Emergence characteristics of four annual weed species

Weed Science ◽  
1999 ◽  
Vol 47 (5) ◽  
pp. 578-584 ◽  
Author(s):  
Robert G. Hartzler ◽  
Douglas D. Buhler ◽  
David E. Stoltenberg
Keyword(s):  
Initial Time ◽  
Grass Species ◽  
First Year ◽  
Weed Species ◽  
Emergence Period ◽  
Seed Sources ◽  
Amaranthus Rudis ◽  
Eriochloa Villosa ◽  
Broadleaf Species ◽  
Emergence Date

Emergence characteristics, including initial time of emergence, magnitude of emergence, and mean time of emergence, ofAmaranthus rudisSauer,Setaria faberiHerrm.,Eriochloa villosa(Thunb.) Kunth, andAbutilon theophrastiMedik. were studied in central Iowa during the first 3 yr following burial of seed collected and buried in the fall of 1994 or 1995. Although the initial emergence date varied among years, the emergence sequence among species was consistent.Eriochloa villosaand A.theophrastiwere the first species to emerge, with initial emergence occurring between April 28 and May 10. Initial emergence dates for these species were the same, except for 1995 whenA. theophrastiemerged 4 d prior toE. villosa. Amaranthus rudiswas the last species to emerge, with initial emergence ranging from 5 to 25 d afterA. theophrasti.First-year emergence in 1995 was 8% forA. theophrasti, 7% for A.rudis, 41% forE. villosa, and 33% forS. faberi, based on the number of buried seed. Proportional emergence during the first year following burial in 1996 was similar to 1995 forA. theophrastiandS. faberi, but greater emergence was observed in 1996 forE. villosaandA. rudis.During the 3 yr of both studies, cumulative emergence of the two grass species (43 to 71%) was higher than for the broadleaf species (13 to 35%). A high percentage of the total annual emergence ofE. villosaoccurred within the first 2 wk of initial emergence, whereas a high percentage ofA. rudisemergence occurred late in its emergence period. Emergence characteristics of the four species were consistent among years and seed sources.

Effect of Ensiling and Rumen Digestion by Cattle on Weed Seed Viability

Weed Science ◽  
1991 ◽  
Vol 39 (1) ◽  
pp. 104-108 ◽  
Author(s):  
Robert E. Blackshaw ◽  
Lyle M. Rode
Keyword(s):  
Time Course ◽  
Seed Viability ◽  
Grass Species ◽  
Lag Phase ◽  
Rapid Decline ◽  
Weed Species ◽  
Embryo Viability ◽  
Seed Survival ◽  
Gradual Process ◽  
Broadleaf Species

Studies were conducted to determine the effect of ensiling and/or rumen digestion by cattle on the germination and viability of several common weed species. Seed survival of grass species subjected to ensiling and/or rumen digestion tended to be less than that of broadleaf species. Downy brome, foxtail barley, and barnyardgrass were nonviable after either ensiling for 8 weeks or rumen digestion for 24 h. Some green foxtail (17%) and wild oats (0 to 88%) seeds survived digestion in the rumen but were killed by the ensiling process. Varying percentages of seeds of kochia, redroot pigweed, common lambsquarters, wild buckwheat, round-leaved mallow, and field pennycress remained viable after ensiling (3 to 30%), rumen digestion (15 to 98%), and ensiling plus rumen digestion (2 to 19%). A time course study of rumen digestion indicated that loss of seed viability often was not a gradual process. With some species, there was an initial lag phase while degradation of the protective seed coat likely occurred, followed by a rapid decline in embryo viability. The diet fed to livestock appeared to affect viability losses caused by rumen digestion. Estimates of seed survival with varying rates of passage through the rumen due to differing ratios of grain to forage in the diet are presented.

Seedbank and Emerged Annual Weed Populations in Cornfields (Zea mays) in Colorado

1998 ◽  
Vol 12 (2) ◽  
pp. 243-247 ◽  
Author(s):  
Edward E. Schweizer ◽  
Philip Westra ◽  
Donald W. Lybecker
Keyword(s):  
Zea Mays ◽  
Grass Species ◽  
Single Plant ◽  
Annual Grass ◽  
Weed Species ◽  
Plant Populations ◽  
Redroot Pigweed ◽  
Broadleaf Species

Fifty irrigated cornfields in five eastern Colorado counties were sampled for their seedbanks and annual weed seedlings and mature populations between 1988 and 1992. Fourteen annual broadleaf species and seven annual grass species were identified in the 50 seedbanks sampled after the fields were tilled in the fall. Redroot pigweed and a mixture of green and yellow foxtail were the weed species encountered most, occurring in 90 and 54% of the fields, respectively. The single-plant populations of broadleaf and grass species in June and September were similar to those observed in the seedbanks. The number of weed species as seeds in the seedbank, June seedlings, and September plants per field ranged from zero to five grass species and zero to eight broadleaf species.

