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 Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 3: Drivers of seed shatter

Weed Science ◽  
2021 ◽  
pp. 1-26
Author(s):  
Lauren M. Schwartz-Lazaro ◽  
Lovreet S. Shergill ◽  
Jeffrey A. Evans ◽  
Muthukumar V. Bagavathiannan ◽  
Shawn C. Beam ◽  
...  
Keyword(s):  
Management Practices ◽  
Plant Biomass ◽  
Weather Conditions ◽  
Field Studies ◽  
The United States ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Shattering ◽  
Early Season ◽  
Multiple Regions

Seed retention, and ultimately seed shatter, are extremely important for the efficacy of harvest weed seed control (HWSC) and likely influenced by various agro-ecological and environmental factors. Field studies investigated seed shattering phenology of 22 weed species across three soybean [Glycine max (L.) Merr.] producing regions in the US. We further evaluated the potential drivers of seed shatter in terms of weather conditions, growing degree days, and plant biomass. Based on the results, weather conditions had no consistent impact on weed seed shatter. However, there was a positive correlation between individual weed plant biomass and delayed weed-seed shattering rates during harvest. This work demonstrates that HWSC can potentially reduce weed seedbank inputs of plants that have escaped early season management practices and retained seed through harvest. However, smaller individuals of plants within the same population that shatter seed before harvest pose a risk of escaping early season management and HWSC.

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.

scholarly journals Molecular Basis for Resistance to Fluazifop-P-Butyl in Itchgrass (Rottboellia cochinchinensis) from Costa Rica

2016 ◽  
Vol 34 (1) ◽  
pp. 143-150 ◽  
Author(s):  
R. CASTILLO-MATAMOROS ◽  
A. BRENES-ANGULO ◽  
F. HERRERA-MURILLO ◽  
L. GÓMEZ ALPÍZAR.
Keyword(s):  
Costa Rica ◽  
Molecular Basis ◽  
Pcr Amplification ◽  
Costa Rican ◽  
Acetyl Coa Carboxylase ◽  
Annual Grass ◽  
San Jose ◽  
Weed Species ◽  
Rottboellia Cochinchinensis ◽  
Grass Weed

Rottboellia cochinchinensis is an annual grass weed species known as itchgrass, or "caminadora" in America´s Spanish speaking countries, and has become a major and troublesome weed in several crops. The application of fluazifop-P-butyl at recommended rates (125 g a.i. ha-1) was observed to be failing to control itchgrass in a field in San José, Upala county, Alajuela province, Costa Rica. Plants from the putative resistant R. cochinchinensis population survived fluazifop-P-butyl when treated with 250 g a.i. ha-1 (2X label rate) at the three- to four-leaf stage under greenhouse conditions. PCR amplification and sequencing of partial carboxyl transferase domain (CT) of the acetyl-CoA carboxylase (ACCase) gene were used to determine the molecular mechanism of resistance. A single non-synonymous point mutation from TGG (susceptible plants) to TGC (putative resistant plants) that leads to a Trp-2027-Cys substitution was found. This Trp-2027-Cys mutation is known to confer resistance to all aryloxyphenoxyproprionate (APP) herbicides to which fluazifop-P-butyl belongs. To the best of our knowledge, this is the first report of fluazifop-P-butyl resistance and a mutation at position 2027 for a Costa Rican R. cochinchinensis population.

Antagonism of Graminicide Activity on Annual Grass Species by Imazethapyr

1992 ◽  
Vol 6 (2) ◽  
pp. 333-338 ◽  
Author(s):  
Paul F. Myers ◽  
Harold D. Coble
Keyword(s):  
Weed Control ◽  
Field Experiments ◽  
Grass Species ◽  
Annual Grass ◽  
Antagonistic Interaction ◽  
Interaction Control ◽  
Grass Weed ◽  
Large Crabgrass

The interaction of imazethapyr and selected graminicides on annual grass control was studied in field experiments. Tank-mix combinations of imazethapyr with clethodim, fluazifop-P, quizalofop, or sethoxydim resulted in an antagonistic interaction. Control of large crabgrass, fall panicum, and broadleaf signalgrass by each graminicide decreased when tank-mixed with imazethapyr as compared with each graminicide applied alone. Sequential applications of imazethapyr, relative to each graminicide, successfully overcame the antagonism. Imazethapyr applied 5 d before or 1 d after each of the graminicides did not decrease grass weed control compared with each graminicide alone. Imazethapyr applied 3 or 1 d before, or the same day as the graminicides, generally decreased grass weed control.

