Blog

‘Dynamics of the Horse Chestnut Leaf Miner’, Phil Scott, Forestry Adviser, National Trust

Have you noticed that, by mid-summer, the leaves of the Horse Chestnut often have brown splotchy marks making the tree look like it’s in autumn colours already? Let’s start at the beginning The Horse Chestnut Leaf Miner is totally defined by its English name: It lives on Horse Chestnut trees – mainly the widely planted, white flowering variety and only rarely the red flowering variety It eats the inside layer between the two outer sides of a leaf and so ‘mines’ the leaf We’re not sure where the Horse Chestnut Leaf Miner (Cameraria ohridella) originally came from but it was first found in Macedonia in 1985. It arrived in the UK in 2002 and has rapidly spread throughout most of southern and central UK. It continues expanding northwards and westwards each year. Circle of life A five millimetre long female moth typically lays 20 to 40 single eggs along the […]

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‘No sting in this tale’, Amanda Yorwerth, Observatree volunteer

Amanda and Hannah

Time to act It was quite exciting to get my first proper call to action when it was reported that Oriental Chestnut Gall Wasps (OCGW) had been found in Kent. Obviously it wasn’t good that another tree pest had arrived in the UK, but I set out looking at trees with renewed purpose. There aren’t many sweet chestnut trees around St Albans but people know where they are as they are one of the only wild trees around providing a free harvest. What you see everyday I immediately thought of a short row of sweet chestnut trees on a main road I often cycle past. You know what it’s like, time is always short, so on the way back from a swim I persuaded my daughter, Hannah, to stop off with me for a moment to inspect the trees. She stood there whilst I started at one end of the […]

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‘Chalara Dieback of Ash on my doorstep’, Charles Lane, Plant Pathologist, Fera

Living in rural North Yorkshire, on the border with the East Riding, provides easy access to beautiful areas of the Wolds, Howardian Hills, Moors and coastal regions for country walks. As a Plant Pathologist, it’s a fascinating place to live – being in the front line of the spread of Chalara Dieback of Ash. When going out for regular walks, I now find journey times much slower as I stop to survey for Chalara. Tell tale signs Now is an excellent time to look for symptoms. Without significant undergrowth getting close to young ash, regeneration growth and characteristic stem lesions are easier to spot without too many leaves. From my experience, the most reliable and consistent symptom is the slightly sunken, foxy red-brown lesion centred on a side branch. This frequently causes the death of the leader, resulting in a flush of side shoots at the base as the tenacious […]

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‘How does Observatree fit into tree disease?’, Joan Webber, Principal Pathologist, Forest Research

Observatree project is asking citizens to help in protecting our trees from new pests and diseases, but why is this an issue and why is citizen science part of the answer? First off, the UK is dealing with a sharp increase in threats to our trees from a combination of the increased trade climate change. Since 2001 the UK has seen a near exponential increase in the appearance of new tree pests and diseases. The Government is already very active in this area and it’s approach to controlling new tree pests and diseases is to prevent them from arriving if at all possible, but if they do get here, to eradicate them before they become established. Government scientists at Forest Research are already investigating many of these new threats, collaborating with other scientists in the UK and overseas as well as woodland managers. However, in order for eradication to be […]

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