Seed yields of canola and volunteer barley as influenced by their relative times of emergence

O’Donovan, John T.

doi:10.4141/cjps92-031

Cited by 19 publications

(13 citation statements)

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“…Postharvest application alone was agronomically equivalent to the best POST application in 2002, but not 2003, for which seed yield was lower, possibly because of interference from weeds emerging in the spring of that year. The finding of abundant canola production after PREPLANT glyphosate application is in agreement with a number of studies reporting that early weed removal is important to maximize canola yield (Clayton et al 2002;de St. Remy and O'Sullivan 1986;Martin et al 2001;O'Donovan 1992). in conventional canola was reflected in the greenhouse dose-response assay.…”

Section: Resultssupporting

confidence: 89%

Effect of Herbicides on Field Violet (Viola arvensis) in Four Direct-Seeded Canola Management Systems

et al. 2005

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Field violet is a winter or summer annual plant that is a serious weed of canola crops in Europe. It is a weed of increasing concern within reduced tillage fields in central Alberta, where its response to registered herbicides has not been evaluated. Two commercial fields within the Aspen Parkland ecoregion of Alberta were used to evaluate the efficacy of postemergence (POST) herbicides against field violet in conventional, imidazolinone-resistant (IMI-resistant) and glufosinate-resistant canola cultivars, as well as to evaluate the plant's response to various timings and rates of glyphosate in glyphosate-resistant canola. Control of field violet was lower in field experiments conducted in 2002 compared with 2003, probably because of abnormally low rainfall in 2002. The POST herbicides evaluated provided inadequate control of field violet in conventional canola. Glufosinate control at 500 g ai/ha was unacceptable unless the crop canopy closed shortly after application. In IMI-resistant canola, thifensulfuron did not significantly reduce plant density and biomass under the extremely dry conditions experienced in 2002, but in 2003, it conferred respective reductions of 79 and 86% relative to nontreated controls. Imazamox plus imazethapyr did not affect plant growth. Field violet was controlled by pre- and postcrop emergence glyphosate at 445 g ae/ha. Postharvest application of glyphosate provided good control throughout the following growing season when spring emergence was minimal. Herbicide activity was also evaluated on two- to four-leaf seedlings in a greenhouse experiment. Dose– response curves reflected the activity observed in field experiments. Strategies for effective field violet control with herbicides are dependent on cultivar selection and the management system, but are improved by timing application to young, actively growing plants.

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Section: Resultssupporting

confidence: 89%

Effect of Herbicides on Field Violet (Viola arvensis) in Four Direct-Seeded Canola Management Systems

et al. 2005

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“…In all instances, there was a linear increase in canola yield as glyphosate was applied at earlier leaf stages of the crop (Table 4). This supports the conclusion that earlyemerging weeds cause the greatest reductions in crop yield (O'Donovan 1992;O'Donovan et al 1985;Peters 1984). Martin et al (2001) showed that weeds can remain in canola up to the four-leaf stage without a yield loss greater than 5%, because of the plasticity of canola in recovering yield potential once the weeds were removed.…”

Section: Resultssupporting

confidence: 72%

Glyphosate Timing and Tillage System Effects on Glyphosate-Resistant Canola (Brassica napus)¹

Clayton¹,

Harker²,

O’Donovan³

et al. 2002

Weed Technology

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Glyphosate-resistant canola has been widely adopted in western Canada. This has prompted producer interest in the timing of glyphosate application, particularly under zero tillage, where glyphosate is often applied preseeding. Field experiments were conducted at Lacombe, Edmonton, and Beaverlodge in Alberta in 1997, 1998, and 1999 to determine the importance of preseeding glyphosate and the most effective growth stage to apply glyphosate to canola to optimize yield and weed management. Treatments consisted of zero-tillage systems, with and without preseeding glyphosate, and a conventional-tillage system involving preseeding tillage operations. Glyphosate was applied at the one- to two-, three- to four-, or five- to six-leaf stages of canola in each tillage system. Canola yield and weed dry weight were largely unaffected by the tillage system. In most instances, the highest canola yields occurred when glyphosate was applied early to the crop. The opposite occurred at Lacombe and Edmonton in 1999, however, where canola yield increased as glyphosate was applied at later crop growth stages. This yield benefit likely resulted from the control of late-emerging weeds that exerted competitive pressure on canola. Early glyphosate timing in glyphosate-resistant canola may eliminate the need for preseeding glyphosate in zero-tillage systems, and optimize yield and weed control.

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“…However, the impact of the weed on crop yield loss varied among years, and no attempt was made to incorporate a relative time of emergence parameter into the equations. This factor can be at least as important as weed density when assessing crop yield loss due to wild oats (Cousens et al 1987) and volunteer barley (O'Donovan 1992).…”

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confidence: 99%

Relationship between relative time of emergence of Tartary buckwheat (Fagopyrum tataricum) and yield loss of barley

O’Donovan¹,

McClay²

2002

Can. J. Plant Sci.

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Seed yields of canola and volunteer barley as influenced by their relative times of emergence

Cited by 19 publications

References 1 publication

Effect of Herbicides on Field Violet (Viola arvensis) in Four Direct-Seeded Canola Management Systems

Effect of Herbicides on Field Violet (Viola arvensis) in Four Direct-Seeded Canola Management Systems

Glyphosate Timing and Tillage System Effects on Glyphosate-Resistant Canola (Brassica napus)¹

Relationship between relative time of emergence of Tartary buckwheat (Fagopyrum tataricum) and yield loss of barley

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Seed yields of canola and volunteer barley as influenced by their relative times of emergence

Cited by 19 publications

References 1 publication

Effect of Herbicides on Field Violet (Viola arvensis) in Four Direct-Seeded Canola Management Systems

Effect of Herbicides on Field Violet (Viola arvensis) in Four Direct-Seeded Canola Management Systems

Glyphosate Timing and Tillage System Effects on Glyphosate-Resistant Canola (Brassica napus)1

Relationship between relative time of emergence of Tartary buckwheat (Fagopyrum tataricum) and yield loss of barley

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Glyphosate Timing and Tillage System Effects on Glyphosate-Resistant Canola (Brassica napus)¹