scholarly journals Modeling emergence of sterile oat (Avena sterilis ssp. ludoviciana) under semiarid conditions

Weed Science ◽  
2021 ◽  
Vol 69 (3) ◽  
pp. 341-352
Author(s):  
Carlos Sousa-Ortega ◽  
Aritz Royo-Esnal ◽  
Iñigo Loureiro ◽  
Ana I. Marí ◽  
Juan A. Lezáun ◽  
...  
Keyword(s):  
Weed Species ◽  
Avena Sterilis ◽  
Prediction Ability ◽  
Average Percentage ◽  
Growing Seasons ◽  
Ceiling Temperature ◽  
Special Concern ◽  
Cardinal Temperatures ◽  
Base Water Potential ◽  
Semiarid Conditions

AbstractWinter wild oat [Avena sterilis ssp. ludoviciana (Durieu) Gillet & Magne; referred to as A. sterilis here] is one of the major weed species of the Avena genus, given its high competitive ability to infest cereal crops worldwide, with special concern in Spain. A nine-location field experiment was established across Spain where a total of 400 A. sterilis seeds per location were sowed in four replicates in autumn 2016 to monitor the emergence during two growing seasons in dryland conditions. The data were used to test the prediction ability of previously published thermal (TT) and hydrothermal time (HTT) models and to develop new models, if required. Overall, the average percentage of emergence was 30% during the first season and 21% during the second season. In both seasons, the main emergence flush occurred between November and February. According to the phenological stage, A. sterilis achieved the tillering earlier in southern sites, between November 25 and the end of December, compared with northern sites, where this stage was reached at the end of January. The newly developed model described the emergence with precision, using three cardinal temperatures to estimate the TT. The three cardinal points were established at −1.0, 5.8, and 18.0 C for base (Tb), optimum (To), and ceiling temperature (Tc), while the base water potential (Ψb) was established at −0.2 MPa for the HTT estimation. This study contributes to improving prediction of the emergence of A. sterilis and provides knowledge for decision support systems (DSS) for the control of this weed.

scholarly journals Predicting Seedling Emergence of Three Canarygrass (Phalaris) Species under Semi-Arid Conditions Using Parametric and Non-Parametric Models

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 893
Author(s):  
Carlos Sousa-Ortega ◽  
Aritz Royo-Esnal ◽  
José María Urbano
Keyword(s):  
Field Experiments ◽  
Seedling Emergence ◽  
Parametric Models ◽  
Base Temperature ◽  
Weed Species ◽  
Emergence Period ◽  
Growing Seasons ◽  
Ceiling Temperature ◽  
Base Water Potential ◽  
Non Parametric

The Phalaris genus includes annual weed species such as short-spiked canarygrass (Phalaris brachystachys Link.), little-seed canarygrass (Phalaris minor Retz.) and hood canarygrass (Phalaris paradoxa L.), which are especially problematic in Spain; as such, there is a need to develop models to predict the timing of their emergence. Field experiments were conducted at two different locations during two (2006/07 and 2007/08) and three (from 2005/06 to 2007/08) growing seasons. In both locations, 500 seeds of each Phalaris species were sown each growing season, simulating rain-fed cereal field conditions. In addition, the models were validated with three, four and eight independent experiments for P. brachystachys, P. minor and P. paradoxa, respectively. The emergence period of the three Phalaris species lasted between 31 and 48 days after sowing (DAS), showing two main flushes. The three cardinal points for parametric and non-parametric models were established to be between −1 °C and 1 °C for base temperature, between 9.8 °C and 11.8 °C for optimal temperature and between 21.2 °C and 23.4 °C for ceiling temperature; base water potential was estimated to be between −1 and −1.1 MPa. Both parametric and non-parametric models obtained similar results and were successfully validated in 12 out of 15 independent experiments.

