Dear Chris,

Brian Wurzell has reported this morning to the British Gall Yahoo Group as follows:

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        Brian Wurzell brian_wurzell@yahoo.co.uk [british_galls] <british_galls@yahoogroups.co.uk>
        Today at 0:44

To:

        british_galls@yahoogroups.co.uk

I can now report that the Silver Maple galls we suspect to be North American Dasineura aceris are widespread throughout north-east London.

My first observation was in Lordship Recreation Ground, Tottenham, in LB Haringey, on August 13th, 2016.   I have now found it in eight further urban locations, ranging from LB's Hackney to Enfield.   I have no doubt it occurs more extensively still.   

Five populations are on Silver Maple, Acer saccharinum.  Three more are on Red Maple, A. rubrum (this is the Canadian nation al tree).   The other is on a horticulturally selected hybrid between the two known as Freeman Maple, Acer x freemanii 'Armstrong.' In each case, these are trees planted for ornament in parks or on pavements.

The opening terminal leaves of lower pendulous shoots (from 1m to 4m high) are nearly always the first to be attacked.   These are followed by single or opposite-pair leaves affected down to the fifth position only.  Galls present themselves as thickened, folded twists of the lamina.  They are reminiscent of the D. plicatrix of brambles but proportionately larger.

Some local trees are already disfigured to a degree that would warrant arboricultural concern.  Indeed if it is not yet regarded as a pest by the RHS, it soon will be.

Do keep a watchful eye on similar trees introduced elsewhere in southern England !

Brian.
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So, can I please ask you to add the Cecidomyiid Dasineura aceris (Shimer, 1868) to teh UKSI and thence to teh Recorder family.

Many thanks.

Steve