Weeds of winter wheat fields in Saskatchewan – survey results from 1985 and 1986

Non-Peer Reviewe

Distribution and rate of spread of scentless chamomile on the Black and Gray soils in Saskatchewan

Non-Peer ReviewedIn 1987 a questionnaire survey was conducted to determine the distribution of the noxious weed scentless chamomile on the Black and Gray soils of Saskatchewan. As well information was obtained on the year of first sighting, habitats affected, farmers' perception of the problem, the percentage of their land affected, and methods used to control or manage the weed. A total of 29,666 questionnaires were distributed, of which 2120 (7.1 %) usable responses were returned. Of these, 35.6 % indicated that scentless chamomile occurred on land they farmed or on adjacent roadsides. In the group which reported occurrence the most common habitat, reported by 69.5 %, was the roadside. Annual crops were reported as scentless chamomile habitats by 30.0 % and wet areas of fields, which can sometimes be cropped, by 39.0 %. The most common methods reported for control of the weed were tillage, hand-weeding and herbicide use. Of the 214 farmers who indicated herbicide use, 26.2 % used herbicides containing bromoxynil, 16.4 % used herbicides containing dicamba and 15.4 % used glyphosate. Spread of the weed has increased rapidly in the last 20 years. Of the responses to year of first sighting 19.0 % were between 1968 and 1977, and 69.0 % reported first sighting the weed within the last decade

Sigma and omega meson propagation in a dense nuclear medium

The propagation of the scalar ($\sigma$) and vector ($\omega$) mesons in nuclear matter is studied in detail using the Walecka model over a wide range of densities and including the effects of a finite $\sigma$ width through the inclusion of a two-pion loop. We calculate the dispersion relation and spectral functions of the $\sigma$ and (transverse and longitudinal) $\omega$ mesons, including the effect of $\sigma$-$\omega$ mixing in matter. It is shown that the mixing effect is quite important in the propagation of the (longitudinal) $\omega$ and $\sigma$ mesons above normal nuclear matter density. We find that there is a two-peak structure in the spectral function of the $\sigma$ channel, caused by $\sigma$-$\omega$ mixing.Comment: 17 pages including 6 ps files, submitted to Phys. Lett. B. Acknowledgement is revise

The neutron charge form factor in helium-3

In order to measure the charge form factor of the neutron, $G^n_E(Q^2)$, one needs to use a neutron bound in a nuclear target. We calculate the change in the form factor for a neutron bound in $^3He$, with respect to the free case, using several versions of the quark meson coupling model. It is found that the form factor may be suppressed by as much as 12% at $Q^2 = 0.5{GeV}^2$ with respect to that of the free neutron.Comment: 13 pages including 2 ps figure

Geology of the Huntly and Turriff districts : sheet description for the 1:50 000 geological sheets 86W (Huntly) and 86E (Turriff) (Scotland)