scholarly journals Seed retention of winter annual grass weeds at winter wheat harvest maturity shows potential for harvest weed seed control

2019 ◽  
Vol 34 (2) ◽  
pp. 266-271 ◽  
Author(s):  
Neeta Soni ◽  
Scott J. Nissen ◽  
Philip Westra ◽  
Jason K. Norsworthy ◽  
Michael J. Walsh ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Great Plains ◽  
Downy Brome ◽  
Annual Grass ◽  
Weed Seed ◽  
Weed Species ◽  
Jointed Goatgrass ◽  
Seed Retention ◽  
Winter Annual ◽  
Feral Rye

AbstractDowny brome, feral rye, and jointed goatgrass are problematic winter annual grasses in central Great Plains winter wheat production. Integrated control strategies are needed to manage winter annual grasses and reduce selection pressure exerted on these weed populations by the limited herbicide options currently available. Harvest weed-seed control (HWSC) methods aim to remove or destroy weed seeds, thereby reducing seed-bank enrichment at crop harvest. An added advantage is the potential to reduce herbicide-resistant weed seeds that are more likely to be present at harvest, thereby providing a nonchemical resistance-management strategy. Our objective was to assess the potential for HWSC of winter annual grass weeds in winter wheat by measuring seed retention at harvest and destruction percentage in an impact mill. During 2015 and 2016, 40 wheat fields in eastern Colorado were sampled. Seed retention was quantified and compared per weed species by counting seed retained above the harvested fraction of the wheat upper canopy (15 cm and above), seed retained below 15 cm, and shattered seed on the soil surface at wheat harvest. A stand-mounted impact mill device was used to determine the percent seed destruction of grass weed species in processed wheat chaff. Averaged across both years, seed retention (±SE) was 75% ± 2.9%, 90% ± 1.7%, and 76% ± 4.3% for downy brome, feral rye, and jointed goatgrass, respectively. Seed retention was most variable for downy brome, because 59% of the samples had at least 75% seed retention, whereas the proportions for feral rye and jointed goatgrass samples with at least 75% seed retention were 93% and 70%, respectively. Weed seed destruction percentages were at least 98% for all three species. These results suggest HWSC could be implemented as an integrated strategy for winter annual grass management in central Great Plains winter wheat cropping systems.

scholarly journals Morphological Variations in Caryopses and Seedlings of Two Grass Species of the Genus Dactyloctenium Willd.

2017 ◽  
Vol 9 (2) ◽  
pp. 301-306
Author(s):  
Ajai Kumar SINGH ◽  
Ayush Kumar SINGH ◽  
Manish Kumar SRIVASTAVA
Keyword(s):  
Weed Management ◽  
Leaf Blade ◽  
Leaf Sheath ◽  
Grass Species ◽  
Weed Species ◽  
Base Surface ◽  
Morphological Variations ◽  
Dactyloctenium Aegyptium ◽  
Morphological Differences ◽  
Grass Weed

Dactyloctenium aegyptium (L.) Willd. and D. aristatum Link. are common grass weeds of cultivated fields in many crops. The two grass weed species growing under same habitat showed characteristic morphological differences of caryopses and seedlings. The identification of weeds at seedling stage may be useful in weed and environment management. Under the light microscopy, features like colour, base, surface, scutellum and hilum of caryopses showed differences between the studied species. D. aegyptium had dark brown caryopses colour, while D. aristatum had grey colour. The base of D. aegyptium was truncate, while D. aristatumhad obtuse base. Both species had rugose surface but in D. aegyptium surface undulations were closely spaced whereas in D. Aristatum it was widely spaced. Similarly seedlings were found distinct with respect to coleoptile shape and size, first leaf sheath surface and first leaf blade shape and surface. D. aegyptium had oblong coleoptile whereas it was obovate in D. aristatum. The leaf sheath and leaf blade were recorded glabrous and hairy in D. aegyptium and in D. aristatum respectively. Both species studied hereby, showed remarkable differentiations in their characters, thus indicating that the morphological attributes of caryopses and seedling can be exploited taxonomically and for crop and weed management.

