Relationship between Temperature and Heat Duration on Large Crabgrass (Digitaria sanguinalis), Virginia Buttonweed (Diodia virginiana), and Cock's-Comb Kyllinga (Kyllinga squamulata) Seed Mortality

2012 ◽  
Vol 26 (4) ◽  
pp. 800-806 ◽  
Author(s):  
Jared A. Hoyle ◽  
J. Scott McElroy
Keyword(s):  
Exposure Time ◽  
Thermal Exposure ◽  
Exposure Period ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Mortality ◽  
Thermal Death ◽  
Thermal Death Point ◽  
Virginia Buttonweed ◽  
Large Crabgrass

Thermal heat has been utilized for nonselective weed control methods. These methods are highly variable in application and efficacy. One effective weed–seed-control determining factor is achieving the thermal death point of targeted weed seeds. The thermal death point varies by weed species, temperature, and exposure time. Our objective was to determine the thermal death point of large crabgrass, cock's-comb kyllinga, and Virginia buttonweed at short thermal exposure periods. Studies conducted utilized 5 and 20 s exposure periods for incremental range, 60 to 250 C temperatures. Sigmoid regression curves were used to predict weed seed mortality by temperature and exposure time. A significant interaction between exposure period and temperature occurred for each weed species. Weed species increased in susceptibility to 20 s thermal heat as follows: Virginia buttonweed < cock's-comb kyllinga < large crabgrass. Increasing thermal exposure time from 5 to 20 s reduced thermal temperature by 21 C to achieve 50% mortality for large crabgrass and by 10 C for cock's-comb kyllinga. Virginia buttonweed achieved 50% mortality at 99 C for 5 and 20 s exposure periods. These data indicate that at least 50% weed seed mortality can be achieved at 99 and 103 C for 20 and 5 s exposure periods, respectively, for these weed species.

Weed Seed Contamination of Cotton Gin Trash

2009 ◽  
Vol 23 (4) ◽  
pp. 574-580 ◽  
Author(s):  
Jason K. Norsworthy ◽  
Kenneth L. Smith ◽  
Lawrence E. Steckel ◽  
Clifford H. Koger
Keyword(s):  
Surface Layer ◽  
Palmer Amaranth ◽  
Weed Seed ◽  
Weed Species ◽  
Cattle Feed ◽  
Material Development ◽  
Crop Fields ◽  
Viable Seeds ◽  
Prickly Sida ◽  
Large Crabgrass

Cotton gins in Arkansas, western Tennessee, and western Mississippi were sampled for weed seed contamination of gin trash in fall 2007. A total of 473 samples were collected, with 453 samples from Arkansas. The objectives of this research were to determine the weed species most frequently found in gin trash and determine what means gin operators are using to dispose of gin trash. There were 25 weed species found in the gin trash samples—11 grass and 14 broadleaf weeds. Grass and broadleaf weeds were present in 41.4 and 8.5% of the samples, respectively. The most frequently found species were large crabgrass (19.0%), barnyardgrass (14.0%), goosegrass (12.9%), red sprangletop (8.2%) and Palmer amaranth (4.2%). Viable seeds of barnyardgrass, large crabgrass, Palmer amaranth, and prickly sida were present in the surface layer (0- to 25-cm depth) of gin trash piles after 1 yr of composting. Viable Palmer amaranth seeds were present in the surface layer of gin trash piles after 2 yr of composting, but no germinable seeds were found deeper than 25 cm following 1 yr of composting. Gin trash disposal involved application of the material to crop fields during the fall or winter months; composting followed by application of the compost as mulch or a soil amendment to gardens, flower beds, or crop fields; use as cattle feed; and coverage for landfills to reduce erosion and encourage growth of vegetation. Because of the demonstrated potential for weed seed dispersal via gin trash, including composted material, development of technologies to ensure disposal of a gin-trash product free of viable weed seed are justified.

