Blackline

A dark line appears in the cambium where scion meets rootstock. Use compatible scion-rootstock combinations. You are most likely to notice symptoms during periods of active growth, particularly when moisture levels favor pathogen development. Early recognition is your best advantage: the sooner you identify the problem, the more effective your management options will be.

Prevention works better than treatment for blackline. Choose resistant varieties when they exist, site plants where air moves freely, and maintain good sanitation by removing debris and infected material. When chemical intervention is necessary, timing matters more than product: apply protectants before the infection window, not after symptoms appear.