scholarly journals Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 1: broadleaf species

Weed Science ◽  
2020 ◽  
pp. 1-29
Author(s):  
Lauren M. Schwartz-Lazaro ◽  
Lovreet S. Shergill ◽  
Jeffrey A. Evans ◽  
Muthukumar V. Bagavathiannan ◽  
Shawn C. Beam ◽  
...  
Keyword(s):  
The United States ◽  
Ambrosia Artemisiifolia ◽  
Retention Rates ◽  
Weed Species ◽  
Physiological Maturity ◽  
Seed Retention ◽  
Northern Latitudes ◽  
Multiple Regions ◽  
Broadleaf Species ◽  
Crop Maturity

Abstract Potential effectiveness of harvest weed seed control (HWSC) systems depends upon seed shatter of the target weed species at crop maturity, enabling its collection and processing at crop harvest. However, seed retention likely is influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed shatter phenology in thirteen economically important broadleaf weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to four weeks after physiological maturity at multiple sites spread across fourteen states in the southern, northern, and mid-Atlantic U.S. Greater proportions of seeds were retained by weeds in southern latitudes and shatter rate increased at northern latitudes. Amaranthus species seed shatter was low (0 to 2%), whereas shatter varied widely in common ragweed (Ambrosia artemisiifolia L.) (2 to 90%) over the weeks following soybean physiological maturity. Overall, the broadleaf species studied shattered less than ten percent of their seeds by soybean harvest. Our results suggest that some of the broadleaf species with greater seed retention rates in the weeks following soybean physiological maturity may be good candidates for HWSC.

Herbicide Effects on Weed Control and Shoot Growth of Young Apple (Malus sylvestris) and Peach (Prunus persica) Trees

1994 ◽  
Vol 8 (4) ◽  
pp. 840-848 ◽  
Author(s):  
Chester L. Foy ◽  
Susan B. Harrison ◽  
Harold L. Witt
Keyword(s):  
Shoot Growth ◽  
Field Experiments ◽  
Prunus Persica ◽  
Weed Species ◽  
Apple Trees ◽  
Herbicide Treatments ◽  
One Year ◽  
Broadleaf Species ◽  
Old Trees ◽  
Peach Trees

Field experiments were conducted at two locations in Virginia to evaluate the following herbicides: alachlor, diphenamid, diuron, metolachlor, napropamide, norflurazon, oryzalin, oxyfluorfen, paraquat, pendimethalin, and simazine. One experiment involved newly-transplanted apple trees; the others, three in apple and one in peach trees, involved one-year-old trees. Treatments were applied in the spring (mid-April to early-May). Control of annual weed species was excellent with several treatments. A broader spectrum of weeds was controlled in several instances when the preemergence herbicides were used in combinations. Perennial species, particularly broadleaf species and johnsongrass, were released when annual species were suppressed by the herbicides. A rye cover crop in nontreated plots suppressed the growth of weeds. New shoot growth of newly-transplanted apple trees was increased with 3 of 20 herbicide treatments and scion circumference was increased with 11 of 20 herbicide treatments compared to the nontreated control. Growth of one-year-old apple trees was not affected. Scion circumference of one-year-old peach trees was increased with 25 of 33 herbicide treatments.

A Survey of Glyphosate-Resistant Waterhemp (Amaranthus rudis) in Missouri Soybean Fields and Prediction of Glyphosate Resistance in Future Waterhemp Populations Based on In-Field Observations and Management Practices

2013 ◽  
Vol 27 (4) ◽  
pp. 656-663 ◽  
Author(s):  
Kristin K. Rosenbaum ◽  
Kevin W. Bradley
Keyword(s):  
Crop Production ◽  
Management Practices ◽  
Production Systems ◽  
Glyphosate Resistance ◽  
Continuous Cropping ◽  
Field Observations ◽  
Weed Species ◽  
Herbicide Treatment ◽  
Amaranthus Rudis

A survey of soybean fields containing waterhemp infestations was conducted just prior to harvest in 2008 and 2009 to determine the frequency and distribution of glyphosate-resistant waterhemp in Missouri, and to determine if there are any in-field parameters that may serve as indicators of glyphosate resistance in this species in future crop production systems. Glyphosate resistance was confirmed in 99 out of 144, or 69%, of the total waterhemp populations sampled, which occurred in 41 counties of Missouri. Populations of glyphosate-resistant waterhemp were more likely to occur in fields with no other weed species present at the end of the season, continuous cropping of soybean, exclusive use of glyphosate for several consecutive seasons, and waterhemp plants showing obvious signs of surviving herbicide treatment compared to fields characterized with glyphosate-susceptible waterhemp. Therefore, it is suggested that these four site parameters, and certain combinations of these parameters, serve as predictors of glyphosate resistance in future waterhemp populations.