Nitrogen Fertilizer and Crop Residue Effects on Seed Mortality and Germination of Eight Annual Weed Species

Weed Science ◽  
2007 ◽  
Vol 55 (2) ◽  
pp. 123-128 ◽  
Author(s):  
Adam S. Davis
Keyword(s):  
Corn Stover ◽  
C:N Ratio ◽  
N Fertilizer ◽  
N Availability ◽  
Soil N ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Mortality ◽  
Giant Ragweed ◽  
Microbial Predation

Weed seed persistence in the soil seedbank is central to weed population dynamics; however, limited knowledge of mechanisms regulating seed survival in soil remains an obstacle to developing seed-bank management practices. Weed seeds are rich in carbon and nitrogen, and therefore may represent an important nutritional resource to soil microbes. The objective of this study was to test the hypothesis that weed seed mortality due to microbial predation is limited by soil inorganic N availability and soil C:N ratio. A factorial of N fertilizer rate (0, 14, and 28 mg N kg soil−1) and corn stover addition rate (0 and 3,000 mg stover kg soil−1) was applied to bioassay units containing Illinois field soil (silt loam, 3.8% organic carbon) and seeds of one of eight annual weed species common to Illinois field crops: giant foxtail, green foxtail, yellow foxtail, wooly cupgrass, giant ragweed, redroot pigweed, velvetleaf, and Venice mallow. Seeds were incubated for 2 mo, after which they were recovered from the soil and tested for viability. Only three of the eight species, velvetleaf, giant ragweed, and wooly cupgrass, responded to the experimental treatments. Velvetleaf seed mortality was 40% lower in the corn stover–amended treatment than in the unamended treatment. Both giant ragweed and wooly cupgrass showed a more complex interaction between N fertilizer and corn stover treatments. Path analysis supported the hypothesis that the influence of soil N on seed mortality in velvetleaf was because of the direct effect of soil N on microbial predation of velvetleaf seeds, whereas for giant ragweed and wooly cupgrass, the effect on seed mortality appeared to be mediated through soil N effects on germination. Mechanisms underlying soil N fertility effects on weed seed mortality appear to be species-specific. Future investigations of this phenomenon should include quantitative measures of seed coat composition and quality.

scholarly journals Soil Texture and Planting Depth Affect Large Crabgrass (Digitaria sanguinalis), Virginia buttonweed (Diodia virginiana), and Cock’s-comb Kyllinga (Kyllinga squamulata) Emergence

HortScience ◽  
2013 ◽  
Vol 48 (5) ◽  
pp. 633-636 ◽  
Author(s):  
Jared A. Hoyle ◽  
J. Scott McElroy ◽  
Elizabeth A. Guertal
Keyword(s):  
Soil Texture ◽  
Soil Surface ◽  
Loamy Sand ◽  
Clay Loam ◽  
Weed Species ◽  
Planting Depth ◽  
Virginia Buttonweed ◽  
Water Holding ◽  
Weed Emergence ◽  
Large Crabgrass

Greenhouse studies were conducted to explore soil texture and planting depth effects on emergence of large crabgrass, Virginia buttonweed, and cock’s-comb kyllinga. Soil textures examined were sand, loamy sand, and clay loam with planting depths of 0, 0.5, 1, 2, 4, 6, and 8 cm. Percent emergence was standardized relative to surface emergence to allow comparisons among tested weed species. The three-way interaction of weed species, planting depth, and soil texture was never significant for emergence. Significant interactions occurred between weed species and soil texture, weed species and planting depth, and soil texture and planting depth. For all weed species and soil textures, emergence decreased as planting depth increased with the greatest percent emergence at the soil surface. The planting depth at which weed emergence was decreased 50% [relative to surface emergence (D50)] was predicted by regression analysis. Large crabgrass emerged from deepest depths (8 cm) followed by Virginia buttonweed (6 cm) and cock’s-comb kyllinga (2 cm). Large crabgrass, Virginia buttonweed, and cock’s-comb kyllinga D50 occurred at 3.9, 1.1, and 0.8 cm, respectively. Sand, loamy sand, and clay loam D50 occurred at 0.9, 2.3, and 1.9 cm, respectively, with D50 higher in the soils with greater water-holding capacity.

