EFFECT OF TIME OF APPLICATION OF HERBICIDES ON YIELD OF THREE WINTER WHEAT CULTIVARS

Abstract

In field experiments at Charlottetown, Prince Edward Island, herbicides were applied in the fall or spring on winter wheat (Triticum aestivum L.) to determine effect on yield. Application of 2,4-D or the mixture 2,4-D/mecoprop/dicamba in the fall gave significantly lower yields than when spring-applied on the cultivar Lennox. The herbicides MCPA, bromoxynil, dicamba, mecoprop, chlorsulfuron, MCPA/dicamba, and MCPA/bromoxynil had no adverse effect on yield of Lennox at either time of application. A further study on the cultivars Lennox, F29-76, and Borden using the herbicides MCPA, bromoxynil, MCPA/dicamba, chlorsulfuron, and dicamba showed no detrimental effects on 1000 kernel weight, or percent winter survival from fall or spring application. Yield losses were noted for spring application of dicamba but not for MCPA/dicamba and all cultivars responded similarly to all herbicide treatments.Key words: Wheat (winter) cultivars, fall versus spring application, 2,4-D, MCPA, dicamba, bromoxynil, chlorsulfuron