It will be several years, however, before the effectiveness of this approach against the redgum lerp psyllid is known. Biological control is often influenced by pesticide use and cultural practices, and effective biocontrol needs to be integrated with these other activities. Cultural Control Minimize tree stress by providing eucalyptus with proper cultural care and protecting trees from injury. Nitrogen levels in foliage may increase when eucalyptus are stressed and increased foliar nitrogen increases reproduction and survival of psyllids. To minimize stress, consider providing trees with supplemental water during periods of prolonged drought, such as during summer and fall in much of California when rain is infrequent or nonexistent.
Drought stress increases damage to trees from both lerp psyllids and eucalyptus longhorned borers.
Psyllid outbreaks may also follow prolonged rainy conditions, possibly because excessively wet soil prevents roots from obtaining adequate oxygen, causing small roots to die and the tree to weaken. When irrigating eucalyptus trees, apply water beneath the outer canopy, not near trunks. Avoid frequent, shallow watering that is often used for lawns. The specific amount and frequency of water needed varies greatly depending on the site, slope, and tree species. Avoid fertilizing eucalyptus.