Agriculture, Aquaculture and Fisheries - Evaluation of Herbicides for the Control of Borage, Calendula and Cuphea in New Brunswick Rotational Crops

Abstract: Borage (Borago officinalis), calendula (Calendula officinalis) and cuphea (Cuphea viscosissima x C. lanceolata) are potential new crops for New Brunswick producers. Harvesting methods for these crops are not perfected and a large number of seeds could potentially be lost before and during the harvesting process. These volunteers could act as weeds in future crop rotations. Herbicide control options for borage, calendula and cuphea within the following crop rotations (potato, cereals, field corn and forages) need to be evaluated. A trial was initiated near New Denmark, New Brunswick to evaluate rotational crop herbicides for control of borage, calendula and cuphea. Within potato production, metribuzin would be the best choice for control of all volunteers, and could be followed by rimsulfuron if late escapes were detected. Herbicide choice in conventional corn production would depend on volunteer species, but a tank–mix of dicamba/atrazine should control all the species. Within cereal production, thifensulfuron/tribenuron would give the highest control, while the Group 4 products tested would suppress populations. Glyphosate would be effective as a pre–seed burnoff, in–crop for Round–up Ready varieties or as an emergency treatment under very high volunteer populations. Volunteer borage, calendula and cuphea have herbicide control options within typical New Brunswick cropping systems.