In the course of dead-heading a sickly-looking bud on my white rose, I saw a weird brown discoloration at the core of the half-inch diameter cane. Yep, cane borer. I cut down about six inches until I hit about four larva (eeew). Satisfying to cut those things in half.
But my question: How far down do I need to cut? I kept snipping and snipping, looking for a solid white cross-section, but I keep seeing a small dot of brown at the center of the cane, now about 8 inches down (and past a major branch) from where I found the borer larva. The dot is way too small for a larva, but it's the same color brown as the borer damage.
Do I need to keep cutting the cane down to where the cross-section is all white? Or is a brown dot normal for the center of the cross-section of a large healthy cane?? (And yes, I've sealed the cut with glue!)