A Method for Assessing Herbicide Performance in Small Plot Experiments

Weed Science ◽  
1977 ◽  
Vol 25 (5) ◽  
pp. 386-389 ◽  
Author(s):  
A.S. Hamill ◽  
P.B. Marriage ◽  
G. Friesen
Keyword(s):  
Individual Species ◽  
Weed Species ◽  
Rating Systems ◽  
Small Areas ◽  
Retrieval Systems ◽  
Weed Cover ◽  
Weed Plants ◽  
Plot Area ◽  
Small Plot ◽  
Grass Weed

A method is described that provides an accurate and useful assessment of herbicide performance in small plot experiments. This method is an extension of previous rating systems and provides an assessment of the control of individual species through an estimation of the percentage that each contributes to the total broadleaf or grass weed cover on the whole plot area. It permits data collection on individual weed species but is less time-consuming than counting individual plants and it takes into account the size and vigor of individual weed plants as well as their relative abundance. Further, the system allows tabulation of data from across the entire plot rather than from small areas within the plot. The data can be readily entered into various computerized retrieval systems.

Mechanical Factors of Infl uence on Biological Effi ciency of Solanum Nigrum L.

2014 ◽  
Vol 1 (2) ◽  
pp. 20-23
Author(s):  
O. Ivashchenko ◽  
O. Ivashchenko
Keyword(s):  
Solanum Nigrum ◽  
Black Nightshade ◽  
Effi Ciency ◽  
Weed Plants ◽  
Sensitivity Level ◽  
Solanum Nigrum L ◽  
Small Plot ◽  
Mechanical Factors ◽  
The Moment ◽  
Working Out

Aim. Studying of black nightshade young plants’ response to the induced mechanical stresses. Methods. Researches conducted in small plot fi eld experiments. Results. Change of sensitivity level of Solanum nigrum L. plants depending on phases of their development at the moment of damage of elevated parts has been proven. Owing to loss of the surface capable to photosynthesis, there is an essential decrease in volumes of photosynthesis at plants of weed survived and their possibilities of ontogeny passage. The deep induced dis- stresses reduce biological effi ciency of plants, their ability to accumulate weight and to form seeds and even lead them to death. Conclusions. The defi ned principles of response of weed plants to the induced mechanical dis-stresses are can be used for working out and ecological receptions of crops protection from weeds.

The Effect of Piperonyl Butoxide and Adjuvants on Sulfonylurea Herbicide Activity

1996 ◽  
Vol 10 (1) ◽  
pp. 127-133 ◽  
Author(s):  
Chae Soon Kwon ◽  
Donald Penner
Keyword(s):  
Seed Oil ◽  
Oxidase Inhibitor ◽  
Piperonyl Butoxide ◽  
Mixed Function Oxidase ◽  
Sulfonylurea Herbicide ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Giant Foxtail ◽  
Herbicide Activity ◽  
Grass Weed

Greenhouse studies showed that the mixed function oxidase inhibitor, piperonyl butoxide (PBO), tank-mixed with the sulfonylurea herbicides, nicosulfuron, primisulfuron, and thifensulfuron, in the absence of effective adjuvants enhanced herbicide activity on both broadleaf and grass weed species. Effective adjuvants for nicosulfuron were K-3000 for common lambsquarters, Sylgard® 309 Surfactant for velvetleaf, K-2000 for barnyardgrass, and K-2000, K-3000, and Scoil® methylated seed oil for giant foxtail control. K-3000 and Sylgard 309 enhanced velvetleaf control with primisulfuron and thifensulfuron. The 28% urea and ammonium nitrate (UAN) was more effective as an adjuvant with thifensulfuron for velvetleaf than for common lambsquarters control. The enhancement of sulfonylurea herbicide activity with PBO was most apparent when other adjuvants were least effective.

The genus Salfacarus (Acari: Opilioacarida) in Madagascar

Zootaxa ◽  
2010 ◽  
Vol 2482 (1) ◽  
pp. 1 ◽  
Author(s):  
MA. MAGDALENA VÁZQUEZ G. ◽  
HANS KLOMPEN
Keyword(s):  
New Species ◽  
Type Species ◽  
Individual Species ◽  
Small Areas

The opilioacarid genus Salfacarus in Madagascar is revised, with description of four new species, S. antsirananensis, S. kirindiensis, S. mahafaliensis, and S. ranobensis, and a new delimitation for the type species, S. legendrei. Salfacarus is widespread in Madagascar but individual species appear restricted to relatively small areas. A key to the adults of Salfacarus in Madagascar is provided.