Response of Four Summer Annual Weed Species to Mowing Frequency and Height

2013 ◽  
Vol 27 (4) ◽  
pp. 798-802 ◽  
Author(s):  
RaeLynn A. Butler ◽  
Sylvie M. Brouder ◽  
William G. Johnson ◽  
Kevin D. Gibson
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Management Practices ◽  
Dry Weight ◽  
Weed Seed ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Giant Ragweed ◽  
Total Dry Weight ◽  
Large Crabgrass

Greenhouse experiments were conducted in 2011 to evaluate the effect of mowing frequency and mowing height on four summer annual weed species (large crabgrass, barnyardgrass, giant ragweed, and common lambsquarters). Plants were clipped at three heights (5, 10, or 20 cm) and at two frequencies (single clipping or repeated clippings at the same height) to simulate mowing. A nonclipped control was also grown for each species. When clipped once, large crabgrass, barnyardgrass, and giant ragweed produced at least 90% of the total dry weight (DW) of the nonclipped plants, and common lambsquarters produced at least 75%. A single cut was generally not sufficient to prevent weed seed production or kill any of the weeds in this study. Repeated clipping reduced large crabgrass, giant ragweed, and common lambsquarters reproductive DW to 46, 27, and 10% respectively, of the nonclipped control. Barnyardgrass plants that were repeatedly clipped produced between 0 and 8% of the seed DW of nonclipped plants, depending on clipping height. Repeated clipping reduced weed total DW to below 40% for all species compared to nonclipped plants. Our results suggest that, unless combined with other weed management practices, repeated mowing may be necessary to limit the growth and seed production of these weed species.

Weed Control with Liquid Carbon Dioxide in Established Turfgrass

2014 ◽  
Vol 28 (3) ◽  
pp. 560-568
Author(s):  
Denis J. Mahoney ◽  
Matthew D. Jeffries ◽  
Travis W. Gannon
Keyword(s):  
Carbon Dioxide ◽  
Weed Control ◽  
Exposure Time ◽  
White Clover ◽  
Kentucky Bluegrass ◽  
Life Cycles ◽  
Liquid Carbon ◽  
Liquid Carbon Dioxide ◽  
Virginia Buttonweed ◽  
Large Crabgrass

In recent years, increasing implementation of biological, cultural, and mechanical weed-control methods is desired; however, many of these techniques are not viable in established turfgrass systems. The use of freezing or frost for weed control has previously been researched; however, is not well elucidated. Field and greenhouse experiments were conducted to evaluate liquid carbon dioxide (LCD) for weed control in established turfgrass systems. LCD was applied with handheld prototypes that were modified to reduce the amount of LCD required for weed control. Common annual and perennial turfgrass weeds included common chickweed, corn speedwell, goosegrass, large crabgrass, smooth crabgrass, Virginia buttonweed, and white clover. Turfgrass tolerance was evaluated on the following species: hybrid bermudagrass, Kentucky bluegrass, tall fescue, and zoysiagrass. The final modification allowed for lower output (0.5 kg LCD min−1) when compared with the initial prototype (3 kg LCD min−1). In general, weed control increased as LCD increased. When comparing weed species life cycles, annuals were controlled more than perennials (P < 0.0001) at 14 and 28 d after treatment (DAT). Further, exposure time affected control as white clover, Virginia buttonweed, and large crabgrass control was greater (18, 14, 15%, respectively) from the longer exposure time (30 vs. 15 s), although equivalent amounts of LCD (30 kg m−2) were applied. These data also suggest that plant maturity affects control, as large crabgrass control in one- to two- and three- to four-leaf stages (> 90%) was greater than in the one- to two-tiller stage (< 70%). Turfgrass injury at 7 DAT was unacceptable (> 30%) on all species, but declined to 0% by 28 DAT. These data suggest that LCD has the potential to provide an alternative for weed control of select species where synthetic herbicides are not allowed or desired.