Seed Longevity of 41 Weed Species Buried 17 Years in Eastern and Western Nebraska

Weed Science ◽  
1996 ◽  
Vol 44 (1) ◽  
pp. 74-86 ◽  
Author(s):  
Orvin C. Burnside ◽  
Robert G. Wilson ◽  
Sanford Weisberg ◽  
Kenneth G. Hubbard
Keyword(s):  
Great Plains ◽  
Weed Management ◽  
The United States ◽  
Decay Rates ◽  
Management Systems ◽  
Annual Grass ◽  
Weed Species ◽  
Seed Germinability ◽  
Soil Temperatures ◽  
Broadleaf Species

Seed of 41 economically important weed species of the Great Plains region of the United States were buried 20 cm deep in soil in eastern and western Nebraska in 1976. The 41 species consisted of 11 annual grass, 14 annual broadleaf, 4 biennial broadleaf, and 12 perennial broadleaf species. Weed seeds were exhumed annually for germination tests the first 9 yr, then after 12 and 17 yr. Germination percentages at the two burial locations averaged over 0, 1 to 4, 5 to 8, and 9 to 17 yr of burial were 57, 28, 9, and 4% for annual grass; 47, 26, 16, and 11 % for annual broadleaf; 52, 49, 44, and 30 % for biennial broadleaf; 36, 18, 13, and 8% for perennial broadleaf; and 47, 26, 16, and 10% for all 41 weed species, respectively. Biennial broadleaf weeds showed the greatest seed germination over years. Annual grass weeds showed less seed germinability over 17 yr of burial than annual broadleaf weeds and perennial broadleaf weed species were intermediate. Weed seed germinability in soil was greater in the reduced rainfall and more moderate soil temperatures of western Nebraska than in the greater rainfall and more fluctuating soil temperatures of eastern Nebraska. The greatest seed survival among the 41 weed species was shown by common mullein, which had 95% germination after 17 yr of burial in western Nebraska. Decay rates of individual weed species in soil will be of most value to weed scientists, agriculturalists, and modelers evaluating past or designing future weed management systems.

Weed Seed Banks Are More Dynamic in a Sod-Based, Than in a Conventional, Peanut–Cotton Rotation

Weed Science ◽  
2015 ◽  
Vol 63 (4) ◽  
pp. 877-887 ◽  
Author(s):  
Ramon G. Leon ◽  
David L. Wright ◽  
James J. Marois
Keyword(s):  
Crop Rotation ◽  
Seed Bank ◽  
Seed Banks ◽  
Community Diversity ◽  
Weed Seed ◽  
Weed Species ◽  
Perennial Crop ◽  
Seed Bank Dynamics ◽  
Weed Seeds ◽  
Grass Weed

Crop rotation promotes productivity, nutrient cycling, and effective pest management. However, in row-crop systems, rotation is frequently limited to two crops. Adding a third crop, especially a perennial crop, might increase crop-rotation benefits, but concerns about disruption of agricultural and ecological processes preclude grower adoption of a three-crop rotation. The objective of the present research was to determine whether weed seed banks differ between a sod-based rotation (bahiagrass–bahiagrass–peanut–cotton) and a conventional peanut–cotton rotation (peanut–cotton–cotton) and the importance of crop phase in weed seed-bank dynamics in a long-term experiment initiated in 1999 in Florida. Extractable (ESB) and germinable (GSB) seed banks were evaluated at the end of each crop phase in 2012 and 2013, and total weed seed or seedling number, Shannon-Weiner's diversity (H′), richness, and evenness were determined. ESB increased in H′ (36%), richness (29%), and total number of weed seeds (40%) for sod-based compared with conventional rotation, whereas GSB increased 32% in H′, 27% in richness, and 177% in total number of weed seedlings. Crop phase was a determinant factor in the differences between crop rotations. The first year of bahiagrass (B1) exhibited increases in weed seed and seedling number, H′, and richness and had the highest values observed in the sod-based rotation. These increases were transient, and in the second year of bahiagrass (B2), weed numbers and H′ decreased and reached levels equivalent to those in the conventional peanut–cotton rotation. The B1 phase increased the germinable fraction of the seed bank, compared with the other crop phases, but not the total number of weed seeds as determined by ESB. The increases in H′ and richness in bahiagrass phases were mainly due to grass weed species. However, these grass weed species were not associated with peanut and cotton phases of the sod-based rotation. The results of the present study demonstrated that including bahiagrass as a third crop in a peanut–cotton rotation could increase weed community diversity, mainly by favoring increases in richness and diversity, but the structure and characteristics of the rotation would prevent continuous increases in the weed seed bank that could affect the peanut and cotton phases.