Determination of Cardinal Temperatures of Flax-leaf Alyssum (Alyssum linifolium) in Response to Salinity, pH, and Drought Stress

Weed Science ◽  
2018 ◽  
Vol 66 (4) ◽  
pp. 470-476 ◽  
Author(s):  
Ahmadreza Mobli ◽  
Ali Ghanbari ◽  
Mehdi Rastgoo
Keyword(s):  
Germination Rate ◽  
Farming Systems ◽  
Quadratic Polynomial ◽  
Polynomial Model ◽  
Weed Species ◽  
Wide Range ◽  
Species Specific ◽  
Cardinal Temperatures ◽  
Different Levels

AbstractFlax-leaf alyssum (Alyssum linifoliumSteph. ex. Willd.) is a winter weed species in irrigated and dryland farming systems of Iran. Experiments were conducted to compare the cardinal temperatures ofA. linifoliumat different levels of drought, salt concentration, and pH. In all experiments, the dent-like model showed a better fit than the quadratic polynomial model.Alyssum linifoliumproduced the highest germination rates at pH 7 and a temperature of 20C in nonstress treatment. Minimum, optimum, and ceiling temperatures in the dent-like model were 4.1 (upper=26.8, lower=10.0) and 35C, and in the quadratic polynomial model were 3.3, 19.1, and 35.0C, respectively. At increased salinity and drought potential levels, the minimum temperature increased, while optimum and ceiling temperatures decreased. Seeds could germinate at up to 20 dS m−1and −1 MPa, respectively, but germination rate and percentage significantly decreased. The seeds of this weed germinated across a wide range of pH values (4≤pH≥8), but the temperature range at which seeds could germinate was reduced. These data serve as guidelines for species-specific propagation protocols and agricultural decision support systems.

Seasonal changes in forage nutritive value of common weeds encountered in Missouri pastures

2019 ◽  
Vol 34 (2) ◽  
pp. 164-171
Author(s):  
Gatlin Bunton ◽  
Zach Trower ◽  
Craig Roberts ◽  
Kevin W. Bradley
Keyword(s):  
Tall Fescue ◽  
Crude Protein ◽  
Nutritive Value ◽  
Late Summer ◽  
Growing Season ◽  
Quality Parameter ◽  
Neutral Detergent Fiber ◽  
Weed Species ◽  
Growing Seasons

AbstractDuring the 2015, 2016, and 2017 growing seasons, weed and weed-free mixed tall fescue and legume forage samples were harvested from 29 pastures throughout Missouri for investigation of the nutritive value of 20 common pasture weed species throughout the season. At certain times during the growing season, many broadleaf weed species had greater nutritive values for a given quality parameter as compared with the available weed-free, mixed tall fescue and legume forage harvested from the same location. There were no significant differences in crude protein concentration between the weed-free forage and many weeds throughout the growing season. However, crude protein content of common burdock, common cocklebur, common ragweed, dandelion, horsenettle, and lanceleaf ragweed was greater than that of the corresponding forage sample at multiple collection periods. The digestible neutral detergent fiber (dNDF) content of all broadleaf weeds except lanceleaf ragweed was significantly lower than that of the weed-free forage at all collection periods. Conversely, large crabgrass had significantly greater digestible neutral detergent fiber levels than did the mixed tall fescue forage at all sampling dates. Dandelion and spiny amaranth had greater in vitro true digestibility (IVTD) content than did the forage for the entire growing season. Three perennial weeds—horsenettle, vervains, and late boneset—did not differ in IVTD levels as compared with the mixed tall fescue and legume forage at any collection date. For most summer annual weeds, the trend was toward greater digestibility earlier in the season, with a gradual decline and often lower IVTD by the late summer or early fall. The results of this study will enable producers to make more informed management decisions about the potential benefit or detriment a weed may provide to the overall nutritive value of the pasture system.

Relationships between soil, forage, and grazing parameter effects on weed incidence in Missouri pastures

2019 ◽  
Vol 34 (3) ◽  
pp. 408-415
Author(s):  
Gatlin Bunton ◽  
Zachary Trower ◽  
Kevin W. Bradley
Keyword(s):  
Soil Ph ◽  
Tall Fescue ◽  
Perennial Grass ◽  
Weed Species ◽  
Perennial Weed ◽  
Soil P ◽  
Weed Density ◽  
Growing Seasons ◽  
Unit Increase ◽  
Grass Weed

