Burr knot below the graft union
May 05, 2016 07:40AM
I've got a fair amount of trees (2nd leaf) with burr knot forming below the graft union--typically right where my pea-stone gravel mulch stops. There are little rootlets trying to make a run for it (some of them have actually succeeded). Not really sure what to do about his. If they occur sufficiently below the graft union, my thought was to pull back the pea-stone, put in enough soil to cover the knot, then put the pea-stone back. However, I'm concerned that this will just lead to another burr knot forming higher up. I do think that many of some of the trees are planted with the graft union too high. Some of the unions are a fist above the pea-stone. Any thoughts?

Nat Bouman
Growing cider varieties in Zone 5b
On B.118 at 18X24
Susquehanna County, Pennsylvania
Re: Burr knot below the graft union
May 08, 2016 08:02AM
My experience is that an aboveground burrknot kind of dries up and isn't an issue. This is a Zone 4 observation as regards Bud.118 and MM.111 rootstocks. I typically leave graft union from nursery stock several inches above ground. I also have some trees with graft unions higher up (surplus stock that didn't get grafted for a couple seasons) and don't see burr knots per se. I know it's reported that dogwood borer will seek out burrknots but we don't have that pest here.

Lost Nation Orchard
Zone 4b in New Hampshire
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