Weed resistance monitoring has been routinely conducted in the Northern Great Plains of Canada (Prairies) since the mid-1990s. Most recently, random surveys were conducted in Alberta in 2001, Manitoba in 2002, and Saskatchewan in 2003 totaling nearly 800 fields. In addition, nearly 1,300 weed seed samples were submitted by growers across the Prairies between 1996 and 2006 for resistance testing. Collected or submitted samples were screened for group 1 [acetyl-CoA carboxylase (ACCase) inhibitor] and/or group 2 [acetolactate synthase (ALS) inhibitor] resistance. Twenty percent of 565 sampled fields had an herbicide-resistant (HR) wild oat biotype. Most populations exhibited broad cross-resistance across various classes of group 1 or group 2 herbicides. In Manitoba, 22% of 59 fields had group 1–HR green foxtail. Group 2–HR biotypes of kochia were documented in Saskatchewan, common chickweed and spiny sowthistle in Alberta, and green foxtail and redroot pigweed in Manitoba. Across the Prairies, HR weeds are estimated to occur in fields covering an area of nearly 5 million ha. Of 1,067 wild oat seed samples submitted by growers and industry for testing between 1996 and 2006, 725 were group 1 HR, 34 group 2 HR, and 55 groups 1 and 2 HR. Of 80 submitted green foxtail samples, 26 were confirmed group 1 HR; most populations originated from southern Manitoba where the weed is most abundant. Similar to the field surveys, various group 2–HR biotypes were confirmed among submitted samples: kochia, wild mustard, field pennycress,Galiumspp., common chickweed, and common hempnettle. Information from grower questionnaires indicates patterns of herbicide usage are related to location, changing with cropping system. Two herbicide modes of action most prone to select resistance, groups 1 and 2, continue to be widely and repeatedly used. There is little evidence that growers are aware of the level of resistance within their fields, but a majority have adopted herbicide rotations to proactively or reactively manage HR weeds.

. 2009. Impacts of agronomic practices on the leaf spotting complex of common wheat in eastern Saskatchewan. Can. J. Plant Sci. 89: 717Á730. A survey of commercial common wheat crops was conducted in eastern Saskatchewan (2000Saskatchewan ( to 2002 to determine the effects of agronomic practices on the leaf spot (LS) disease complex and causal pathogens, and to determine the impact of LS on crop productivity. Leaf spots had a negative impact on grain yield, but did not affect market grade consistently. There was little effect of agronomic practices on LS severity, but cropping sequence and tillage system affected the mean percentage fungal isolation (MPI), whereas only tillage affected the percentage fungal occurrence. A previous noncereal crop, which had in most cases been preceded by a cereal, resulted in a higher MPI of Pyrenophora tritici-repentis (Ptr), the most common pathogen, and a lower MPI of the septoria leaf blotch fungi Mycosphaerella graminicola (Mg) and Phaeosphaeria nodorum (Pn). Levels of Ptr tended to be lower after 2 yr of noncereals, grown mostly under zero tillage. Overall, the MPI of Ptr increased with a reduction in tillage, being most common under zero tillage, whereas the septoria leaf blotch fungi were least common under zero tillage, and Cochliobolus sativus (Cs) was most prevalent under conventional tillage. The highest MPI of Cs occurred after summerfallow under conventional tillage. Tillage effects also varied with cropping sequence, being most pronounced after another cereal. Pyrenophora tritici-repentis was also associated with recommended or high seeding rates and with high N fertilizer input, although these factors might have been confounded by tillage system and cropping sequence, respectively. Overall, our findings indicate that in eastern Saskatchewan Ptr infection of common wheat prevailed in high-yielding and high N systems that included previously grown noncereals grown under zero tillage and seeded at recommended to high rates, whereas Pn, Mg and Cs occurred the most in lower-yielding and lower N systems preceded by another cereal crop or summerfallow under conventional tillage. However, LS severity was not significantly or consistently affected by any agronomic practice, which was attributed to the presence of all the most common LS pathogens in the region and years this study was conducted.Key words: Wheat, oilseed, pulse, summerfallow, leaf spots, tan spot Fernandez, M. R., Pearse, P. G., Holzgang, G., Basnyat, P. et Zentner, R. P. 2009. Impact des pratiques culturales sur la septoriose du ble´dans l'est de la Saskatchewan. Can. J. Plant Sci. 89: 717Á730. Les auteurs ont entrepris une enqueˆte sur le ble´cultive´dans l'est de la Saskatchewan (2000 a`2002) en vue de pre´ciser l'incidence des pratiques agricoles sur la septoriose et sur les agents pathoge`nes qui en sont la cause, ainsi que pour de´terminer l'impact de cette maladie sur le rendement des cultures. La septoriose diminue le rendement du ble´, mais n'a pas d'impact cohe´rent sur sa qualiteć ommerciale. Les ...

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Discoloration of subcrown internodes (SIs) and crowns/lower culms (CLCs) of 87 oat crops across Saskatchewan in 1998-1999 and of SIs in 31 oat crops in eastern Saskatchewan (Black Soil Zone) in 2000-2001 was evaluated. Fungi in discolored tissue were isolated, identified and quantified, and the percentage of fields from which each fungus was isolated at least once (occurrence) and their relative percentage isolation levels were determined. In the 1998-1999 survey, discoloration severity varied more between years than among soil zones. Fusarium was the most common genus present, and F. culmorum the most common species. This was followed by F. equiseti, Microdochium bolleyi, Cochliobolus sativus, and F. avenaceum. Levels of C. sativus were lower in oat than those reported for wheat and barley in parallel province-wide surveys. Percentage isolation of F. culmorum was higher in the Brown than in the Black/Dark Gray Soil Zone, whereas the percentage occurrence of F. avenaceum was highest in the Black/Dark Gray Soil Zone. In 2000-2001, in eastern Saskatchewan, M. bolleyi, F. avenaceum, C. sativus, F. equiseti, Alternaria spp., and Pyrenophora avenae were the most common fungi isolated from discolored oat SIs. Similar to reports from wheat and barley, F. graminearum was isolated from SIs in eastern Saskatchewan at low levels. For the most part, neither previous crop nor tillage system affected fungal levels in SIs. P. avenae levels increased when the previous crop was another oat rather than wheat or barley. We conclude that oat could maintain or increase inoculum levels of Fusarium pathogens that cause damage to cereal crops in Saskatchewan. This is supported by results from a crop residue study in eastern Saskatchewan that showed that F. avenaceum, F. culmorum and F. graminearum occurred at similar or higher levels in oat fields than in fields of wheat or barley. Key words: Oat, root rot, crown rot, crop rotation, tillage system, Fusarium head blight, Fusarium spp., Fusarium avenaceum, Fusarium culmorum, Fusarium graminearum, Cochliobolus sativus, Pyrenophora avenae