DISEASE
 
   NAME
     Beech Bark Disease
     Nectria fungi

Description of the Pest and Disease
Beech Bark Disease is the result of a relationship between a scale and two species of the Nectria fungi.

This yellowish parthenogenetic scale insects (C. Fagisuga ) has a soft covering of wool-like wax and have piercing and sucking mouth parts. The adult female is elliptical up to 1.0mm long and has rudimentary antennae and legs. The female adult dies after depositing the eggs and the emerging nymphs attack the tree turning into the second nymphal stage that is legless. It overwinters at this stage and moults during spring turning into an adult. 

The fungus Nectria galligena forms cankers in hardwood trees producing tiny lemon-shaped fruiting bodies that release the spores during autumn.

		 Damaged Bark
Image by University of Pennsylvania

Period of Activity
The eggs are laid during mid summer on the bark in strings of up to eight and hatch from late summer to autumn. The developed nymphs with legs hatch and migrate to cracks in the bark or are spread by wing to other trees. 

Susceptible Plants
Fagus species are susceptible

Damage Caused
A white waxy secretion of the scale is the first sign of infestation with small white dots appearing on the trunk of the tree or around roughened bark areas. Eventually heavy infestations cover the entire bole of the tree, but the serious damage is caused by the fungus that infects the plant through the scale wounds. 

Dead spots appear and ooze red-brown exudate in some species and this is the first sign of the fungal attack. When the bark of infected trees is pulled away it reveals areas that are orange coloured wood. These areas can be large forming strips or eventually girdle the tree causing ringbark and the death of the tree. Trees that are infected with the fungus have a thin crown of underdeveloped leaves that turn yellow and remain on the branches.
Other fungal diseases and insects invade the weakened tree such as the root rot fungus, Armillariella mellea and the tree is also damaged by wind and commonly known as “beech snap”.

Cultural Control
Dead or damaged parts of the plant should be removed and destroyed. It is difficult to control this problem, but improving vigour by fertilising and watering helps. 

Biological Control 
Natural predators such as lady beetle larva help control scale nymphs. 

Chemical Control
Chemical control in a forest situation is not possible but in domestic gardens small plants may be sprayed using appropriate chemicals. Consultation with your local Department of Agriculture is advised.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.