Laboratories Inc., New Bremen, OH). Weed seed survival assessment. In Freeville, NY only, locally sourced seeds of Powell amaranth ( Amaranthus powellii S. Wats.) and common lambsquarters ( Chenopodium album L.) were collected in Fall 2017 to assess seed
Haley Rylander, Anusuya Rangarajan, Ryan M. Maher, Mark G. Hutton, Nicholas W. Rowley, Margaret T. McGrath, and Zachary F. Sexton
Caitlin E. Splawski, Emilie E. Regnier, S. Kent Harrison, Mark A. Bennett, and James D. Metzger
. The most abundant and uniformly distributed weed was common lambsquarters ( Chenopodium album ) in 2011, and redroot pigweed ( Amaranthus retroflexus ) in 2012. Other weed species of secondary abundance included yellow foxtail ( Setaria pumila ), large
Dennis C. Odero, Jose V. Fernandez, and Nikol Havranek
control and 100% being crop death or complete weed control at 14 and 28 DAT. Prevalent weed species were common lambsquarters ( Chenopodium album L.), spiny amaranth ( Amaranthus spinosus L.), and fall panicum ( Panicum dichotomiflorum Michx.) at
Darren E. Robinson, Kristen McNaughton, and Nader Soltani
pigweed ( Amaranthus retroflexus L.), common ragweed ( Ambrosia artemisiifolia L.), common lambsquarters ( Chenopodium album L.), and eastern black nightshade ( Solanum ptycanthum Dun.). Napropamide, trifluralin, chlorthal dimethyl, and s
Orion P. Grimmer and John B. Masiunas
Winter-killed oats (Avena sativa) may have potential for use to suppress weeds in early seeded crops such as pea (Pisum sativum). Residue biomass and surface coverage are generally correlated with weed suppression. Oat residues also contain allelochemicals. Our objective was to determine if oat cultivars vary in residue production and allelopathy. Differences between oat cultivars were observed in residue production, and for effects on emergence of common lambsquarters (Chenopodium album) and shepherd's-purse (Capsella bursa-pastoris) in the greenhouse, and germination of pea and common lambsquarters in an infusion assay. Two of the oat cultivars producing the greatest biomass, `Blaze' (in the field) and `Classic' (in the greenhouse), interfered minimally with pea germination and were among the best cultivars in inhibiting common lambsquarters and shepherd's-purse. `Blaze' also greatly inhibited common lambsquarters germination in the infusion assay that measured allelopathy. Thus, `Blaze' and `Classic' possess suitable characteristics for use as a cover crop preceding peas.
Harry S. Agamalian
Initial weed competition in newly planted grapevines can delay vine development, resulting in reduced first harvest. The experiments were conducted over a three year period on three wine grape varieties: Chardonnay, Semillon, and Napa Gamay.
Dormant rooted plants were winter planted and subjected to soil applied preemergence herbicides. The experiment was conducted on a Greenfield sandy loam under sprinkler irrigation. Major weeds were little mallow (Malva pariflora), hairy nightshade (Solanum sarachoides), lambsquarters (Chenopodium album), and Russian thistle (Sasola iberica).
Vine growth was evaluated on cane weights, cane diameter, and cane length. Weed interference over the three year period resulted in 50% reduction in vine growth the first year. Yield data obtained from the third year resulted in significant differences between the weed free vines compared to the non-weeded treatments.
H. E. Hohlt, H. P. Wilson, and T. E. Hines
During 1989, clomazone (Command) was applied pretransplant or preemergence to transplanted and seeded watermelon (Citrullus lanatus, cv. Charleston Gray), respectively. Rates of 280, 414, and 560 g ai·ha-1 (0.50, 0.75, 1.0 pt/A) clomazone were applied to a Bojac sandy loam. Plots were rated for percentage weed control 21 DAT. Control of common lambsquarters [Chenopodium album (L.)], large crabgrass [Digitaria sanguinalis (L.) Scop.], and smooth pigweed (Amaranthus hybridus L.) increased with rate although smooth pigweed control was low. A significant phytotoxic injury characterized by bleaching and reduced growth occurred at all rates on melon transplants. No significant phytotoxicity occurred in seeded plots 35 DAT. Vine length (cm) was recorded 42 DAT. Vine length was reduced significantly at the 560 g·ha-1 rate in transplants. Vine length of seeded watermelons was not significantly affected.
