This is a bit complex but if there is vigorous growth, the herbicide (whatever was used 11 or more months ago), is apparently not present within the plant in quantities sufficient to cause any plant injury symptoms.  It probably isn't there at all but without a test, it would be impossible to say for sure. The two products  most commonly used to control blackberries  (glyphosate sold as Roundup and other products and 2,4-D+triclopyr sold as Crossbow and other products) have to be absorbed through green leaf and/or stem tissue. The active ingredients don't enter plants through roots so anything that remained in the soil wouldn't enter the plant this year. There is a slight chance that the crown of a plant that was sprayed and survived might have small quantities of the active ingredient in it, but clearly not enough to cause plant damage symptoms.  So with this information, the choice is yours. Call me tomorrow at<personal data hidden> if you need more information. Chip Bubl OSU Extension Service/Columbia County.