Friday, 5 July 2013

Ash Tree Problems

Ash leaflet distorted by a Prociphilus aphid.
Boddington Road, Byfield 4 July, 2013
With much talk of Chalara (the fungus Chalara fraxinea) I have been keeping an eye on local ash trees for signs of disease. Ash (Fraxinus excelsior) can be afflicted with various problems but few appear to have serious effects. Along the Boddington Road the leaflets of one tree were badly distorted by the activities of an aphid belonging to the genus Prociphilus. It could be Prociphilus bumeliae or P. fraxini but, although I suspect the former I cannot yet be sure.

Two views of the gall caused by Dasineura fraxini.
Boddington Road, Byfield. 4.July, 2013
Only a few metres away an ash tree was exhibiting a different affliction. The pouch-like galls on the leaflets are the work of a fly, Dasineura fraxini. As with the Prociphilus aphids the tree seems to suffer no ill-effects.

Another fly with a confusingly similar name was also at work, causing yellowing of the leaf and forming tiny pimple-like galls. This was caused by Dasineura fraxinea. Being inconspicuous, these galls are easily overlooked.
Ash leaf attacked by the fly, Dasineura fraxinea
Boddington Road, Byfield  4 July, 2013

But so far, I am pleased to report, I have not seen Chalara locally.

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