Tree Diseases
SERIOUS TREE DISEASES
Honey Fungus Armillaria mellea
A fungus affecting conifers and deciduous trees, especially dead tree stumps. It is spread by root contact and rhizomorphs. The symptoms are defoliation, honey coloured toadstools around the base and black bootlace strands (rhizomorphs) in soil and under bark. Also white fungal mass under bark. Honey fungus kills trees in ones and twos in small areas and affects a wide range of trees and shrubs. Death can be sudden or a gradual die-back. Control is difficult in woodlands, so probably need to designate ‘honey fungus hot-spots’ as part of your non-intervention/conservation areas. Remove and burn affected trees if they are on public footpath.
Dutch Elm Disease Ceratocystis Ulmi
Fungal disease affecting the vascular (water) system of the tree. It is carried by bark beetles and has devastated the elm population. Symptoms are die back from the crown, streaks within the wood and fan-shaped beetle galleries on the trunk. There is no remedy, but to reduce further infections, coppice tree and burn all wood (do not store as firewood). Elms do regenerate from suckers but these will usually become infected. The best action is to coppice remaining elm trees every 15 years old, to keep them vigorous.
Fomes Disease Fomes Annosus
A disease mostly affecting commercial conifers. Symptoms are white rot fungi present. This disease spreads after felling, and the most common preventative is to paint urea on fresh stumps. Diseased trees should be felled and burnt.
USEFUL CONTACTS
Welsh woodlands
Small Woodlands Association
Rural Arbor Products Ltd (Insurance)
Forestry Commission
FUNGAL DISEASES WHICH CAN LEAD TO WINDTHROW OR INSTABILITY
Birch Polypore Piptoporous betulinus
Can lead to complete rottenness and windthrow. Enters by wounds.
Beech Bark Disease Nectria coccinea
Can cause internal rot causing trunk to snap. Enters by wounds via scale insect. Mainly SE England.
Giant Polypore – Beech Meripilus giganteus
Causes root decay of beech from wounds. Makes instable and liable to windthrow
Saddleback Fungus Polyporours squamosus
Enters via a wound. Affects broadleaves, causes heart rot and can lead to instability
Chicken of the Woods laetiporous sulphreus
Affects old oaks and many others. Affects heartwood and causes butt-rot so can lead to windthrow
White rot ganoderma applanatum
Affects beech in particular. A bracket fungus, enters via wounds and causes extensive heart rot. Can lead to windthrow.
Phytophthora root rot
Affects sweet chestnut, beech, lime and conifers usually on wet soil.
Sooty bark disease Cryptostroma corticale
Affects sycamore, mainly in south/central England. Prevalent in hot summers.
There are many other diseases which affect trees either benignly or possibly fatally, eg, bacterial diseases such as canker, fireblight, watermark disease, other fungi such as silver leaf, beef steak fungus. Insect damage is not usually a serious problem, although climate change with milder winters is having a notable effect on the populations of some insect species.