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Integrated weed management (IWM) decision strategies in herbicide-resistant canola-production systems were assessed for net returns and relative risk. Data from two field experiments conducted during 1998 to 2000 at two locations in Alberta, Canada, were evaluated. A herbicide-based experiment included combinations of herbicide system (glufosinate-, glyphosate-, and imazethapyr-resistant canola varieties), herbicide rate (50 and 100% of recommended dose), and time of weed removal (two-, four-, and six-leaf stages of canola). A seed-based experiment included canola variety (hybrid and open-pollinated), seeding rate (100, 150, and 200 seeds m−2), and time of weed removal (two-, four-, and six-leaf stages of canola). For the herbicide-based experiment, strategies with glyphosate were profitable at Lacombe, but both imazethapyr and glyphosate strategies were profitable at Lethbridge. Weed control at the four-leaf stage was at least as profitable as the two-leaf stage at both sites. For the seed-based experiment, the hybrid was more profitable than the open-pollinated cultivar, seed rates of 100 and 150 seeds m−2were more profitable than 200 seeds m−2, and weed control at the two- and four-leaf stages was more profitable than at the six-leaf stage. When risk of returns and statistical significance was considered, several strategies were included in the risk-efficient set for risk-averse and risk-neutral attitudes at each location. However, the glyphosate-resistant cultivar, the 50% herbicide rate, and weed control at four-leaf stage were more frequent in the risk-efficient IWM strategy set. The open-pollinated cultivar, 200 seeds m−2rate, and weed control at the six-leaf stage were less frequent in the set. The risk-efficient sets of IWM strategies were consistent across a range of canola prices.

. 2010. Fertilizer response for hybrid and open-pollinated canola and economic optimal nutrient levels. Can. J. Plant Sci. 90: 305Á310. Hybrid (HY) canola (Brassica napus L.) produces a higher seed yield than open-pollinated (OP) canola. While it is expected higher-yielding HY canola may require higher total available nutrients, especially nitrogen (N), the evidence is not conclusive. This study used canola yield data from several site-years and fertility experiments to determine whether HY and OP canola types require different rates of total available N (TAN) and total available phosphorus (TAP). The yield response of the two canola genotypes to TAP was the same, but for TAN the yield response was greater for HY canola. The quadratic yield response results were confirmed using three plateau equations. Optimal TAN for HY canola was higher than for OP canola. Soil test laboratories and producers growing HY canola need to modify N fertility for HY canola, compared with OP canola for which most of the current N fertilizer recommendations were developed. . Le rendement des deux ge´notypes re´agit de la meˆme fac¸on au PTD, mais celui du canola hybride re´agit davantage a`l'ATD. La re´action quadratique du rendement a e´te´confirme´e graˆce a`trois e´quations plateau. La concentration optimale d'ATD est plus e´leve´e pour le canola hybride que pour le canola a`pollinisation libre. Les laboratoires qui analysent le sol et les producteurs de canola hybride doivent adapter les amendements N pour ce type de culture, la plupart des recommandations actuelles en matie`re de fertilisation reposant sur la culture du canola a`pollinisation libre.

G. W. 2006. Economic benefits of integrated weed management systems in field crops in the Dark Brown and Black soil zones of western Canada. Can. J. Plant Sci. 86: 1273-1279. Integrated weed management (IWM) systems that combine seeding date, seeding rate, herbicide rate, and timing of nitrogen (N) fertilizer application were assessed for their economic performance in the Dark Brown and Black soil zones. A barley-field pea IWM system in the Black soil zone at Lacombe, Alberta, and a wheat-canola IWM system in the Dark Brown soil zone at Lethbridge, Alberta, and Scott, Saskatchewan, were used to assess contributions of seeding date (April or May), seeding rate (recommended or 150% of recommended), fertilizer timing (fall or spring), and in-crop herbicide rate (50% or 100% of recommended). The factorial set of treatments was applied in 4 consecutive years at each site. For barley-field pea production, the highest contribution margin (CM) (returns over variable production costs) was earned with 50% of the recommended herbicide rate, spring application of N fertilizer, seeding barley later at the high seeding rate, and seeding field pea early at the recommended seeding rate. This IWM system had a CM benefit of at least $51 ha -1 compared with current common practices. The wheat-canola system results were site specific. At Lethbridge, it was more profitable to use 50% of recommended herbicide rates and to seed both crops early, with an early seeding date being very important for canola. The CM of this IWM system was $48 ha -1 higher than current common practices. At Scott, the wheat-canola system was more profitable with spring fertilizer application, 50% of the recommended herbicide rate, and an early seeding date for canola. The best IWM system had a CM $15 to $75 ha -1 higher, depending on the year, than common practices. Our results confirmed the economic merits of using IWM practices for cereal-oilseed and cereal-pulse cropping systems in these regions of western Canada.Key words: Economic, integrated weed management, contribution margin, canola, wheat, field pea, barley Smith, E. G., Upadhyay, B. M., Blackshaw, R. E., Beckie, H. J., Harker, K. N. and Clayton, G. W. 2006. Avantages économiques des systèmes de lutte intégrée contre les mauvaises herbes pour les grandes cultures dans les zones de sols brun foncé et de sols noirs de l'ouest du Canada. Can. J. Plant Sci. 86: 1273-1279. Les auteurs ont évalué les avantages économiques des systèmes de lutte intégrée contre les mauvaises herbes (LIMH) combinant la date et la densité des semis, le taux d'application des herbicides et le moment de l'application des engrais azotés (N) dans les zones de sols brun foncé et noirs. Ils ont recouru à la LIMH avec un assolement d'orge et de pois dans la zone de sols noirs, à Lacombe (Alberta), et avec un assolement de blé et de canola dans la zone des sols brun foncé, à Lethbridge (Alberta) et à Scott (Saskatchewan) afin d'établir la part de la date des semis (avril ou mai), de la densité des semis (densité recommandée ou 150 ...

Applying a polymer seed coat (PSC) to canola (Brassica napus L. and B. rapa L.) seed could be economically beneficial for dormant fall seeding. Field trials at three locations and across 3 yr were used to evaluate the effect of seeding date, use of a PSC, and canola cultivar on crop yield and net returns. The net returns were used to estimate the economic value of using a PSC for three locations, two seeding dates, and four canola cultivars. Net returns differed across locations, and cultivar differences occurred in one of the three locations. Net returns were higher for late‐fall seeding, compared with early‐fall seeding, with or without the use of a PSC. The value of a PSC was generally positive for early‐fall seeding and negative for late‐fall seeding. However, at a location prone to midwinter mild spells during which seed germination could occur, the PSC generally had no value. Despite the PSC having a positive value for early‐fall dormant seeding, its potential use will be limited because early‐fall seeding with a PSC had lower net returns than late‐fall seeding without a PSC.