Following on from our last blog post where we shared what we’d been up to this summer, we thought we’d share what the volunteers have all been up to this summer!

In total we had 1247 reports submitted between July and September, which is a lot of trees being looked at!  The Midlands volunteers have been the busiest; we seem to have a bit of a rivalry developing between the West and East Midlands with both regions submitting over 200 reports each this summer.  All regions have submitted reports this summer, which is gives a good range of data across the UK. 

Chalara ash dieback diamond lesion spotted by Karen Holland

130 of these reports were for priority pests or diseases and a further 62 were for non-priority pests and diseases.  Negative reports are also very important for research, as they show scientists what’s happening around the country and help our partners work out where to focus resources.

The most commonly reported priority P&D this summer was chalara ash dieback, which is unsurprising and highlights its unrelenting march across the country. The most common symptoms are discolouring, wilting and death of leaves and shoots, but every now and then someone spots the distinctly-shaped lesion typical of this disease.

The second most commonly reported priority P&D this summer is horse chestnut leaf miner, again reflecting its increasing ubiquity across the UK.

The third most commonly reported priority P&D during the summer was Acute Oak Decline, and all of these reports are now with Forest Research to investigate further.  Acute Oak Decline is a complex disease caused by a few bacteria and it’s most easily spotted by the bleeding lesions on the trunks of infected oaks.

Many volunteers also add notes to their reports of any non-priority P&Ds spotted, and we look at these too for interest!  It’s been a good summer for galls, particularly oak galls. This probably reflects the weather of the last couple of summers and winters

Most the diseases and pests that we keep an eye on do not result in dramatic signs of illness in a tree. It’s one of the reasons the training of the volunteer network and dedicated reports of trees is so important – the network knows what to look for and can spot symptoms that an untrained member of the public might not notice.  Sometimes though, an illness is so obvious that anyone would likely notice and query it!  This Scots pine is clearly very unhappy, with stream of infected material running down its trunk.  The cause of this infection is currently being identified at Forest Research, but bacterial oozes like this are indicative of infection.  They look “frothy” and coloured because there’s a mix of bacteria, yeast and fungi acting on the sugars of the sap oozing from the tree, and can sometimes smell quite pungent!  Oozing like this is reasonably uncommon in the UK and has a number of causes, but does not tend to be contagious so isn’t a serious threat to the long-term health of our trees.

As you have seen we’ve had a busy summer thanks to the hard work of our Observatree volunteers. Autumn is in full swing now but the work doesn’t stop, we still have records coming in and if we see anything else of interest we will be sure to let you know. Be sure to keep an eye out for our upcoming blogs through autumn and winter.