9.2.1. Eucalyptus dieback

Eucalyptus dieback is the result of an imbalance in the insect ecology surrounding paddock trees. The natural pest control surrounding the tree is lost and leaf-eating insects abound, gradually defoliating and killing the tree.
It is often difficult to separate the symptoms of eucalypts natural ageing from those of dieback. Trees suffering from dieback usually have thinner, more irregular crowns, many dead branches and hollows.
Eucalypt foliage with enhanced nutritional value (particularly available nitrogen) can promote greater numbers and survival of leaf-eating insects, further stimulating dieback.
More nutritious foliage can result from increased soil fertility beneath trees due to pasture improvements and livestock manure (when stock camp underneath), trees being under stress, and trees having a greater proportion of younger leaves (epicormic shoots).
Understorey trees and shrubs promote natural pest control and play a vital role in tree health. The fact that they have disappeared from many rural landscapes directly affects dieback.
Research has shown that densities of insect-eating birds in areas affected by dieback are about 10% of those in a healthy woodland. The wasp and fly species needed to control scarab larvae also rely on flowering understorey plants such as Blackthorn (Bursaria spinosa) and Tea-tree (Leptospermum spp.) for food.
 

Include photo of tree suffereing from Eucalyptus dieback