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Growing crops that exhibit a high level of competition with weeds increases opportunities to practice integrated weed management and reduce herbicide inputs. The recent development and market dominance of hybrid canola cultivars provides an opportunity to reassess the relative competitive ability of canola cultivars with small-grain cereals. Direct-seeded (no-till) experiments were conducted at five western Canada locations from 2006 to 2008 to compare the competitive ability of canola cultivars vs. small-grain cereals. The relative competitive ability of the species and cultivars was determined by assessing monocot and dicot weed biomass at different times throughout the growing season as well as oat (simulated weed) seed production. Under most conditions, but especially under warm and relatively dry environments, barley cultivars had the greatest relative competitive ability. Rye and triticale were also highly competitive species under most environmental conditions. Canada Prairie Spring Red wheat and Canada Western Red Spring wheat cultivars usually were the least competitive cereal crops, but there were exceptions in some environments. Canola hybrids were more competitive than open-pollinated canola cultivars. More importantly, under cool, low growing degree day conditions, canola hybrids were as competitive as barley, especially with dicot weeds. Under most conditions, hybrid canola growers on the Canadian Prairies are well advised to avoid the additional selection pressure inherent with a second in-crop herbicide application. Combining competitive cultivars of any species with optimal agronomic practices that facilitate crop health will enhance cropping system sustainability and allow growers to extend the life of their valuable herbicide tools.
As a weed, wheat has recently gained greater profile. Determining wheat persistence in cropping systems will facilitate the development of effective volunteer wheat management strategies. In October of 2000, glyphosate-resistant (GR) spring wheat seeds were scattered on plots at eight western Canada sites. From 2001 to 2003, the plots were seeded to a canola–barley–field-pea rotation or a fallow–barley–fallow rotation, with five seeding systems involving seeding dates and soil disturbance levels, and monitored for wheat plant density. Herbicides and tillage (in fallow systems) were used to ensure that no wheat plants produced seed. Seeding systems with greater levels of soil disturbance usually had greater wheat densities. Volunteer wheat densities at 2 (2002) and 3 (2003) yr after seed dispersal were close to zero but still detectable at most locations. At the end of 2003, viable wheat seeds were not detected in the soil seed bank at any location. The majority of wheat seedlings were recruited in the year following seed dispersal (2001) at the in-crop, prespray (PRES) interval. At the PRES interval in 2001, across all locations and treatments, wheat density averaged 2.6 plants m−2. At the preplanting interval (PREP), overall wheat density averaged only 0.2 plants m−2. By restricting density data to include only continuous cropping, low-disturbance direct-seeding (LDS) systems, the latter mean dropped below 0.1 plants m−2. Only at one site were preplanting GR wheat densities sufficient (4.2 plants m−2) to justify a preseeding herbicide treatment in addition to glyphosate in LDS systems. Overall volunteer wheat recruitment at all spring and summer intervals in the continuous cropping rotation in 2001 was 1.7% (3.3 plants m−2). Despite the fact that volunteer wheat has become more common in the central and northern Great Plains, there is little evidence from this study to suggest that its persistence will be a major agronomic problem.
If there is a god who might challenge Cupid’s place as the presiding deity of Love’s Labour’s Lost it has to be Mercury. Obsessed with the use, and abuse of words, the play closes with the gnomic utterance, ‘The words of Mercury are harsh after the songs of Apollo’ (5.2.914–15), which, as they appear in the Folio, may be taken proleptically to refer to the announcement of separation which follows: ‘You that way, we this way’ (line 915). The utterance has attracted a diversity of interpretations, predictably given its enigmatic and sentential character, but there is a more or less general consensus that Mercury and his harsh words represent some form of reality principle which breaks up the Arcadian fantasy world of (the) play, and which is embodied in the figure of Marcade, the messenger who brings the news of the death of the princess’s father. Not only does Marcade correspond to contemporary versions of the god’s name, as several critics have pointed out, but his function corresponds to Mercury’s functions as messenger and psychopomp. There is, however, a more prominent figure that the play invites spectators to associate with Mercury. Linked to Marcade by his dramatic function as well as by his office – he is sometimes grouped with Marcade in the ‘persons of the play’ – ‘honey- tongued’ (5.2.335) Boyet, the only major male figure at the princess’s court, is associated with ‘sweet tong’d’ Mercury both through more general features and, more importantly, through the specific features attributed to him in the two portraits by Berowne, especially the first (5.2.316–35).
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