G.D. Leroux, J. Douheret, M. Lanouette, and M. Martel
With growing public concern about environmental quality, farmers must turn to new plant protection alternatives that minimize the use of agrochemicals. Flaming has been practiced for several years as a means of weed control in noncropped areas (railroad, ditches, etc.), but its selectivity toward crops has yet to be defined. Experiments were conducted in the ICG-Propane laboratory at Laval Univ. to determine the temperature needed to kill weeds and the temperature that corn could tolerate. Four weed species were studied: Amaranthus retroflexus, Brassica kaber, Chenopodium album, and Setaria viridis and each species was tested at three growth stages: 0–2, 4–6, and >8 leaves. Corn tolerance was tested at four growth stages: coleoptile, 0–2, 4–6, >8 leaves. All plants were grown in the green-house and were submitted to different combinations of operation speeds and of propane pressures, giving 10 temperature intensities ranging from 110 to 390C. The response of each species was evaluated by measuring its height and dry biomass 2 weeks after treatment. The threshold temperature for corn was below 200C; above this temperature, significant corn injury occurred at all growth stages tested. The corn growth stages most tolerant to heat were coleoptile and >8 leaves. While the most sensitive was 4–6 leaves. All weeds tested were sensitive to heat at 0–2 leaf stage. Amaranthus retroflexus and Chenopodium album were controlled until six leaves with temperatures that were not harmful to corn. Weeds with more than eight leaves needed higher temperature, and control rarely reached 60%. Flaming could be a selective method of weed control if operated at a temperature of 170C. Selectivity can be increased by creating a growth differential between corn and weeds.
Orion P. Grimmer and John B. Masiunas
Winter-killed cover crops may protect the soil surface from erosion and reduce herbicide use in an early planted crop such as pea (Pisum sativum). Our objective was to determine the potential of winter-killed cover crops in a snap pea production system. White mustard (Brassica hirta) produced the most residue in the fall but retained only 37% of that residue into the spring. Barley (Hordeum vulgare) and oats (Avena sativa) produced less fall residue but had more residue and ground cover in the spring. Greater ground cover in the spring facilitated higher soil moisture, contributing to higher weed numbers and weight and lower pea yields for oat and barley compared with a bare ground treatment. White mustard had weed populations and pea yields similar to the bare ground treatment. Within the weed-free subplot, no differences in pea yields existed among cover crop treatments, indicating no direct interference with pea growth by the residues. In greenhouse experiments, field-grown oat and barley residue suppressed greater than 50% of the germination of common lambsquarters (Chenopodium album) and shepherd's-purse (Capsella bursapastoris), while in the field none of the cover crop provided better weed control than the fallow.
Robert E. Uhlig, George Bird, Robert J. Richardson, and Bernard H. Zandstra
A field study was conducted to evaluate fumigant alternatives for methyl bromide (MB). Iodomethane (IM), chloropicrin (CP), 1,3-dichloropropene (1,3-D), metham sodium (MS), and MB in various combinations were applied to a sandy soil field site in Sept. 2002. Some treatments were tarped. Plant injury, plant growth, fresh weight, and dry weight were evaluated for seven ornamental species: cushion spurge (Euphorbia polychroma), globe thistle (Echinops bannaticus ‘Blue Globe’), common lavender (Lavandula angustifolia ‘Hidcote Blue’), hosta (Hosta ‘Twilight PP14040’), silvermound artemisia (Artemisia schmidtiana ‘Silver Mound’), shasta daisy (Leucanthemum ×superbum ‘Snow Lady’), and thread leaf coreopsis (Coreopsis verticillata ‘Moonbeam’). Weed control was evaluated in Apr. 2003, July 2003, and May 2004. All treatments gave almost complete control of all annual weeds, except for IM 50% + CP 50% (200 lb/acre, tarped) and MS (75 gal/acre, 1:4 water, not tarped), which did not give adequate control of common chickweed (Stellaria media), mouseear cress (Arabidopsis thaliana), common lambsquarters (Chenopodium album), or common purslane (Portulaca oleracea). None of the treatments caused visual injury to any crop species. Treatments did not affect plant size in Nov. 2003. However, some treatments resulted in larger thread leaf coreopsis and silvermound artemisia plants in May 2004. There was no difference in dry weight at harvest between treatments for all species.