This report summarises the results of detailed geological remapping and related studies under-taken by the Geological Survey in the Huntly and Turriff districts of North-east Scotland. It pro-vides an account of the geology to accompany the published 1:50 000 geological maps sheets 86W (Huntly) and 86E (Turriff). The districts occupy a tract of generally rolling country, which ranges from about 50 to 200 m above sea level in its eastern part, to more elevated hilly country, commonly reaching over 300 m and 400 m above OD, in its western and southern parts. The drainage is dominated by the sinuous incised valley of the River Deveron and its main tributar-ies, the rivers Isla and Bogie, except for the southern part of the Turriff district, which is drained by the headwaters of the River Ythan. Agriculture and forestry are the dominant economic ac-tivities, with tourism and whisky distilling also significant. The Huntly and Turriff districts are underlain mainly by Dalradian metasedimentary rocks of Neoproterozoic age that have been strongly deformed and metamorphosed during the Grampian event of the Caledonian Orogeny. The Dalradian rocks have been intruded by igneous intrusions that range from large plutons to small pods and dykes. Granite sheets and pods were emplaced at about 600 million years (Ma), followed later by small ultramafic and mafic bodies. However, the main intrusive igneous event occurred in the Early to Mid Ordovician at 474 to 470 Ma, coeval with the Grampian event. It resulted in the emplacement of mafic and ultramafic plutons, com-monly zoned; the Insch Pluton includes monzonites and syenites in its upper zone. Dioritic and granitic bodies are associated with the plutons. The major structural feature is the north-north-east-trending Portsoy Shear Zone, which traverses the Huntly district. This steeply easterly dipping zone is coincident with a major regional linea-ment, which separates stratigraphically discrete packages of Dalradian rocks with different tec-tonometamorphic histories. The shear zone has also facilitated and in part controlled the emplacement of the Huntly and Knock mafic-ultramafic plutons. The Dalradian metasedimen-tary rocks contain both Buchan and Barrovian metamorphic zonal assemblages. Folding and shearing have caused local repetition of lithological units, but overall the Dalradian sequence be-comes younger eastwards until the broad hinge of the regional Turriff Syncline is reached in the central part of that district. Here, the youngest Dalradian rocks are exposed and metamorphic grade is low (biotite grade). Farther east older Dalradian rocks again crop out and the Buchan metamorphic isograds are re-crossed such that the rocks contain andalusite and sillimanite. Following the Grampian orogenic event the area was uplifted, and during the Early Devonian fluvial and lacustrine Old Red Sandstone rocks were deposited in the northerly trending fault-bounded basins, namely the Turriff and Rhynie basins. In Strath Bogie a basaltic andesite lava unit linked to the Rhynie chert occurs within the Rhynie Basin succession. Subsequently, a Mid-dle Devonian conglomerate-dominated sequence, linked to the Orcadian Lake farther north, was deposited unconformably on the older succession in the Turriff Basin. In the Turriff district deep Tertiary weathering profiles and local fluvial sands and gravels are preserved, testifying to only limited erosion by the later Quaternary glaciations. The Devensian glacial and postglacial history of the districts was dominated by an ice sheet derived from the highland areas farther to the south-west. The related glacial and postglacial superficial deposits form a pervasive if generally thin cover over much of the bedrock. Till derived from the Moray Firth is present in the north-eastern part of the Turriff district. Eastward migration of glacial meltwater gave rise to channels that in places have significantly influenced development of the Holocene fluvial drainage pattern. The Huntly district has been the focus of several periods of exploration since 1970 for platinum group elements, copper and nickel linked mainly to the mafic-ultramafic plutons and their meta-morphic aureoles. The limited drilling and more extensive ground magnetic surveys, in combina-tion with geochemical studies and gravity modelling, have provided detailed information as to the nature, distribution and origin of prospective areas. No economic deposits have been deline-ated to date. However, this BGS report and the geological maps provide a sound foundation for existing and any future commercial and/or conservation-related developments

Weed survey of spring cereals in New Brunswick

En 1986 et 1987, un inventaire des mauvaises herbes a été effectué dans 187 champs de céréales de printemps au Nouveau-Brunswick. Au total, 76 espèces ont été identifiées, 40 d'entre elles étant considérées comme importantes sur le plan agronomique. Environ 50% des espèces étaient vivaces. L'ortie royale (Galeopsis tetrahit), le chiendent (Agropyron repens), la petite oseille (Rumex acetosella), la marguerite blanche (Chrysanthemum leucanthemum), la spargoute des champs (Spergula arvensis) et la stellaire moyenne (Stellaria média) avaient les plus hautes valeurs d'abondance relative. Le chiendent et l'ortie royale avaient les plus fortes densités à 8,0 et 7,1 plantes m-2, respectivement. La densité de mauvaises herbes la plus élevée (103 plantes m-2) a été observée chez l'avoine (Avena sativa) cultivée à la suite de plantes fourragères. La plus faible densité a été détectée chez le blé (Triticum aestivum) suite à une culture de pomme de terre (Solanum tuberosum). La plupart des espèces abondantes étaient tolérantes au MCPA, l'herbicide le plus fréquemment utilisé. Les agriculteurs pourraient lutter plus efficacement contre les mauvaises herbes dans les céréales en choisissant un herbitolérantes au MCPA ou au 2,4-D, et a en pré-plantation ou en post-récolte ses herbes vivaces.During 1986 and 1987, a weed survey of 187 New Brunswick cereal fields was conducted. A total of 76 species were identified of which 40 were considered agronomically important. About 50% of the species were perennial. Hemp-nettle (Galeopsis tetrahit), quack grass (Agropyron repens), sheep sorrel (Rumex acetosella), ox-eye daisy (Chrysanthemum leucanthemum), corn spurry (Spergula arvensis), and chickweed (Stellaria média) had the highest relative abundance values. Quack grass and hemp-nettle had the highest densities at 8.0 and 7.1 plants m-2, respectively. The highest weed density (103 plants m-2) was found in oats (Avena sativa) grown after a forage crop. The lowest density (24 plants m-2) was found in wheat (Triticum aestivum) grown after potatoes (Solarium tuberosum). Most of the abundant species were tolerant to MCPA, the most commonly used herbicide. Farmers could make major improvements in cereal weed control by choosing a herbicide that would control species tolerant to MCPA or 2,4-D, and using preplant or postharvest weed control to minimize the impact of perennial weeds

