STUDIES ON COW WHEAT (MELAMPYRUM LINEARE DESR.) BIOLOGY AND MANAGEMENT WITH HERBICIDES IN WILD BLUEBERRY (VACCINIUM ANGUSTIFOLIUM AIT.) IN NOVA SCOTIA, CANADA.

Abstract

Weeds are the major limiting factor in lowbush blueberry production with stands consisting of a range of woody and herbaceous perennials. However, recent weed surveys have identified an increased occurrence of annual weeds such as cow wheat (Melampyrum lineare). Various laboratory experiments have been conducted to contribute to the knowledge gaps surrounding cow wheat biology and management in lowbush blueberry fields. Results indicated cold moist stratification duration (CMSD) increased cow wheat seed germination (P < 0.0001), and germination was not affected by the presence of wild blueberry debris. CMSD with or without GA3 increased cow wheat seed germination (P < 0.0001) but there was no effect of agar-gelling agent. There was higher cow wheat seed density on the soil surface relative to subsurface samples (P < 0.0001) in wild blueberry fields. Cow wheat seedlings emerged between April 18 to April 25 with 90% emergence occurring between May 2 to May 26. Cow wheat morphology varied across sites (P < 0.0001) in lowbush blueberry fields. The parasitic connections were visually determined between cow wheat and lowbush blueberry rhizomes at four fields. Cow wheat density was reduced by PRE applications of terbacil (2000 g a.i. ha-1) and indaziflam (75 g a.i. ha-1) at all sites and by PRE applications of hexazinone (1920 g a.i. ha-1), sulfentrazone (139 g a.i. ha-1), tribenuron-methyl (30 g a.i. ha-1), nicosulfuron + rimsulfuron (16.7 + 8.3 g a.i. ha-1), and flazasulfuron (50 g a.i. ha-1) at 3 of 4 sites. POST applications of mesotrione (144 g a.i. ha-1), and foramsulfuron (35 g a.i. ha-1) reduced cow wheat density at 3 of 4 sites but density was not reduced by POST clopyralid applications at any site.