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Horse chestnut trees combat the Leaf Miner moth with waste materials

Last Updated:  11/12/2017

With more than 200 horse chestnuts on Stockley Park, Uxbridge, the Leaf Miner moth poses a very real threat to the habit of the 150-acre site.

Pieter Borchardt, Estates Director, is determined to fight back to maintain the eco-system, not only for the 7,000 individuals working there, but also for the increasing variety of wildlife on the park. He has enlisted the help of Dr Glynn Percival to trial an approach that not only avoids the use of indiscriminate and harmful pesticides, but also reduces landfill.

Pieter said:

“The parkland setting is so very important to the wellbeing of everybody working on the park, it is an integral part of how we add value to our professional lives. In addition, we owe it to the heritage of the park to look after the flora and fauna for future generations.”

The horse chestnut leaf miner (Cameraria ohridella) was first reported in the UK in 2002, in the London Borough of Wimbledon, and has since spread to most of England. The effects of this moth on the horse chestnut tree have been devastating. Severely damaged leaves shrivel and turn brown by late summer and fall early, well before normal leaf fall in the autumn. (Photograph 1).

Image 1. Symptoms of horse chestnut leaf miner

Image 1. Symptoms of horse chestnut leaf miner

Photograph 2 –Treated and untreated

Photograph 2 –Treated and untreated

Untreated trees will eventually defoliate and decline, leaving them vulnerable to other diseases. Once established, the moth maintains exceptionally high rates of infestation, unless frequent insecticide sprays are used.

For these reasons, a unique and environmentally benign management technique was evaluated on five horse chestnut trees located at Stockley Park, Uxbridge, Middlesex by Dr Glynn Percival, Head of Research for Bartlett Tree Research Laboratory at Reading University.

The results of this technique have shown a noticeable improvement in the health of the trees, compared with neighbouring untreated trees.

The soil around each tree was treated with a unique combination of organic products to include chitin (a waste sea food product), phosphites (a natural fertiliser), biochar (a form of activated charcoal) and pure mulches i.e. a mulch made from a single tree species such as willow or eucalyptus.

These soil amendments have been shown to “switch on” a plant's own defence mechanisms and make them naturally more resilient to attack. The results have been impressive as Photograph 2 demonstrates with marked difference in leaf mining severity between treated and non-treated trees. Importantly, all of the products used in the study were derived from waste or natural compounds which could have ended up as landfill.

Image 3: Dr Glynn Percival, Head of Research for Bartlett Tree Research Laboratory at Reading University.

Image 3: Dr Glynn Percival, Head of Research for Bartlett Tree Research Laboratory at Reading University

Dr Percival said:

“By boosting the tree’s own immune system, using natural waste materials, the tree becomes more resilient to not only the Leaf Miner moth, but to other pests and diseases. My aim with this research is to make people think differently about tree health and look and more sustainable ways to deal with tree pests and diseases.”

For more information and research, contact Jayne Tamlyn on or 07985 364415.

Image 4: Stockley Park

Image 4: Stockley Park

Image 5: Stockley Park

Image 5: Stockley Parky

Image 6: Stockley Park

Image 6: Stockley Park