Pennsylvania and Delaware. Dispersal ability was defined by time of seed set, plant height and fecundity. Earlier seed set can result in greater opportunities for fall establishment and taller plants increase seed release height and impact dispersal distance. Greater fecundity increases the opportunities for populations to sample diverse environments and establish satellite populations. Sites were located in central and southeastern Pennsylvania, and central and southern Delaware with trials initiated in fall 2005 and replicated in fall 2006. Plots were arranged in a randomized complete block with four replications of two fall and two spring cohorts. Early and late cohorts were determined by germination before or after October 1st (fall) and April 15th (spring). Ten plants were randomly selected in each replicate, marked, and revisited biweekly to record plant height and percent flowering. Following seed release, final plant height was measured and capitula per plant were counted to estimate seed production. The late fall cohort was eliminated due to lack of overwintering success in Pennsylvania populations and data were averaged within a plot. In 2005-2006 seed set initiation progressed from south to north, however the next year, Pennsylvania populations set seed earlier than either Delaware location. Location and treatment significantly affected final plant height (P
25 COMPARISON OF INTEGRATED WEED MANAGEMENT STRATEGIES IN CHRISTMAS TREE PLANTATIONS. M.W. Marshall, B.H. Zandstra, Michigan State Univ., East Lansing, and R.J. Richardson, North Carolina State Univ., Raleigh. ABSTRACT Since Christmas tree value is based mainly on their appearance, pests that reduce the visual quality of trees are intensively managed. Michigan Christmas tree growers rely heavily upon pesticides, including atrazine and simazine, to control these pests. However, atrazine and simazine have ground and surface water concerns. Field studies were conducted in 2005 and 2006 to determine integrated weed management programs utilizing alternatives to replace and/or reduce triazine use. The treatments were flumioxazin+glyphosate at 0.28 and 1.12 kg/ha broadcast or within the row, organic mulch, organic mulch+glyphosate at 0.84 kg/ha, hard fescue (Festuca brevipila 'Aurora Gold') groundcover, white clover (Trifolium repens L.) groundcover, mechanical control system, mechanical control+glyphosate at 0.84 kg/ha, and an untreated control. Organic mulch consisted of a coarsely ground pine bark and was applied as a 91 cm wide band in the tree rows. Hard fescue and white clover were broadcast seeded into plots in the fall of each year at rates of 250 and 7 lb/A, respectively. Mechanical control treatments were imposed using a hand-operated mower between and within the tree rows. Flumioxazin and glyphosate treatments were applied on April 19, 2005 and April 11, 2006. Glyphosate+mechanical treatments were imposed in June, July, and August of each year. Experimental design was a randomized complete block design with 4 replications. Conifer injury was evaluated 8, 12, and 16 wk after treatment (WAT) on a 0-100% scale (0 = no injury and 100 = crop death). In addition, plots were visually evaluated for % cover of each weed. Overall ground cover in the 2005 site was denser than in the 2006 site. In general, hard fescue established and provided a denser groundcover than white clover. In the hard rescue plots, other weed species did not thrive in the plots; however, quackgrass (Elytrigia repens (L.) Nevski.) was observed at a low percentage of the total groundcover (8%). This indicates that a living mulch, such as hard fescue inhibited light-dependent weed seed germination. The organic mulch provided excellent groundcover until weed seeds started germinating within the mulch layer. In the mulch+glyphosate treatment, glyphosate eliminated most of the weeds emerging between the rows and within the mulch layer. Plots receiving flumioxazin + glyphosate treatments, regardless of the broadcast or strip application, remained bare with the exception of a few weeds throughout the growing season. Conifer injury was virtually non-existent in all treatments. Similar to 2005, hard fescue provided greater than 65% groundcover throughout the growing season. Common milkweed (Asclepias syriaca L.) was observed in some of the hard fescue plots (less than 10%). The use of a living groundcover, such as hard fescue, is a beneficial cultural control because it minimizes herbicide use while providing suppression of light germinating weed species. For suppression of perennials, such as quackgrass and common milkweed, hard fescue is also tolerant to over-the-top applications of glyphosate. 7
- Page 1 and 2: 1 Proceedings of the Sixty-first An
- Page 3 and 4: 3 NORTHEASTERN WEED SCIENCE SOCIETY
- Page 5 and 6: 5 SECTION CHAIRS Agronomy Chair: J.
- Page 7 and 8: 7 CARFENTRAZONE AND QUINCLORAC FOR
- Page 9 and 10: 9 THE EFFICACY AND CROP TOLERANCE O
- Page 11 and 12: 11 EVALUATION OF HERBICIDES FOR CON
- Page 13 and 14: 13 BEING HEARD BY THE IR-4 PROJECT.
