The London Tree Officers Association and the Bartlett Tree Research Laboratory based at Reading University have been undertaking investigations on Planes in London which have been exhibiting signs of stress and disease.
So far, despite detailed study, all results have proved negative for the one we all dread - Ceratocystis platani - or Plane Wilt, which has devastated populations of Planes in France, Italy, Greece and other countries on the European mainland.
These results are provisional and further study of stressed/diseased trees is ongoing.
A number of samples have been submitted to the laboratory but molecular DNA analysis has yet to confirm Ceratocystis.
Laboratory study is, however, expensive and time consuming and has to be combined with the sort of careful observation by an experienced eye, that our members and the scientists at Bartletts possess.
We are looking for symptoms of wilt but we know that our urban Planes are in constant danger from many factors which threaten them - root severance, chemical contamination or a number of other fungal, bacterial, viral, insect and mechanical problems.
Some of these can appear similar and some can pre-dispose our trees to further attack.
The LTOA and Bartletts will continue their partnership with the assistance of our members, who are always on alert to trees under stress.
We have set up a working party to report on best protective measures and co-ordinate our response.
We must always remember that one can prove presence but one cannot prove absence.