Influence of chaff and chaff lines on weed seed survival and seedling emergence in Australian cropping systems

2020 ◽  
pp. 1-22
Author(s):  
Michael J. Walsh ◽  
Annie E. Rayner ◽  
Annie Rutledge ◽  
John C. Broster
Keyword(s):  
Cropping Systems ◽  
Seedling Emergence ◽  
Field Studies ◽  
Wild Oat ◽  
Weed Seed ◽  
Weed Species ◽  
Environment Effect ◽  
Seed Survival ◽  
Cropping Seasons ◽  
Rigid Ryegrass

Abstract Chaff lining and chaff tramlining are harvest weed seed control (HWSC) systems that involve the concentration of weed seed containing chaff material into narrow (20 to 30 cm) rows between or on the harvester wheel tracks during harvest. These lines of chaff are left intact in the fields through subsequent cropping seasons in the assumption that the chaff environment is unfavourable for weed seed survival. The chaff row environment effect on weed seed survival was examined in field studies, while chaff response studies determined the influence of increasing amounts of chaff on weed seedling emergence. The objectives of these studies were to determine 1) the influence of chaff lines on the summer-autumn seed survival of selected weed species; and 2) the influence of chaff type and amount on rigid ryegrass seedling emergence. There was frequently no difference (P>0.05) in survival of seed of four weed species (rigid ryegrass, wild oat, annual sowthistle and turnip weed) when these seed were placed beneath or beside chaff lines. There was one instance where wild oat seed survival was increased (P<0.05) when seed were placed beneath compared to beside a chaff line. The pot studies determined that increasing amounts of chaff consistently resulted in decreasing numbers of rigid ryegrass seedlings emerging through chaff material. The suppression of emergence broadly followed a linear relationship where there was approximately a 2.0% reduction in emergence with every 1.0 t ha-1 increase in chaff material. This relationship was consistent across wheat, barley, canola and lupin chaff types, indicating that the physical presence of the chaff was more important than chaff type. These studies indicated that chaff lines may not affect the over summer-autumn survival of the contained weed seeds but the subsequent emergence of weed seedlings will be restricted by high amounts of chaff (>40 t ha-1).

Absorption, Translocation, and Metabolism of14C-Glufosinate in Glufosinate-Resistant Corn, Goosegrass (Eleusine indica), Large Crabgrass (Digitaria sanguinalis), and Sicklepod (Senna obtusifolia)

Weed Science ◽  
2009 ◽  
Vol 57 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Wesley J. Everman ◽  
Cassandra R. Mayhew ◽  
James D. Burton ◽  
Alan C. York ◽  
John W. Wilcut
Keyword(s):  
Weed Species ◽  
Digitaria Sanguinalis ◽  
Eleusine Indica ◽  
Leaf Stage ◽  
Senna Obtusifolia ◽  
Harvest Timing ◽  
Treated Leaf ◽  
Harvest Intervals ◽  
Corn Plants ◽  
Large Crabgrass

Greenhouse studies were conducted to evaluate14C-glufosinate absorption, translocation, and metabolism in glufosinate-resistant corn, goosegrass, large crabgrass, and sicklepod. Glufosinate-resistant corn plants were treated at the four-leaf stage, whereas goosegrass, large crabgrass, and sicklepod were treated at 5, 7.5, and 10 cm, respectively. All plants were harvested at 1, 6, 24, 48, and 72 h after treatment (HAT). Absorption was less than 20% at all harvest intervals for glufosinate-resistant corn, whereas absorption in goosegrass and large crabgrass increased from approximately 20% 1 HAT to 50 and 76%, respectively, 72 HAT. Absorption of14C-glufosinate was greater than 90% 24 HAT in sicklepod. Significant levels of translocation were observed in glufosinate-resistant corn, with14C-glufosinate translocated to the region above the treated leaf and the roots up to 41 and 27%, respectively. No significant translocation was detected in any of the weed species at any harvest timing. Metabolites of14C-glufosinate were detected in glufosinate-resistant corn and all weed species. Seventy percent of14C was attributed to glufosinate metabolites 72 HAT in large crabgrass. Less metabolism was observed for sicklepod, goosegrass, and glufosinate-resistant corn, with metabolites composing less than 45% of detectable radioactivity 72 HAT.

