Julie Lajeunesse

The Frequency and Persistence of Volunteer Canola (Brassica napus) in Quebec Cropping Systems

The presence of volunteer canola is becoming a significant agro-ecological concern, given the large-scale use of herbicide-tolerant varieties in some areas. Our goal was to estimate the frequency and persistence of volunteer canola in Québec cropping systems by surveying fields that included a single canola crop since 1995. A survey was conducted in 131 fields in the main canola-growing areas of Québec: in the Saguenay-Lac Saint-Jean region and the Québec City–La Pocatière area. Volunteer canola plants were counted in 0.25-m2 quadrats every 10 m along a W pattern, and every 15 m along the margins of 88 fields. Volunteer canola plants were found in 90% of the fields surveyed and in a wide range of crops, including cereal, corn, and soybean. Average densities of 4.9 and 3.9 plants/m2 were found 1 yr after canola production in fields and field margins, respectively. Volunteer canola densities decreased significantly over time. However, volunteer plants were still present at low densities 4 and 5 yr after production. Dense stands of volunteer canola were found before postemergence herbicide application in no-till fields (9.8 ± 4.1 plants/m2), suggesting that, contrary to what was suggested in the literature, seeds could become dormant in no-till as well as in tilled systems. A small proportion of the volunteer canola plants observed in no-till fields near Québec City and Ottawa included plants that had overwintered, either originating from fall-germinated seedlings, harvested adult plants that had grown new leaves before the onset of winter, or spring regrowth from the base of unharvested adult plants from experimental plots. The presence and persistence of low densities of volunteer canola may not have been a cause of concern until now. However, producers should be made more aware of the potential short-and long-term problems associated with potential gene flow between different herbicide-tolerant canola (HT canola) varieties and also between HT canola and related weed species. Nomenclature: Canola, Brassica napus L.; corn, Zea mays L.; soybean, Glycine max (L.) Merr. Additional index words: Herbicide-tolerant canola, oilseed rape, weed survey. Abbreviations: HT, herbicide-tolerant (canola).

Impact de l’hernie des crucifères [Plasmodiophora brassicae] sur la productivité et la qualité du canola

Clubroot, a disease caused by Plasmodiophora brassicae, first appeared in canola fields in Quebec in 1997. The objective of this project was to assess the impact of a soil infested with P. brassicae on the productivity and grain quality of canola. In 1998 and 1999, 31 cultivars in total (23 of Brassica napus in 1998 or 25 of B. napus in 1999 and 6 of Brassica rapa) were evaluated. In 2000, 25 cultivars and two lines (70584 et 70585) of B. napus and 6 cultivars of B. rapa were tested. These cultivars or lines were sown on a soil where P. brassicae had been prevalent for a few years and on another soil which had never been sown with a cruciferous crop before. The soil infested with P. brassicae reduced canola productivity. Grain yield losses were 80%, 91%, and 85% in 1998, 1999, and 2000, respectively, for the Argentine cultivars (B. napus). In the Polish cultivars (B. rapa), yield losses were 69%, 96%, and 89%, respectively, for the same years. Clubroot also reduced straw yield, oil content of the grain, and the grain mass. As opposed to overall B. napus cultivars, the two lines of B. napus appeared to be resistant to clubroot in 2000. Grain yields of these two lines were not affected by the disease. Since there is no registered canola cultivar tolerant or resistant to clubroot in Quebec, agronomic practices used to prevent or reduce the incidence of the disease should be encouraged.

Benefits of mixing timothy with alfalfa for forage yield, nutritive value, and weed suppression in northern environments

Bélanger, G., Castonguay, Y. and Lajeunesse, J. 2014. Benefits of mixing timothy with alfalfa for forage yield, nutritive value, and weed suppression in northern environments. Can. J. Plant Sci. 94: 51-60. Alfalfa can be grown alone or with a grass, but little information exists on the benefits of mixing alfalfa (Medicago sativa L.) with a grass in northern environments. Our objectives were (1) to determine the benefits in terms of forage yield, nutritive value, and weed suppression of mixing timothy (Phleum pratense L.) with alfalfa and (2) to evaluate the persistence of alfalfa cultivars of varied adaptation to cold and of alfalfa populations selectively improved for superior freezing tolerance in a grass-legume mixture and in monoculture. This study was conducted in a region with 1700 degree-days (5°C basis) with one harvest in the seeding year (2008), three harvests in each of two post-seeding years, and one harvest in the third post-seeding year. Adding timothy to alfalfa increased the seasonal total dry matter (DM) yield by an average of 0.57 Mg DM ha-1 yr-1 in the first 2 post-seeding years and this seasonal effect was due mostly to a DM yield increase at the first harvest. The weed contribution to total DM yield in the three harvests of the first 2 post-seeding years was greater in the alfalfa monoculture (16 to 47%) than in the alfalfa-timothy mixture (12 to 36%). Mixing timothy with alfalfa also increased neutral detergent fibre concentration and digestibility, decreased N concentration, and tended to increase water soluble concentration, but had little effect on forage DM digestibility. Cultivars and populations recurrently selected for superior freezing tolerance did not differ in persistence and had a limited effect on DM yield and nutritive value attributes. The positive effect on DM yield of mixing timothy with alfalfa was not accompanied by a reduction in forage digestibility that is usually observed with increased DM yield.