AbstractDuring the 2015, 2016, and 2017 growing seasons, a survey of 63 pastures in Missouri was conducted to determine the effects of selected soil and forage parameters on the density of common annual, biennial, and perennial weed species. Permanent sampling areas were established in each pasture at a frequency of one representative 20-m2 area per 4 ha of pasture, and weed species and density in each area were determined at 14-d intervals for a period from mid-April until late September. The parameters evaluated included soil pH, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), sulfur (S), zinc (Zn), manganese (Mn), and copper (Cu) concentrations, as well as tall fescue density, forage groundcover density, and stocking rate. An increase of 1 unit in soil pH was associated with 146 fewer weeds per hectare, the largest reduction in weed density in response to any soil parameter. Increased soil pH was associated with the greatest reduction in perennial grass weed density, along with an average reduction of 1,410 brush weeds per hectare for each 1-unit increase in soil pH. Common ragweed, a widespread weed of pastures, could be reduced by 3,056 weeds ha−1 when soil pH was 1 unit greater. A 1-ppm increase in soil P was correlated with a decrease of 206 biennial broadleaf weeds per hectare. Perennial broadleaf weed density was reduced in soils with greater concentrations of P, K, and Ca. Additionally, for every 1% increase of tall fescue and forage groundcover, there was a decrease of 18 and 38 perennial broadleaf weeds per hectare. The results from this research indicate that the density of many common weed species can be reduced with higher soil pH and adjustments to soil macro- and micronutrient concentrations, especially P.

Morphological and genetic factors influencing the response of weed species to herbicides

1978 ◽  
Vol 56 (12) ◽  
pp. 1466-1471 ◽  
Author(s):  
D. J. Tomkins ◽  
W. F. Grant
Keyword(s):  
Genetic Factors ◽  
Life Form ◽  
Basic Chromosome Number ◽  
Nuclear Volume ◽  
Weed Species ◽  
Interphase Chromosome ◽  
Basic Chromosome ◽  
Growing Seasons ◽  
Resistant Species ◽  
Factors Influencing

The survival of 75 weed species after exposure to herbicides (auxin and nonselective) was monitored over three growing seasons. Each species was classified as resistant, susceptible, or intermediate in response. Polyploids were consistently more resistant to both types of herbicides. In addition, average somatic (but not basic) chromosome number was significantly higher in species resistant to nonselective herbicides than in susceptible ones. The averages of both nuclear volume and interphase chromosome volume were greater in species resistant to auxins than in susceptible ones, although the results were not statistically significant at the 5% probability level. There was a significantly greater proportion of monocots than dicots among the auxin-resistant species, but there was no correlation between life-form and response to either group of herbicides.

scholarly journals Long term ground cover options for apple orchards

2005 ◽  
Vol 58 ◽  
pp. 164-168 ◽  
Author(s):  
K.C. Harrington ◽  
M.J. Hartley ◽  
A. Rahman ◽  
T.K. James
Keyword(s):  
Ground Cover ◽  
Apple Orchard ◽  
Festuca Rubra ◽  
Weed Species ◽  
Red Fescue ◽  
Growing Seasons ◽  
Control Option ◽  
Better Than ◽  
Tree Production

A trial was established in a new Hawkes Bay apple orchard in September 1998 to determine how well various ground cover treatments could control weed competition and influence tree production Results are presented after six growing seasons Competition during the first growing season resulted in effects on the trees that were still measurable many years later Dichondra (Dichondra micrantha) gave a good ground cover for the first few years but slowly regressed to hardtocontrol weed species The red fescue (Festuca rubra) plots survived better than dichondra although also had problems Bark mulch needed continual assistance from herbicides Some of the treatments were modified after two growing seasons to investigate establishing ground covers after initially using bark mulches Results are discussed in terms of using any form of ground cover as a weed control option in orchards looking at advantages disadvantages and effects on the weed flora

scholarly journals Distribution and Survival of Pseudomonas sp. on Italian Ryegrass and Curly Dock in Georgia