scholarly journals Weeds Interference in Pequi Plants

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
D.A. MARTINS ◽  
A. JAKELAITIS ◽  
A.C. COSTA ◽  
G.M.A. ALMEIDA ◽  
R.O. SILVA FILHO
Keyword(s):  
Additional Treatment ◽  
Grass Species ◽  
Photochemical Quenching ◽  
Forage Grass ◽  
Effective Quantum Yield ◽  
Weed Species ◽  
Juvenile Period ◽  
Ps Ii ◽  
Physiological Variables ◽  
Fruit Species

ABSTRACT: Pequi plants are native fruit species of the Cerrado and is at risk of extinction due to the destruction of native vegetation and the extraction of their fruits. Because this species has a long juvenile period, it becomes susceptible to the interference of weeds, mainly forage grass. This research aimed to evaluate the effects of forage grass species coexisting with small seedlings. The treatments, arranged in a factorial scheme, consisted of three weed species(Melinis minutiflora, Paspalum notatumandUrochloa decumbens)coexisting in four densities (1, 2, 3, and 4 plants per pot) with pequi plants. As an additional treatment a pequi plant was cultivated free of coexistence. The physiological variables photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E) Ci/Ca relation, the effective quantum yield of PS II, transport rate of electrons and non-photochemical quenching, and growth variables: height (PH), Leaf area (LA) and dry matter (DM) were affected by weed coexistence.U. decumbenspromoted greater intensity interference with pequi plants. The degree of interference was greater with increasing density of weeds, with linear decreasing behavior for the variables A, gs, E, PH, LA, MD, stem diameter and number of leaves of pequi plants.

scholarly journals Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 2: grass species

Weed Science ◽  
2020 ◽  
pp. 1-19
Author(s):  
Lauren M. Schwartz-Lazaro ◽  
Lovreet S. Shergill ◽  
Jeffery A. Evans ◽  
Muthukumar V. Bagavathiannan ◽  
Shawn C. Beam ◽  
...  
Keyword(s):  
The United States ◽  
Grass Species ◽  
Annual Grass ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Shattering ◽  
Physiological Maturity ◽  
Rate Of Progression ◽  
Multiple Regions ◽  
Grass Weed

Abstract Seed shatter is an important weediness trait on which the efficacy of harvest weed seed control (HWSC) depends. The level of seed shatter in a species is likely influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed shatter of eight economically important grass weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to four weeks after maturity at multiple sites spread across eleven states in the southern, northern, and mid-Atlantic U.S. From soybean maturity to four weeks after maturity, cumulative percent seed shatter was lowest in the southern U.S. regions and increased as the states moved further north. At soybean maturity, the percent of seed shatter ranged from 1 to 70%. That range had shifted to 5 to 100% (mean: 42%) by 25 days after soybean maturity. There were considerable differences in seed shatter onset and rate of progression between sites and years in some species that could impact their susceptibility to HWSC. Our results suggest that many summer annual grass species are likely not ideal candidates for HWSC, although HWSC could substantially reduce their seed output at during certain years.

scholarly journals Relative Susceptibility Among Alternative Host Species Prevalent in the Great Plains to Wheat streak mosaic virus

Plant Disease ◽  
2012 ◽  
Vol 96 (8) ◽  
pp. 1185-1192 ◽  
Author(s):  
D. Ito ◽  
Z. Miller ◽  
F. Menalled ◽  
M. Moffet ◽  
M. Burrows
Keyword(s):  
Mosaic Virus ◽  
Great Plains ◽  
Transmission Efficiency ◽  
Wheat Streak Mosaic Virus ◽  
Viral Reservoir ◽  
Grass Species ◽  
Mechanical Transmission ◽  
Weed Species ◽  
Crop Species ◽  
Jointed Goatgrass

