Help: Oak acorn fungus/blight?

[Joanne Vaughn]

We have an oak tree with numerous acorns. All acorns are blighted like this. Apparently development was arrested. Can anyone help me identify this process so I can decide what to do about this oak?

 

[Brett Chedzoy]

Hard to tell from the picture, but they look like oak galls, not acorns.  Do an internet search for "oak twig and stem galls" and you'll find plenty of information to see if that's in fact what the issue is.  

[Joanne Vaughn]

It looks like an oak gall is the problem here. Sources indicate that removal of affected branches may help save the tree. Luckily the tree is dormant now so removing and burning the infected material is the first and second step. spraying with something is second step --- unfortunately this tree is located in an apiary.  The tree is not large, only about 20-25' tall .  Might a severe pruning save the tree without spraying. It is a relatively isolated oak with only a maple nearby. 

It is interesting that they are made of a tannin compound that can be used to tan leather or as a mordant for a wool dye. 

Brett Chedzoy said:

Hard to tell from the picture, but they look like oak galls, not acorns.  Do an internet search for "oak twig and stem galls" and you'll find plenty of information to see if that's in fact what the issue is.  

[Joanne Vaughn]

1 yr follow up: We could not remove all of these from the infested tree. This year another tree shows these as well.  They most closely match Cola-nut galls which are hosted by oaks. 

Wiki says:

The imago of the agamic phase emerges in early summer following the gall's inception. The bisexual generation gall is very similar to that of A. kollari, effecting the live bud of Quercus species^[2] and has only been seen under culture conditions (1975).^[3] Removing and destroying cola-nut galls before they dry and the wasps emerge may help to reduce an infestation. While fairly large, and sometimes present in quite large numbers on scrub specimens, they cause no measurable harm.