Plant Disease ◽  
2014 ◽  
Vol 98 (5) ◽  
pp. 660-666 ◽  
Author(s):  
Bhabesh Dutta ◽  
Ronald D. Gitaitis ◽  
Theodore M. Webster ◽  
Hunt Sanders ◽  
Samuel Smith ◽  
...  
Keyword(s):  
Lolium Multiflorum ◽  
Italian Ryegrass ◽  
Time Interval ◽  
Bacterial Disease ◽  
Pseudomonas Sp ◽  
Weed Species ◽  
Rumex Crispus ◽  
Growing Seasons ◽  
Onion Seed ◽  
Polymerase Chain

Yellow bud, caused by Pseudomonas sp., is an emerging bacterial disease of onion. A polymerase chain reaction assay based on the coronafacate ligase (cfl) and HrpZ genes was used to detect initial suspected bacteria on weeds. Growth on an agar medium, ability to cause a hypersensitive response in tobacco, pathogenicity on onion, and sequence analysis of 16S ribosomal RNA and cfl genes were used to confirm the identity of Pseudomonas sp. recovered from 10 asymptomatic weed species in the Vidalia onion-growing zone (VOZ) of Georgia. Among the weeds identified as epiphytic hosts for Pseudomonas sp., Italian ryegrass (Lolium multiflorum) and curly dock (Rumex crispus) were prominent because ≥73% of the samples from five sample sites were positive for the bacterium. These weeds are commonly found throughout Georgia and, thus, were selected to assess their role in yellow bud epidemiology. Samples of the two weed species were collected from sites along the perimeter of and within the VOZ (n = 5 sites) during late June, August, and September 2012 and 2013, which represented the time interval between onion growing seasons. Samples (n = 10/weed species/site) were collected and processed for bacterial detection as described above. In June (2012 and 2013), Pseudomonas sp. was detected from Italian ryegrass and curly dock in 100 and 40% of the sample sites, respectively. During the months of August and September (2012), the bacterium was recovered from Italian ryegrass in 60 and 10% of the sample sites, respectively; whereas, in August (2013), Pseudomonas sp. was recovered from 40% of the sample sites. However, the bacterium was not recovered from any of the sites in September (2013). In contrast, during August and September (2012), Pseudomonas sp. was recovered from curly dock in 20 and 80% of the sample sites, respectively. Similarly, in August and September (2013), the bacterium was detected from 40 and 100% of the sample sites, respectively. These data demonstrated that the Pseudomonas sp. responsible for yellow bud can survive as an epiphyte on Italian ryegrass and curly dock between onion crops. Furthermore, using artificially infested onion seed, we demonstrated that Pseudomonas sp. can be transmitted through contaminated seed.

scholarly journals Physiochemical Characterization and Field Assessment of Lettuce Chlorosis Virus

Plant Disease ◽  
1998 ◽  
Vol 82 (11) ◽  
pp. 1248-1252 ◽  
Author(s):  
Jennifer McLain ◽  
Steven Castle ◽  
Gerald Holmes ◽  
Rebecca Creamer
Keyword(s):  
Molecular Weight ◽  
Enzyme Linked Immunosorbent Assay ◽  
Weed Species ◽  
Imperial Valley ◽  
Western Blots ◽  
Growing Seasons ◽  
Transmission Electron ◽  
Field Assessment ◽  
Lettuce Infectious Yellows Virus ◽  
Field Plots

Lettuce chlorosis virus (LCV) was purified and partially characterized, and polyclonal antisera were produced and used to assess disease in the field. The antisera reliably detected LCV by indirect enzyme-linked immunosorbent assay (ELISA) in Nicotiana benthamiana. In Western blots, the LCV antisera distinguished between LCV and lettuce infectious yellows virus (LIYV)-infected plants. LCV particle lengths in partially purified preparations, as observed by transmission electron microscopy, were variable, with the majority between 750 and 950 nm long. A single, high molecular weight dsRNA and several lower molecular weight dsRNAs were isolated from LCV-infected N. benthamiana. A single RNA isolated from purified virion preparations was estimated to be 8,625 nucleotides long and was suspected to be the genomic RNA of LCV. LCV was present in experimental field plots in Holtville, California, during the lettuce growing seasons of 1995 to 1997. The percentage of symptomatic plants and yield of lettuce heads treated with insecticide, as well as dsRNA and ELISA reactions for the plots, are reported. A dsRNA consistent in size with LCV was isolated from four weed species in the Imperial Valley of California.