Combine Harvesting Affects Weed Seed Germination

1988 ◽  
Vol 2 (4) ◽  
pp. 499-504 ◽  
Author(s):  
Randall S. Currie ◽  
Thomas F. Peeper
Keyword(s):  
Seed Germination ◽  
Winter Wheat ◽  
Weed Seed ◽  
Weed Species ◽  
Hard Red Winter Wheat ◽  
Small Plot ◽  
Red Winter Wheat ◽  
Grain Bins ◽  
Better Than

Seed of three weed species collected from the grain bins of combines while standing hard red winter wheat was harvested germinated better than hand-harvested seed. Combine-harvested curly dock seed germinated from 4 to 24% more than hand-harvested seed. Curly dock seed harvested with a commercial-type combine germinated better than those harvested with a small-plot combine. Harvesting slimleaf lambsquarters and Venice mallow seed with a commercial-type combine also enhanced germination compared to hand-harvested seed.

scholarly journals Effects of Some Cover Crops on Light Extinction and Weed Coverage in Sunflower Field

2014 ◽  
Vol 47 (2) ◽  
pp. 29-40 ◽  
Author(s):  
S. Hassannejad ◽  
A.R. Mobli
Keyword(s):  
Extinction Coefficient ◽  
Cover Crops ◽  
Cover Crop ◽  
Agricultural Research ◽  
Block Design ◽  
Light Extinction ◽  
Research Station ◽  
Hairy Vetch ◽  
Weed Species ◽  
Weed Cover

Abstract In order to evaluate the effects of some cover crops on extinction coefficient and weed cover percentage in sunflower, a field experiment was conducted based on a randomized complete block design with nine treatments and three replicates at the Agricultural Research Station, Tabriz University of Iran, during growing season 2012-2013. Treatments were triticale, hairy vetch, rapeseed, triticale + hairy vetch, triticale + rapeseed, hairy vetch + rapeseed, application of trifluralin herbicide, and controls (weed infested and weed free without planting cover crop). Result indicated than once established, living mulches can rapidly occupy the open space between the rows of the main crop and use the light that would otherwise be available to weeds. In the all cover crops treatments, the light extinction coefficient was increased and weed cover percentage was reduced. Highest reduction in total weed species was observed in hairy vetch + rapeseed and triticale + rapeseed cover crop 61.92% and 61.43 %, respectively, compared to weed infested, so this treatment was better than trifluralin application. It concluded that cover crops could be considered as integrated strategies for weed sustainable management.

The Stability of Weed Seedling Population Models and Parameters in Eastern Nebraska Corn (Zea mays) and Soybean (Glycine max) Fields

Weed Science ◽  
1995 ◽  
Vol 43 (4) ◽  
pp. 604-611 ◽  
Author(s):  
Gregg A. Johnson ◽  
David A. Mortensen ◽  
Linda J. Young ◽  
Alex R. Martin
Keyword(s):  
Negative Binomial Distribution ◽  
Binomial Distribution ◽  
Negative Binomial ◽  
Sequential Sampling ◽  
Mean Value ◽  
Distribution Model ◽  
Ratio Test ◽  
Weed Species ◽  
Sampling Procedures ◽  
Grass Weed

Intensive field surveys were conducted in eastern Nebraska to determine the frequency distribution model and associated parameters of broadleaf and grass weed seedling populations. The negative binomial distribution consistently fit the data over time (1992 to 1993) and space (fields) for both the inter and intrarow broadleaf and grass weed seedling populations. The other distributions tested (Poisson with zeros, Neyman type A, logarithmic with zeros, and Poisson-binomial) did not fit the data as consistently as the negative binomial distribution. Associated with the negative binomial distribution is akparameter.kis a nonspatial aggregation parameter related to the variance at a given mean value. Thekparameter of the negative binomial distribution was consistent across weed density for individual weed species in a given field except for foxtail spp. populations. Stability of thekparameter across field sites was assessed using the likelihood ratio test There was no stable or commonkvalue across field sites and years for all weed species populations. The lack of stability inkacross field sites is of concern, because this parameter is used extensively in the development of parametric sequential sampling procedures. Becausekis not stable across field sites,kmust be estimated at the time of sampling. Understanding the variability in it is critical to the development of parametric sequential sampling strategies and understanding the dynamics of weed species in the field.

