Small Woodland Owners' Group

Knopper Galls

Trees and Plants!

Postby Twybill » Fri Aug 27, 2010 6:46 pm

This looks like a good year for acorns. The Oaks in our wood are all Sessile with just one Pedunculate (the one with the long stalked acorns). I have noticed that virtually all the acorns on the Pedunculate Oak have turned into monstrosities, called Knopper Galls, but so far I have not found any of these galls on the Sessile Oaks.


The gall wasp which causes this spoilation of the acorns only arrived in this country from Europe in the 1950's and reached the North of England in the 1990's. It would not survive here if the Turkey Oak had not been introduced in 1735, as the gall wasp needs to have part of its life cycle in this tree. There are a good number of 19thC Turkey Oaks near our woodland which clearly will be the 'host' trees.


I am curious why the wasp prefers mainly Pedunculate acorns. Do they have a different chemical makeup or smell? Looking at the near total destruction of the acorns on our single tree, I would imagine this wasp is threatening the long term survival of the English Oak in some areas. Should we be worried? I doubt anyone is proposing felling Turkey Oaks nationally but it self-seeds prolifically and appears to survive harsher conditions and poorer soils.


Twybill
 
Posts: 47
Joined: Fri Dec 04, 2009 7:57 pm

Postby tracy » Mon Aug 30, 2010 12:18 pm

I do know some foresters who are desperate to get rid of the Turkey oak because of this problem....


tracy
 
Posts: 1313
Joined: Wed Feb 06, 2008 6:30 pm


Return to Trees and Plants

Who is online

Users browsing this forum: No registered users and 1 guest