scholarly journals Germination Patterns in Naturally Chilled and Nonchilled Seeds of Fierce Thornapple (Datura Ferox) and Velvetleaf (Abutilon Theophrasti)

Weed Science ◽  
2009 ◽  
Vol 57 (2) ◽  
pp. 155-162 ◽  
Author(s):  
José Dorado ◽  
César Fernández-Quintanilla ◽  
Andrea C. Grundy
Keyword(s):  
Good Description ◽  
Natural Populations ◽  
Hydrothermal Time ◽  
Weed Species ◽  
Central Spain ◽  
Natural Conditions ◽  
Embryo Dormancy ◽  
Dry Conditions ◽  
The Mean ◽  
Base Water Potential

Seeds from natural populations of fierce thornapple and velvetleaf collected in a corn-growing area in central Spain were incubated at a range of constant temperatures and water potentials to model the progress of germination on the basis of the accumulation of hydrothermal time. Previous to the germination tests, the seeds were treated in two different ways: (1) dark storage under dry conditions (nonchilled seeds), and (2) burying in the original soil at 10-cm depth during 2 mo in winter (naturally chilled seeds). The results indicated different mechanisms inhibiting germination in both weed species. Whereas fierce thornapple displayed some type of embryo dormancy, the lack of germination in velvetleaf appeared to be entirely due to the seed coat. On the other hand, significant differences between nonchilled and naturally chilled seeds in fierce thornapple were observed, mainly due to the decrease in the mean base water potential of the 50th percentile in the latter, which indicated a loss of dormancy by exposure of the seeds to natural conditions. Hydrothermal time appears to be a good description of the germination patterns in both weed species, but in the case of fierce thornapple, only for naturally chilled seeds. Thus, the development of the hydrothermal model in fierce thornapple raises some questions for consideration concerning the influence of the type of seeds (conditions of storage, pretreatments of the seeds before germination tests) on its germination capacity.

scholarly journals Weed Control in Sunflower (Helianthus annuus L.) with Soil-applied Herbicides Affected by a Prolonged and Limited rainfall

Poljoprivreda ◽  
2021 ◽  
Vol 27 (2) ◽  
pp. 3-14
Author(s):  
Zvonko Pacanoski ◽  
◽  
Arben Mehmeti ◽  
Keyword(s):  
Weed Control ◽  
Chenopodium Album ◽  
Field Trials ◽  
Early Spring ◽  
Amaranthus Retroflexus ◽  
Soil Conditions ◽  
Weed Species ◽  
Polygonum Aviculare ◽  
Growing Seasons ◽  
Solanum Nigrum L

The field trials were carried out in the Bitola and Titov Veles regions during two sunflower growing seasons (2018 and 2019) to estimate a weed control in sunflower with the soil‒applied herbicides, influenced by a prolonged and limited rainfall. Polygonum aviculare L., Solanum nigrum L., Chenopodium album L., Amaranthus retroflexus L., Portulaca oleracea L., and Echinochloa crus-galli (L.) P. Beauv. were the most dominant weeds in both regions. The efficacy of PRE-em herbicides varied among the weed species, treatments, periods of efficacy estimation, regions, and years. The overall performances of the PRE-em herbicides were correlated with weather and soil conditions. The inconsistent weather patterns between the two years of the study likely influenced the weed control. All weeds in 2018 in the Bitola region were poorly controlled (<77% and <62%, 28 and 56 days after application, respectively) due to a higher amount of rainfall (57 mm) during the 10 days of the 1st decade after herbicide application. The herbicide efficacy has only produced a marginal control of weeds in 2019 in the Titov Veles region as well (<68% and <59%, 28 and 56 days after application, respectively), due to the drought conditions observed in this region in early spring and in mid-spring. A PREem application followed by a heavy rainfall resulted in a sunflower injury in the Bitola region in 2018, ranging from 9 to 28% across the PRE-em treatments seven days after emergence. The injuries by oxyfluorfen and dimethenamid-P were more serious (24 and 28%, respectively). The sunflower achene yields for each treatment in both regions generally reflected an overall weed control and crop injury.

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