Weed management systems in spring wheat

Non-Peer ReviewedTrials were conducted at two locations near Saskatoon during 1989 to compare the effectiveness of three weed management systems in spring wheat. A conventional weed management system (pre- and post-emergent herbicides plus tillage) was compared to a conservation weed management system (herbicides and no tillage) and a cultural system (tillage and no herbicide). Each system was used in Katepwa spring wheat seeded at early (May 11) and late (May 29) seeding dates. Herbicides applied prior to crop emergence were pre-selected. Post-emergent herbicides were selected on the basis of the weed populations at each site. The Kernen site was a heavy clay soil which had been summerfallowed the previous year. The Sutherland site was a clay loam soil which was seeded to wheat during 1988. A heavy population of green foxtail (Setaria viridis) dominated the Sutherland site. The Kernen site had a light population of annual broad-leaved weeds. Average grain yields at both sites were in the range of 2000 kg/ha. However, none of the three management systems resulted in increased grain yield. Early seeding resulted in significantly higher weed populations and grain yields at both sites. The average cost of seedbed preparation and weed control operations showed that the conventional, conservation and cultural systems ranked from highest to lowest, respectively. In the absence of a yield response to any system during 1989, the check plots produced the highest net return

Effect of timing of isoxaflutole application on weed control in desi chickpea (Cicer arietinum)

Non-Peer Reviewe

In search of new herbicide chemistries for the prairies

Non-Peer ReviewedThere are a limited of herbicide groups for use in western Canada so there is a need introduce different modes of action to manage herbicide resistant weeds. In addition, many broadleaf crops such as chickpea have limited broadleaf weed control options. Sulfentrazone, a Group 14 PPO inhibitor has been screened in a number of broadleaf crops. Chickpea has exhibited excellent tolerance to sulfentrazone, while the tolerance of other broadleaf crops can be summarized as follows: sunflower and fababean (fair to good); field pea, and narrow-leaved lupin (fair); dry bean (poor) and lentil (very poor). Isoxaflutole is a Group 27 carotenoid biosynthesis inhibitor that may have potential for use in chickpea, tame buckwheat, and narrow-leaved lupin. Sulfentrazone effectively controls many broadleaf weeds but is weak on cruciferous weeds such as wild mustard. Isoxaflutole also controls a number of broadleaf weeds but does not control wild buckwheat. Both sulfentrazone and isoxaflutole are soil-applied herbicides with potential to carry-over and injure rotational crops. Preliminary results from field trials indicate that combined low rates of sulfentrazone and isoxaflutole can result in excellent broad spectrum weed control in chickpea. Carfentrazone-ethyl, a contact non-residual PPO inhibitor has been shown to be an effective pre-seed burndown partner for glyphosate. This would allow for the control of volunteer Roundup-ready canola prior to the seeding of broadleaf crops

Proceedings of the conference on numerical methods in high temperature physics

These proceedings contain full papers presented at the Los Alamos Conference on High Temperature Physics. This conference discussed many aspects of high temperature physics including hydrodynamics, radiation and particle transport and some computational issues important for efficient calculations. The meetings was held between researchers from Los Alamos and the French Commissariat a L'Energy Atomique (CEA)

Microplastics Detected in Groundwater

Low concentrations of microplastics are present in Illinois’ karst groundwater, according to a preliminary study completed in spring 2018. This is the first time that microplastics have been detected in groundwater. The study was conducted in collaboration with scientists at the Illinois State Geological Survey, Illinois State Water Survey, Loyola University Chicago, and ISTC. Full study results published in Panno, S.V., Kelly, W.R., Scott, J., Zheng, W., McNeish, R.E., Holm, N., Hoellein, T.J. and Baranski, E.L. (2019), Microplastic Contamination in Karst Groundwater Systems. Groundwater, 57: 189-196. doi:10.1111/gwat.12862.League of Women Voters of Jo Daviess County; Illinois State Geological Survey; Illinois State Water Survey; Illinois Sustainable Technology Center (Hazardous Waste Research Fund);. Illinois-Indiana Sea Grant (National Oceanic and Atmospheric Administration ; 074483-15907); National Science Foundation (CAREER 1553835).Ope

Analytic solutions and Singularity formation for the Peakon b--Family equations

Using the Abstract Cauchy-Kowalewski Theorem we prove that the $b$-family equation admits, locally in time, a unique analytic solution. Moreover, if the initial data is real analytic and it belongs to $H^s$ with $s > 3/2$, and the momentum density $u_0 - u_{0,{xx}}$ does not change sign, we prove that the solution stays analytic globally in time, for $b\geq 1$. Using pseudospectral numerical methods, we study, also, the singularity formation for the $b$-family equations with the singularity tracking method. This method allows us to follow the process of the singularity formation in the complex plane as the singularity approaches the real axis, estimating the rate of decay of the Fourier spectrum

Population ecology of Psammobates oculifer in a semi-arid environment

We studied the ecology of Psammobates oculifer over 13 months near Kimberley, South Africa, to ascertain if the population’s life history traits conform to chelonian patterns in arid environments. Capture rates were highest in spring and lowest in winter when environmental conditions were respectively most and least favourable for tortoise activity. Body condition did not change from autumn to spring, but reached lower values during the summer drought. Capture effort averaged 5 hours/tortoise, which corresponds closely to that of species with low population densities in arid regions. Population size structure was skewed towards adults, indicative of low recruitment and/or low juvenile survivorship. Females were larger and heavier than males, confirming sexual dimorphism in this species. Body size of cohorts scaled to annuli counts, indicating a close correspondence between body size and age. Telemetered adults deposited one or no growth ring in the year of study; consequently, annuli counts could underestimate adult age. Regression analyses showed that male and female growth rates did not differ, but males matured at a smaller size and younger age than females. The smallest male showing reproductive behaviour had 12 annuli and a shell volume of 157 cm3, while similar measures for females were 14 annuli and 185 cm3. The sex ratio of the population did not differ from 1:1 but the bias towards males in spring, and towards females in autumn, indicates that studies limited to particular seasons can misrepresent life history traits of populations. We concluded that the life history of P. oculifer conforms to chelonian patterns in arid regions.Web of Scienc

Randomly generated polytopes for testing mathematical programming algorithms

Randomly generated polytopes are used frequently to test and compare algorithms for a variety of mathematical programming problems. These polytopes are constructed by generating linear inequality constraints with coefficients drawn independently from a distribution such as the uniform or the normal. It is noted that this class of 'random' polytopes has a special property: the angles between the hyperplanes, though dependent on the specific distribution used, tend to be equal when the dimension of the space increases. Obviously this structure of 'random' polytopes may bias test results