This autumn horticulture apprentices at Greenwich Park have been busy collecting sweet chestnuts to grow the next generation of the park's trees.
Sadly, some of the sweet chestnut trees in Greenwich Park are affected by a disease called Phytophthora. This tongue-twisting name comes from the Greek for ‘plant destroyer’ as the disease rots plant roots and is often fatal. Diseased trees are unable to take up water, so are particularly at risk during hot summers.
Our arboriculture team have been working with experts from the University of Southampton and Forestry Research to look at ways of controlling the disease. Three trials are being run simultaneously; one involves mulching the trees with a sterilised wood chip, one is using biochar (soil with charcoal) as a mulch, and one involves spraying the tree foliage with a tea-based compound.
Despite these efforts not all the trees will survive and several have already died, so we're going to replace them by growing new trees from the same genetic stock. Phytophthora spores spread in soil and water, but it does not affect plant seeds, so our chestnuts can be used to grow healthy new trees.
It will take at least seven years for the young trees to be ready and tree replacement will happen over the next 10-15 years. Where possible, dead trees will be left standing to provide valuable wildlife habitat – roosts for bats, nest sites for woodpeckers and a food source for insects and fungi.