There can be little doubt that this is the gravest threat facing the whole of UK horticulture from growers to garden centres, from botanical gardens to landscapers.
We have Gathered together some information on Xylella here.
Advice for the HTA, this is a link to the Xylella page on the HTA website.
Advice from the Plant Health Inspectorate clicking on this link will open this document.
The HTA have also produced a Youtube Video on the subject.
We would recommend that your plant buying teams and all planetaria staff make themselves aware of Xylella.