Wild grasses, crops, and grassy weeds are known to host Wheat streak mosaic virus (WSMV) and its vector, the wheat curl mite (WCM). Their relative importance as a source of WSMV was evaluated. A survey of small-grain fields throughout Montana was conducted between 2008 and 2009. Cheatgrass was the most prevalent grassy weed and the most frequent viral host, with 6% infection by WSMV in 2008 (n = 125) and 15% in 2009 (n = 358). By mechanically inoculating plants with WSMV in the greenhouse, the highest susceptibility was found in rye brome (52.1%), jointed goatgrass (80.9%), and wild oat (53.9%. Quackgrass, not previously reported as a host, was susceptible to WSMV (12.7%). Mite transmission efficiency from susceptible grass species was lower than from wheat, and grass species must be a host for both WSMV and the WCM to serve as a virus source. WCM transmission was more efficient than mechanical transmission. Overall, results indicate that grass species can serve as a viral reservoir, regional variation in a weed species' susceptibility to WSMV cannot explain geographic variation in epidemic intensity, and crop species and closely related weeds (e.g., jointed goatgrass) remain the best reservoirs for both WSMV and the WCM.

scholarly journals Floristic diversity of the soil weed seedbank in boro rice fields: in situ and ex situ evaluation

2018 ◽  
Vol 16 (3) ◽  
pp. 396-402
Author(s):  
Fahmida Akter ◽  
Mahfuza Begum ◽  
Md. Abdus Salam
Keyword(s):  
Shannon Index ◽  
Ex Situ ◽  
Floristic Diversity ◽  
Weed Species ◽  
Importance Value ◽  
Emergence Period ◽  
Research Fields ◽  
Weed Survey ◽  
Boro Rice

This study was conducted at the research fields of Agronomy Field Laboratory and in the net house of Department of Agronomy, Bangladesh Agricultural University, Mymensingh. The objective of this study was to compare the in situ and ex situ floristic diversity of soil weed seedbank in boro rice. The soil weed seedbank status was observed through weed survey at research fields and seed germination method in the net house. Five fields were selected randomly with four replications. Soil samples were collected to a depth up to 15 cm and placed in plastic pots in the net house. Weed seedlings that emerged were identified, counted and removed at 30 day intervals throughout the four months emergence period. At the same time, weed survey was done using a 0.25 m–2 quadrate. Diversity was computed by the Shannon index (H’). Under in situ condition, 31 weed species belonging to 15 families germinated and 33 weed species belonging to 17 families germinated under ex situ condition. The family Cyperaceae had the highest species richness under both in situ and ex situ conditions. The five most dominant weed species under in situ condition based on importance value were Eleocharis atroperpurea > Cyperus difformis > Echinochloa crusgalli > Monochoria vaginalis > Lindernia antipoda whereas, under ex situ condition, two new weed species, Fimbristylis miliacea and Echinochloa colonum were observed in the dominant list instead of Monochoria vaginalis and Lindernia antipoda having slightly different rank and order. The ex situ density was 2721 plants m–2, approximately four times higher than the 700 plants m–2 observed under in situ situation and similarly ex situ condition had higher Shannon Index (H’) value (H’=2.412) indicating greater diversity than in situ (H’=2.211) condition. The information obtained from the study would help determine the infestation potential of identified species, which could lead to improved management strategies. J. Bangladesh Agril. Univ. 16(3): 396–402, December 2018

Use of water by six grass species. 1. Dry-matter yields and response to irrigation

1979 ◽  
Vol 93 (1) ◽  
pp. 13-24 ◽  
Author(s):  
E. A. Garwood ◽  
K. C. Tyson ◽  
J. Sinclair
Keyword(s):  
Perennial Ryegrass ◽  
Tall Fescue ◽  
Field Capacity ◽  
Italian Ryegrass ◽  
Grass Species ◽  
First Year ◽  
Full Irrigation ◽  
Yield And Quality ◽  
Second Year

SUMMARYThe yield and quality of herbage produced by six grasses (perennial ryegrass, cocksfoot, timothy, rough-stalked meadow grass, tall fescue and Italian ryegrass) were examined both without irrigation and under two irrigation regimes. Water was applied according to the potential soil water deficit (potential SWD): the soil was either partially returned to field capacity (FC) after each cut or fully returned to FC whenever the potential SWD reached 25 mm. The swards were cut either at 3 (C3) or 6 (C6) week intervals over a 2 year period.Partial irrigation increased yields by 12–14% in the first year and by 36–58% in the second. Full irrigation produced little more growth than partial irrigation in the first year (maximum SWD, 188 mm) but increased yield by 78–93% in the second, very dry, year (maximum SWD, 311 mm). Under treatment C3 response per unit of water applied was similar with both partial and full irrigation, but under C6 the response was greater with partial (2·86 kg D.M./m3) than with full irrigation (1·79 kg D.M./m3).There were marked differences between the species in their ability to grow under drought conditions in the second year of the experiment. Without irrigation, roughstalked meadow grass and Italian ryegrass did not survive the drought. The performance of tall fescue was markedly superior to both perennial ryegrass and cocksfoot in these conditions. Of the surviving grasses timothy made least growth.

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