scholarly journals Influence of crop rotation, tillage, and management inputs on weed seed production

Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 175-183 ◽  
Author(s):  
George O. Kegode ◽  
Frank Forcella ◽  
Sharon Clay
Keyword(s):  
Seed Production ◽  
Crop Rotation ◽  
Crop Production ◽  
Conservation Tillage ◽  
Farming Systems ◽  
Crop Rotations ◽  
Weed Seed ◽  
Weed Species ◽  
Weed Seeds ◽  
Ridge Tillage

Approaches to crop production that successfully reduce weed seed production can benefit farming systems by reducing management inputs and costs. A 5-yr rotation study was conducted in order to determine the effects that interactions between crop rotation, tillage, and amount of herbicide and fertilizer (management inputs) have on annual grass and broad-leaved weed seed production and fecundity. There were 10 crop rotation and tillage system combinations and three levels of management inputs (high, medium, and low). Green and yellow foxtail were the major weed species, and together they yielded between 76 and 93% of collected weed seeds. From 1990 to 1994, average grass weed seed productions were 7.3 by 103, 3.7 by 1036.1 by 103and 5.7 by 103seeds m−-2, whereas average broad-leaved weed seed productions were 0.4 by 103, 0.4 by 103, 1.4 by 103, and 0.4 by 103seeds m−-2in crop rotations using conventional tillage (moldboard plow), conservation tillage, no tillage, and ridge tillage, respectively. Crop rotations using conventional or ridge tillage consistently produced more grass and broad-leaved weed seeds, especially in low-input plots. There was little difference in weed seed production among input levels for crop rotations using conservation tillage. Comparing rotations that began and ended with a corn crop revealed that by increasing crop diversity within a rotation while simultaneously reducing the amount of tillage, significantly fewer grass and broad-leaved weed seeds were produced. Among the rotations, grass and broad-leaved weed fecundity were highly variable, but fecundity declined from 1990 to 1994 within each rotation, with a concomitant increase in grass and broad-leaved weed density over the same period. Crop rotation in combination with reduced tillage is an effective way of limiting grass and broad-leaved weed seed production, regardless of the level of management input applied.

Detection of Compositional Fluctuations in High Temperature Exposed Waspaloy

2001 ◽  
Vol 699 ◽  
Author(s):  
Xiaodong Zou ◽  
Tariq Makram ◽  
Rosario A. Gerhardt
Keyword(s):  
Exposure Time ◽  
Structural Integrity ◽  
Thermal Exposure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gamma Prime ◽  
Distribution Shape ◽  
The Matrix ◽  
Quantitative Stereology ◽  
Nickel Base

AbstractWaspaloy is a nickel base super-alloy used in aircraft engines. When this alloy is placed in service, it is subjected to long term exposure at high temperatures, which can cause the reinforcing gamma prime precipitate population to fluctuate and thus affect its structural integrity. The population fluctuates as a result of coarsening, dissolution or re-precipitation. Samples exposed to 1200° F for times ranging from 0 to 12626 hours were characterized using impedance spectroscopy, microhardness measurements, x-ray diffraction and quantitative stereology. Two important parameters were derived from the impedance measurements: (1) the imaginary admittance peak magnitude (Ymax) and (2) the associated relaxation frequency (fmax). As the distribution, shape and size of the precipitates change with exposure time, these parameters were also found to vary. In addition to the changes in precipitate geometry, lattice constant changes detected by analyzing x-ray diffraction data suggest that there are compositional shifts in the matrix as well as the gamma prime precipitates. Furthermore, the preferred orientation of the precipitates can also be seen to change with exposure time. These changes in composition, size and shape as a function of thermal exposure time are accompanied by changes in the volume fractions of primary and secondary gamma prime particles present. Using effective medium models, it is possible to predict that the measured properties are related to the gamma prime population. The grain boundary carbides do not appear to play any role at the conditions presented.

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