Identifying color differences in blackberries that direct rednecked cane borer to primocanes

Rednecked cane borer is a pest of blackberries and has the potential to affect 72% of primocanes as a result from girdling of the canes causing a gall formation. This type of injury to the cane can increase the potential of winter injury to the plant and thus affect the yield. Galling of the cane is found only on current year primocanes, leading us to believe that the pest is attracted to the primocanes by either chemical and/or visual cues. The objective of this project was to determine what the color difference is between primocane and floricanes and determine which color the pest is more attracted to. To obtain the color differences, foliage and cane color was measured using a spectrometer and L*a*b values were compared. Paint samples from of primocanes and floricanes were obtained and painted onto metal sheets and wooden dowels. The painted material was coated with Tangelfoot® and placed into blackberry plantings to allow trapping of the pest. Results from the experiment demonstrate that there is a color difference between primocane and floricanes when comparing leaves and canes. Results from the trapping experiment demonstrate that the pest appears to favor one color over the others. Although this pest has demonstrated a color preference, chemical cues emitted by the host plant should be explored to determine which factor elicits the attraction the most.