Seed Retention of Grass Weeds at Wheat Harvest in the Pacific Northwest

Weed Science ◽  
2020 ◽  
pp. 1-32
Author(s):  
Carolina San Martín ◽  
Mark E Thorne ◽  
Jennifer A Gourlie ◽  
Drew J Lyon ◽  
Judit Barroso
Keyword(s):  
Pacific Northwest ◽  
Seed Production ◽  
Secale Cereale ◽  
Bromus Tectorum ◽  
Wheat Crop ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Shattering ◽  
Seed Retention ◽  
The Pacific

Abstract Harvest weed seed control (HWSC) may control problematic weeds by decreasing contributions to the weed seed bank. However, HWSC practices will not be effective if plants have shed a great part of their seeds before harvest, or if a low proportion of seed production is retained at a height that enables collection during harvest. The seed shattering pattern of several weed species was evaluated over three growing seasons to determine their potential to be controlled with HWSC in the Pacific Northwest (PNW). The studied weed species were downy brome (Bromus tectorum L.), feral rye (Secale cereale L.), Italian ryegrass [Lolium perenne ssp. multiflorum (Lam.) Husnot,], and rattail fescue [Vulpia myuros (L.) C.C. Gmel.]. Seed retention at harvest, seed production, and plant height differed among species, locations, and years. Environmental conditions influenced seed shattering patterns, particularly the time plants started to shatter seeds and the rate of the shattering. Agronomic factors such as herbicide use, inter-row space, or crop height/vigor also seemed to affect shattering patterns and seed production, but more specific studies must be conducted to determine their individual effects. Bromus tectorum, L. perenne ssp. multiflorum, and V. myuros had an average seed retention at harvest of less than 50%. In addition, the low seed retention height of V. myuros makes this species a poor candidate for HWSC. Secale cereale had average seed retention at harvest greater than 50% and seed retention height was greater than 30 cm. The variability of seed retention in different species will make the efficacy of HWSC practices species and environment dependent in PNW winter wheat cropping systems. Harvesting the wheat crop as early as possible will be crucial to the success of HWSC.

Response of Teff, Barnyardgrass, and Broadleaf Weeds to Postemergence Herbicides

2014 ◽  
Vol 28 (2) ◽  
pp. 371-376
Author(s):  
O. Steven Norberg ◽  
Joel Felix
Keyword(s):  
Weed Control ◽  
Warm Season ◽  
Field Studies ◽  
The United States ◽  
Production Costs ◽  
Grain Production ◽  
Annual Grass ◽  
Food Grain ◽  
Postemergence Herbicides ◽  
Grass Weed

Teff is a warm-season C4 annual grass crop grown for forage and food grain that has recently increased in production in parts of the United States. Hay from teff is well suited for livestock, especially horses. The objective of this study was to evaluate teff and weed response to selected herbicides in field studies conducted at the Malheur Experiment Station, Ontario, OR in 2009 and 2010. Herbicides were applied POST when teff was at the four-leaf stage. Broadleaf weed control at 21 d after treatment was greater than 91% across herbicide treatments. Only the premix of 2.5 g ai ha−1florasulam + 99 g ae ha−1fluroxypyr + 15 g ai ha−1pyroxsulam provided acceptable control of barnyardgrass. Due primarily to barnyardgrass competition, teff treated with a premix of 2.5 g ha−1florasulam + 99 g ha−1fluroxypyr + 15 g ha−1pyroxsulam produced 7,200 kg ha−1of teff hay compared with 4,800 kg ha−1of teff hay for 2,4-D and dicamba and 4,200 kg ha−1teff hay when no herbicides were used. Teff grain production was greater with 2.5 g ha−1florasulam + 99 g ha−1fluroxypyr + 15 g ha−1pyroxsulam compared with any of the other treatments. The use of a premix of florasulam + fluroxypyr + pyroxsulam would improve broadleaf and grass weed control in ‘Tiffany' and ‘Dessie' teff varieties, improve hay and grain yield, and reduce production costs.

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