Browsing by Author "Devine, M.D."
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Item Evaluation of achieve for control of grassy weeds in wheat(1991-02-21) Yochim, A.D.; Devine, M.D.Field studies were conducted in 1989 and 1990 at Aberdeen, Outlook, and Saskatoon to evaluate the efficacy of Achieve, Hoe-Grass, Assert, and Puma Super for green foxtail (Setaria viridis) and wild oat (Avena sativa) control in wheat. Treatments were applied under both dryland and irrigated conditions and included a range of herbicide rates to determine the dose required for control under each set of environmental conditions. Different weed leaf stages at the time of herbicide application were used to determine the effect of growth stage on herbicide efficacy. Under irrigation, Achieve provided good control of both green foxtail and wild oat at rates as low as 100 g/ha. Achieve activity was greater under irrigated than dryland conditions, suggesting that reduced rates may be used under conditions where moisture is not limiting. The efficacy of Achieve was greatly reduced by a delay in application from the 4-leaf stage to the 6-leaf stage of tame oat. At the 4-leaf stage. rates as low as 25 g/ha were effective; however. at the 6-leaf stage only the full rate (250 g/ha) provided acceptable control. Puma Super provided excellent control of green foxtail under both dryland and irrigated conditions. Overall, Achieve and Puma Super both provided a high degree of control of all weed species in the study. Assert and Hoe-Grass were less effective than the former herbicides.Item Herbicide resistance: dealing with a new weed problem(1993-02-25) Devine, M.D.In recent years, resistance to commonly used herbicides has developed in several weed species in Saskatchewan. The first examples were weeds resistant to herbicides in the sulfonylurea family (e.g., Glean, Ally, and Amber) and included kochia and Russian thistle. Next came green foxtail (wild millet) resistant to dinitroaniline herbicides (e.g., Treflan, Rival, and Edge). In the past two years wild oat and green foxtail samples have been identified that are resistant to many of the newer post-emergence herbicides, including Hoe-Grass, Triumph Plus, Laser, Poast and Achieve. In all cases resistance has developed in individual fields after repeated use of the same herbicide or herbicides with the same mode of action. For some growers, the development of resistant weed biotypes significantly restricts the choice of herbicide available for their weed control program. Growers need to become aware of the modes of action of the different herbicides that are available to them, and to ensure that they use an appropriate rotation of herbicides so that resistance does not increase in their fields. In addition, the use of non-chemical weed control methods should be encouraged, so that growers avoid the repeated use of herbicides.Item Nature and occurrence of herbicide-resistant wild oat and green foxtail across Saskatchewan ecoregions(1998-02-19) Beckie, H.J.; Legere, A.; Thomas, A.G.; Juras, L.T.; Devine, M.D.A survey conducted in 1996 indicated that one in nine fields has Group 1-resistant (R) wild oat and one in twenty fields has Group 1 -R green foxtail in Saskatchewan. However in the Parkland region, one in six fields has R wild oat and one in eleven fields has R green foxtail. One in five Group 1-R wild oat populations exhibits Group-2 resistance; these multiple-R populations greatly restrict chemical control options for producers. Results from this survey should alert producers to be more proactive in preventing, delaying or managing R weeds, by practicing herbicide-group rotation and integrated weed management.Item Weed control for direct-seeded pea and lentil(1997-02-20) Rigetti, S.C.; Holm, F.A.; Devine, M.D.; Schoenau, J.J.; Slinkard, A.E.Field studies were conducted in 1995 and 1996 at two locations to investigate the efficacy of surface applied and shallow incorporated dinitroaniline herbicides in clay loam and sandy loam soils. Three rates of ethalfluralin (0.84, 1.1 and 1.4 kg a.i. ha-‘) and a single rate of triallate/trifluralin (10:4) (1.96 kg a.i. ha-‘), surface applied or shallow incorporated in the fall, were examined for weed control in direct seeded pea and lentil. Crop tolerance and weed control data were gathered to assess the suitability of these herbicides, in combination with a fall herbicide treatment with metribuzin or a spring bum-off treatment with glyphosate, for broad spectrum weed control. Seed yield in lentil and pea was not affected by reduced incorporation of the dinitroaniline herbicides in either year. Green foxtail (Setaria viridis L.) control was excellent and was not affected by weed density. In 1995, wild oat (Avena fatua L.) control was acceptable using both types of application when weed pressures were low to moderate. Wild oat control decreased as weed pressure increased, especially for surface applied treatments. Kochia (Kochia scopuriu L.) was present at the clay loam site in 1996 and control was not acceptable when ethalfluralin was surface applied or shallow incorporated. Wild buckwheat (Polygonum convolvulus L.), was present in 1996 at both sites but control was acceptable only at the clay loam site. A spring bum-off treatment with glyphosate in combination with a post-emergent application of metribuzin in lentil and MCPA-Na salt in pea provided better control of broadleaf weeds than a fall applied metribuzin treatment.