Impact du précédent cultural et de la fertilisation azotée sur la teneur en désoxynivalénol chez l’orge

Many diseases affect cereals, but fusarium head blight associated with the presence of the fungus Fusarium graminearum is probably one of the most feared diseases in barley (Hordeum vulgare) production in Quebec. In addition to reducing grain yields, the fungus produces the toxin deoxynivalenol (DON), which can affect the health of livestock. An experimental study was conducted over 4 years (2002–2005) at the Research farm of Agriculture and Agri-Food Canada in Normandin to determine the impact of four previous crops (barley, dry pea, soybean, and red clover) and four nitrogen fertilization levels (0, 40, 80, and 120 kg·ha−1) on DON content of barley. The effect of the preceding crop on DON content of barley was significant for 3 years out of 4. Thus, in 2002, 2003, and 2005, the toxin contents were significantly higher when the previous crop was barley compared with dry pea, soybean, or red clover. In 2003, the DON contents were particularly high. For example, when barley was grown the previous year, the average toxin content was 22.5 mg·kg−1. The lowest DON contents were obtained when barley was seeded on a previous dry pea crop with an average content of 10.3 mg·kg−1. The DON contents of barley grown on a previous soybean or red clover crop were 15.2 and 13.4 mg·kg−1, respectively. In 2004, the effect of previous crops had no significant effect on DON content. Similarly, during the 4-year test, nitrogen fertilization had no significant effect on DON content of barley.

Oat mega-environments and test-locations in Quebec

Yan, W., Pageau, D., Frégeau-Reid, J., Lajeunesse, J., Goulet, J., Durand, J. and Marois, D. 2011. Oat mega-environments and test-locations in Quebec. Can. J. Plant Sci. 91: 643-649. The Quebec agricultural regions have traditionally been divided into three zones. Zone 1 includes the small, southern most regions in the Montreal plain, zone 3 includes the large, discontinuous northern regions spreading from the west to the east of the province, and zone 2 includes areas between zone 1 and zone 3. Genotypic main effect (G) plus genotype-by-environment interaction (GGE) biplot analysis of the yield data from the Quebec Oat Registration and Recommendation trials during 2006-2009 revealed that the Quebec oat-growing regions can be divided into two distinct mega-environments: the small zone 1 region and the much larger zone 2 plus zone 3 regions. Due to the large genotype by mega-environment interactions, cultivar evaluation and recommendation must be conducted specifically to each mega-environment. However, a zone 3 test location, La Pocatière, consistently behaved like a zone 1 location in terms of cultivar ranking. Therefore, La Pocatière cannot be used to represent the zone 3 region, and cultivar recommendation for the regions represented by this location should be based on data from this location plus the zone 1 locations. In addition, climatic and soil data were examined in an attempt to explain this observation. The methodology adopted in this work may be of value to similar studies for other crops and in other regions.

Sustainable cereal and forage production in dairy-based cropping systems

Abstract: Our objective was to evaluate the long-term impact of management systems combining rotation types [barley in monoculture (M) vs. barley in rotation with forage (R)], tillage practices [chisel plow (CP) vs. moldboard plow (MP)], and nutrient sources [mineral fertilizer (MIN) vs. liquid dairy manure (LDM)] on forage and barley grain production in the Lac-Saint-Jean region of Quebec, Canada. Barley grain yields were significantly higher in MP (14%) than in CP during the first 10 yr of the experiment only. In R, grain yields were comparable between the two fertilizer sources, but in M, LDM resulted in 17%–20% lower yields compared with MIN. In contrast, forage yields reached 5000 kg ha-1 under LDM, which was 11% more than under MIN. Nutrient uptake was significantly higher under R than under M. In forage production, nutrient uptake was higher under LDM than under MIN. In the long term, perennial forages and barley can be sustainably produced in rotation without productivity loss using LDM and either MP or CP. Residual N effects and non-N benefits from manure and rotation are identified as important factors contributing to cereal and forage productivity.

Effet de la date de semis sur la productivité du lin oléagineux cultivé en climat frais

Pageau, D. and Lajeunesse, J. 2011. Effect of seeding date on oilseed flax grown in a cool climate. Can. J. Plant Sci. 91: 29-35. In Quebec, the growing season is relatively short and most crops are sown early in the spring. However, flax (Linum usitatissimum L.) production is recent in Quebec and the effect of time of seeding on flax productivity has not yet been studied. The objective of this project was to determine the effect of four different sowing dates on the productivity of oilseed flax grown in a cool climate in Quebec. Four planting dates (mid-May to mid-June) were evaluated for 4 yr (2004, 2006, 2007 and 2008) with four cultivars (AC Emerson, AC McDuff, CDC Bethune and Lightning). During 2 yr, delays in seeding reduced grain yields. Moreover, in 2006 and 2007, flax seeded at the last planting date (mid-June) did not reach maturity. Compared with the earliest seeding date, a 2-wk delay in sowing reduced grain yields by 34 to 42% in 2006 and by 25 to 51% in 2007. Late sowing also reduced the oil content and 1000-grain weight of flax. These results indicate that oilseed flax should be sown early (11-18 May) in regions where the climate is cool.

Naked oat response to soil type and herbicides applied at two growing stages

Naked oat (Avena sativa L.) harvested in the province of Quebec, Canada, develops on average 10% covered grains and sometimes more. The objective of this study was to determine the effect of soil type, herbicides and their application stages on the proportion of covered grains in naked oat genotypes. Three genotypes were evaluated over 2 yr at two experimental sites. At each site, trials were seeded on two different soil types and each entry was treated with one of three types of herbicides: bromoxynil/MCPA, dicamba/MCPA and thifensulfuron methyl/tribenuron methyl, and compared with a weed-free check. The herbicides were applied at Zadoks 12-13 and 22-23. Results showed that dicamba/MCPA herbicide, applied at Zadoks 12-13, increased covered grains compared with the weed-free check and more covered grains were produced with the application made at Zadoks 22-23. However, differences in genotype reactions were observed. Few differences were found among the other weed control treatments. The application of di...