Transfer of resistance alleles from herbicide-resistant to susceptible grass weeds via pollen-mediated gene flow

2021 ◽  
pp. 1-51
Author(s):  
Amit J. Jhala ◽  
Hugh J. Beckie ◽  
Carol Mallory-Smith ◽  
Marie Jasieniuk ◽  
Roberto Busi ◽  
...  
Keyword(s):  
Gene Flow ◽  
Herbicide Resistance ◽  
Creeping Bentgrass ◽  
Agricultural Landscapes ◽  
Italian Ryegrass ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Wild Oats ◽  
Rigid Ryegrass ◽  
Grass Weed

Abstract The objective of this paper was to review the reproductive biology, herbicide-resistant (HR) biotypes, pollen-mediated gene flow (PMGF), and potential for transfer of alleles from HR to susceptible grass weeds including barnyardgrass, creeping bentgrass, Italian ryegrass, johnsongrass, rigid (annual) ryegrass, and wild oats. The widespread occurrence of HR grass weeds is at least partly due to PMGF, particularly in obligate outcrossing species such as rigid ryegrass. Creeping bentgrass, a wind-pollinated turfgrass species, can efficiently disseminate herbicide resistance alleles via PMGF and movement of seeds and stolons. The genus Agrostis contains about 200 species, many of which are sexually compatible and produce naturally occurring hybrids as well as producing hybrids with species in the genus Polypogon. The self-incompatibility, extremely high outcrossing rate, and wind pollination in Italian ryegrass clearly point to PMGF as a major mechanism by which herbicide resistance alleles can spread across agricultural landscapes, resulting in abundant genetic variation within populations and low genetic differentiation among populations. Italian ryegrass can readily hybridize with perennial ryegrass and rigid ryegrass due to their similarity in chromosome numbers (2n=14), resulting in interspecific gene exchange. Johnsongrass, barnyardgrass, and wild oats are self-pollinated species, so the potential for PMGF is relatively low and limited to short distances; however, seeds can easily shatter upon maturity before crop harvest, leading to wider dispersal. The occurrence of PMGF in reviewed grass weed species, even at a low rate is greater than that of spontaneous mutations conferring herbicide resistance in weeds and thus can contribute to the spread of herbicide resistance alleles. This review indicates that the transfer of herbicide resistance alleles occurs under field conditions at varying levels depending on the grass weed species.

Interference between hemp sesbania (Sesbania exaltata) and soybean (Glycine max) in response to irrigation and nitrogen

Weed Science ◽  
1997 ◽  
Vol 45 (1) ◽  
pp. 91-97 ◽  
Author(s):  
C. Andy King ◽  
Larry C. Purcell
Keyword(s):  
Field Experiments ◽  
Yield Loss ◽  
Individual Species ◽  
Weed Species ◽  
Soybean Yield ◽  
Sesbania Exaltata ◽  
Competition For Light ◽  
Hemp Sesbania ◽  
Chamber Studies ◽  
Growth Chamber Studies

Soybean yield loss from weed interference depends upon weed density and competitiveness of crop and weed species in response to environment. Soil water availability and nitrogen fertility were evaluated for their effect on competitiveness of individual species in field experiments. Early-season temperatures in 1995, which were cool compared to 1994, slowed hemp sesbania growth without affecting soybean growth. This resulted in negligible competition with soybean by hemp sesbania at densities of 3 or 6 plants m−2. In 1994, hemp sesbania grew above the soybean canopy, decreasing soybean light interception 29 to 68%, and reducing soybean yield 30 to 48%. Fertilizer nitrogen increased soybean competitiveness, as indicated by biomass production, only in irrigated plots with hemp sesbania at 3 m−2, but did not affect soybean yield. Apparently, competition for light is a primary cause of soybean yield loss from hemp sesbania infestations. In growth chamber studies, simulating temperatures from the field, hemp sesbania growth was stimulated more by warm temperatures than was soybean. Hemp sesbania and soybean dry weights increased 4.4- and 2.7-fold, respectively, at 30/20 C day/night temperatures compared to 25/15 C.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document