Browsing by Author "Ashford, R."
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Item Canada thistle [Cirsium arvense (L.,) Scop.] control in winter wheat(1987-02-19) McLennan, B.R.; Ashford, R.; Paquette, S.P.Field trials have been conducted since 1983 to evaluate herbicides for crop tolerance and Canada Thistle control in winter wheat. Winter wheat has shown excellent tolerance to a variety of herbicides, both fall and spring applied. Stage of development of shoot apices does not correlate with leaf number in winter wheat as it does in spring wheat. The Zadok scale of development may be preferable to leaf counts in winter wheat in establishing preferable time for treatment with herbicides. Preliminary indications are that the timing of application of systemic herbicides such as 2,4-D is not as critical in winter wheat as it is in spring wheat. Sampling adjacent to and in untreated Canada thistle patches demonstrated a competitive relationship between Canada thistle density and winter wheat yield. Good to excellent top growth control of Canada thistle has been obtained with clopyralid, chlorsulfuron, and metsulfuron applied in late spring. In general, top growth control of Canada thistle has been acceptable with 2,4-D and dicamba until late July. Significant yield increases of winter wheat with effective top growth control from spring-applied herbicides have not been obtained.Item Canada thistle regrowth control one year after herbicide application in winter wheat(1986-02-20) Paquette, S.; Ashford, R.A field study was conducted to evaluate the effectiveness of several herbicides for long-term control of Canada thistle growing in winter wheat. Miscellaneous herbicides were applied at the five leaf stage of winter wheat in the presence of Canada thistle (30 plants per square meter). All herbicides gave effective control of Canada thistle top growth but did not increase yields compared to the weedy check. When Canada thistle control was evaluated one year after herbicide application, three of the nine treatments significantly reduced regrowth: 2,4-D amine at 840 g/ha, clopyralid + MCPA ester at 100 + 400 g/ha, and Clopyralid at 200 g/ha. These treatments reduced Canada thistle numbers by 58, 67, and 83 %, respectively. All herbicide treatments significantly reduced Canada thistle dry matter production one year after application as measured by shoot dry weight per square meter. Clopyralid at 100 g/ha in mixture with either 2,4-D or MCPA ester at 400 g/ha, and 2,4-D amine alone at 840 g/ha reduced dry weight of thistle shoots equally. Clopyralid at 200 g/ha was the most effective treatment tested; Canada thistle shoot dry weight per square meter was reduced by 93 % one year following treatment.Item The effect of vegetable oil carriers and adjuvants on herbicide efficacy(1986-02-20) Hatchard, K.G.; Ashford, R.; Reed, W.B.Item The influence of fall and spring herbicide application on winter wheat(1988-02-19) Derksen, D.A.; Kirkland, K.J.; Ashford, R.A.; Hunter, J.H.; Bowren, K.E.; McLennon, B.R.; Loeppky, H.A.The use of 2,4-D for fall control of winter annuals weeds in winter wheat is recommended in the Canadian prairies but not in other winter wheat production areas. Field research was conducted for two years at several locations using 2,4-0, MCPA, dicamba, dicamba plus 2,4-D, bromoxynil, bromoxynil plus MCPA, chlorsulfuron and clopyralid applied fall and spring. Recommended and double recommended rates were tested to establish the existence of a safety margin. Norstar winter wheat was tolerant to fall applications of all herbicides when applied at recommended rates, however, grain yield was reduced at the double rate with 2,4-D, MCPA, bromoxynil, bromoxynil plus MCPA and clopyralid in some station years. Norstar was tolerant to spring applications of all herbicides except MCPA and clopyralid in several station years. Herbicides tested show promise for use in winter wheat production. Caution is warranted for spring application of MCPA and clopyralid.Item Update on herbicide usage(1979-02-19) Ashford, R.Item Weed problems in longer rotations(1975-02-12) Ashford, R.