G.L. Graham1 and W. Brown 2
Abstract: A trial was initiated near Rockville, NB to determine the optimal herbicide application program for quackgrass (Agropyron repens [L.] Beauv.) control in field corn. There were two application timings for the corn herbicides tested. Pre-emergent products consisted of isoxaflutole plus atrazine, s-metolachlor/benoxacor plus atrazine, s-metolachlor/benoxacor plus dicamba/atrazine, dimethenamid plus dicamba/atrazine, pendimethalin plus dicamba/atrazine and s-metolachlor/benoxacor plus atrazine plus mesotrione. The post-emergent products included nicosulfuron plus dicamba/atrazine, nicosulfuron/rimsulfuron plus dicamba/atrazine and foramsulfuron plus dicamba/atrazine. An untreated control was included for crop injury and weed control comparisons. Visual evaluations of crop injury and weed control were recorded. No varietal difference was noted for crop tolerance to the herbicides tested. Quackgrass, lamb's quarters (Chenopodium album L.) and red root pigweed (Amaranthus retroflexus L.) were present in sufficient numbers throughout the plots to warrant rating. As expected, there was no difference noted between the treatments for broadleaf weed control and no herbicide reduced the broadleaf control component within the tank mixes tested. Differences were found with quackgrass control, where post-emergent treatments of nicosulfuron, nicosulfuron/rimsulfuron and foramsulfuron were required for adequate control. No pre-emergent treatment offered commercially acceptable control of this species, although pendimethalin plus dicamba/atrazine and s- metolachlor/ atrazine plus mesotrione offered a low level of suppression. Continued work is required to evaluate the complete spectrum of weeds controlled. Focus should be placed on annual grass species and more difficult to control broadleaf species. Control options and timings in herbicide-tolerant field corn should also be examined.
1NB Department of Agriculture and Aquaculture, Crop Development Branch, P.O. Box 6000, Fredericton, NB, E3B 5H1
2NB Department of Agriculture and Aquaculture, Regional Agri-Business Development, P.O. Box 5305, Sussex, NB, E4E 7H7