My eucalyptus is being attacked by the red gum lerp psyllid. Will the tree get stronger and fight off the psyllid if I fertilize it and water heavily?
No. Practices that stimulate new vegetative growth can weaken eucalyptus trees and hasten their decline when psyllid populations are high. Trees defoliated by the red gum lerp psyllid must use food stored in woody tissues to produce new foliage. Psyllids quickly attack new leaves and cause them to drop during warm weather. Eucalyptus damaged by the red gum lerp psyllid should not be fertilized or heavily irrigated. Trees which have grown under irrigated conditions may benefit from periodic deep watering when soil is dry. Mature trees should be watered near the drip line, but not next to the trunk.