- Page 15 and 16: 15 ABSTRACTS FROM THE 7 TH CONFEREN
- Page 17: 17 HERBICIDE NAMES: COMMON, TRADE,
- Page 20 and 21: 20 INTEGRATING WEED CONTROL STRATEG
- Page 22 and 23: 22 GIANT HOGWEED ERADICATION IN PEN
- Page 26 and 27: 26 PRODUCER AND PRODUCTION IMPACTS
- Page 28 and 29: 28 A SIMPLE METHOD FOR CLEANING TUF
- Page 30 and 31: 30 EMERGENCE AND PERFORMANCE OF TWO
- Page 32 and 33: 32 CARFENTRAZONE AND QUINCLORAC FOR
- Page 34 and 35: 34 2006 NEWSS SUMMER WEED CONTEST R
- Page 36 and 37: 36 INVASIVE AQUATIC WEEDS IN NORTH
- Page 38 and 39: 38 AMMONIUM PELARGONATE AS A BIOHER
- Page 40 and 41: 40 TRINEXAPAC-ETHYL INFLUENCES EFFI
- Page 42 and 43: 42 Table 1. Insect feeding damage,
- Page 44 and 45: 44 WEED CONTROL WITH TOPRAMEZONE PR
- Page 46 and 47: 46 ROTARY HOE EFFICACY IN CORN: INF
- Page 48 and 49: 48 ALFALFA/GRASS FORAGE MIXTURES US
- Page 50 and 51: 50 CONTROL OF NEW WEED SPECIES IN T
- Page 52 and 53: 52 Table 1. Results of 2006 contain
- Page 54 and 55: 54 TOLERANCES OF ORNAMENTAL SHRUBS
- Page 56 and 57: 56 2006 WEED MANAGEMENT TRIALS IN C
- Page 58 and 59: 58 THE RESPONSE OF FIELD AND CONTAI
- Page 60 and 61: 60 THE EFFICACY AND CROP TOLERANCE
- Page 62 and 63: 62 Table 2. Plant quality ratings o
- Page 64 and 65: 64 EVALUATION OF PROLINE-LINKED PEN
- Page 66 and 67: 66 ANNUAL BLUEGRASS AND DOLLAR SPOT
- Page 68 and 69: 68 Table 1. Autumn 2005 versus spri
- Page 70 and 71: 70 A PRELIMINARY STUDY OF THE NON-N
- Page 72 and 73: 72 native species, covering and smo
24<br />
EFFECTS OF EMERGENCE PERIODICITY ON GROWTH AND FECUNDITY OF<br />
HORSEWEED. J.T. Dauer, The Pennsylvania State Univ., University Park, B.A. Scott<br />
and M.J. VanGessel, Univ. <strong>of</strong> Delaware, Georgetown, and D.A. Mortensen, The<br />
Pennsylvania State Univ., University Park.<br />
ABSTRACT<br />
The dispersal ability <strong>of</strong> winter annual and summer annual biotypes <strong>of</strong> horseweed<br />
(Conyza canadensis) was assessed along a 400 km latitudinal gradient between<br />
Pennsylvania and Delaware. Dispersal ability was defined by time <strong>of</strong> seed set, plant<br />
height and fecundity. Earlier seed set can result in greater opportunities for fall<br />
establishment and taller plants increase seed release height and impact dispersal<br />
distance. Greater fecundity increases <strong>the</strong> opportunities for populations to sample<br />
diverse environments and establish satellite populations. Sites were located in central<br />
and sou<strong>the</strong>astern Pennsylvania, and central and sou<strong>the</strong>rn Delaware with trials initiated<br />
in fall 2005 and replicated in fall 2006. Plots were arranged in a randomized complete<br />
block with four replications <strong>of</strong> two fall and two spring cohorts. Early and late cohorts<br />
were determined by germination before or after October 1st (fall) and April 15th (spring).<br />
Ten plants were randomly selected in each replicate, marked, and revisited biweekly to<br />
record plant height and percent flowering. Following seed release, final plant height<br />
was measured and capitula per plant were counted to estimate seed production. The<br />
late fall cohort was eliminated due to lack <strong>of</strong> overwintering success in Pennsylvania<br />
populations and data were averaged within a plot. In 2005-2006 seed set initiation<br />
progressed from south to north, however <strong>the</strong> next year, Pennsylvania populations set<br />
seed earlier than ei<strong>the</strong>r Delaware location. Location and treatment significantly affected<br />
final plant height (P
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