Volunteer canola (B. napus) in western Canada

Non-Peer ReviewedIn western Canada, survey and small plot research has shown that volunteer canola persists for at least four years in rotation (Derksen at al. 1999; Thomas et al. 1999). It is not clear whether this is due to persistence of the seedbank additions during harvest or the result of replenishment of the seedbank by subsequent volunteers. We are examining the life cycle of volunteer canola beginning with the seedbank additions incurred during harvest and as well as a focus on the seedbank ecology of this species in western Canada. Research in Europe has shown that B. napus can be readily induced into secondary dormancy by a combination of darkness and moisture stress (Pekrun, 1994). Nonetheless, field studies have revealed that only a small proportion of seeds persist via secondary dormancy in Europe (Pekrun et al. 1998). Canadian B. napus genotypes differ in their potential for induction into secondary dormancy using a laboratory assay. While some genotypes consistently exhibit low potential for the induction into secondary dormancy, others consistently exhibit high potential for the induction into secondary dormancy. High temperatures are perhaps the most important contributing factor to the induction of secondary dormancy, while low temperatures rapidly remove secondary dormancy. These observations suggest the seed ecology of a typical summer-annual weed. Furthermore, observations in a field experiment in 2000 revealed that volunteer canola germination was limited to the early portion of the growing season. Spring seedbank evaluations indicated far greater seed viability than was reflected by field emergence. It is was not clear if the seeds that did not emerge lost viability or were induced into secondary dormancy as our lab results would suggest. A more detailed field experiment examining the persistence of B. napus and induction into secondary dormancy was initiated

Winter wheat argronomy survey

Non-Peer Reviewe

Survey of herbicide-resistant wild oat (Avena fatua L.) in two townships in Saskatchewan

Non-Peer ReviewedThe objective of this study was to determine the nature and occurrence of herbicide resistance in wild oat in the Grassland and Parkland regions of Saskatchewan in 1997, based on a systematic survey of fields in two randomly selected townships. The survey found that: 1) over one-half of fields in both townships had populations resistant to Group 1, 2, and/or 8 herbicides; 2) fields in the Parkland township had higher mean levels of Group 1 resistance (% resistant seeds) than fields in the Grassland township, suggesting they were subjected to more Group-1 herbicide applications; and 3) single- (Groups 1, 2, or 8) and multiple-group resistance (1,2; 1,8; 2,8; 1,2,8) were exhibited in populations in fields in both townships. The proportion of fields with populations exhibiting Group 1 (single) resistance was higher, and Group 2 and Groups 1,2 resistance were lower in the Parkland compared to that in the Grassland township. In both townships, farmers with more land (within the township or total farmed) tended to have a greater proportion of that land infested with Group 1- or 2-resistant wild oat compared to those with less land. The nature of resistance in wild oat populations in Saskatchewan is more diverse, differences in distribution and abundance of resistant biotypes between Grassland and Parkland regions are generally less apparent, and occurrence of resistance is more prevalent than previously documented

Identification and distribution of barnyard grass (Echinochloa crus-galli and E. muricata)

Non-Peer ReviewedBarnyard grasses (Echinochloa spp.) have become increasingly prevalent in agricultural fields of the Prairie Provinces during the past 30 years. The taxonomy and identification of the barnyard grasses has been controversial and difficult. At least two annual species occur as weeds in arable fields; the Eurasian Echinochloa crus-galli and the native E. muricata. Although they are relatively easy to distinguish from other Canadian grass weeds by the absence of a ligule, both exhibit considerable morphological variation and are often confused or simply reported as a single species, E. crus-galli. The two species can be most readily distinguished using characteristics of the mature fertile lemmas and paleas. In E. crus-galli the top of the body of the lemma is broadly rounded with an irregular row of hairs. The short acute tip is abruptly different in colour and texture from the body of the lemma. The top of the lemma in E. muricata gradually and smoothly tapers into a pointed tip, without a sharp contrast in texture, colour or pubescence. An examination of about 100 plants collected in 2006-8 and over 240 herbarium specimens suggests that the Eurasian E. crus-galli is less common in the Prairie Provinces than the native E. muricata. The distribution of the species was found to overlap and the two species were occasionally found at the same site. In order to understand any ecological differences that may be important in their effective management, it is critical to be able to recognize the differences between the species in research and control programs. Inconsistencies in reported behaviours and responses, within Canada and other parts of the world, may be at least in part due to the confusion of these two species