Evergreen eucalyptus trees are fast-growing and serve well as wind barriers in excessively windy areas. They are also abundantly planted to prevent soil erosion. However, eucalyptus trees are susceptible to various problems, many of which manifest if the trees are not adequately looked after. It is important to choose only healthy, well-adapted species that are appropriately drought stressed. Eucalyptus trees require no fertilising--that increases the risk of insect damage to certain varieties--and need ample care. Prevention is better than cure when it comes to ensuring the longevity of eucalyptus trees.
Insecticides and Other Chemicals
Eucalyptus trees are damaged by most synthetic insecticides and other chemicals. Insecticides include poisons, fumigants (ethyl formate, methyl bromide and hydrogen cyanide), knock-down (Bioallethrin, Bioresmethrin and pyrethrum) and residuals (Dieldrin, BHC and DDT). The University of California's Agriculture and Natural Resources website advises caution when using insecticides, as the chemicals can damage not only healthy trees, but also beneficial biological control agents and predators.
Eucalyptus trees are susceptible to wind damage. Strong gusts tend to break off weaker branches, which then causes physical damage to healthier parts of the tree. It is imperative that all diseased or damaged branches be timely removed to prevent further damage.
Eucalyptus trees are prone to the detrimental effects of environmental stresses, including excessive cold or hot winds, drought, nutritional imbalances, pollutants, hail damage and insufficient or excess water.
Eucalyptus trees are vulnerable to pest, insect attacks and other biological stresses, including viral and fungal infections and herbivory attacks/damage. The main pests eucalyptus trees are vulnerable to include eucalyptus gall wasps, eucalyptus longhorn borers, lerp psyllids, eucalyptus snout beetle, redgum lerp psyllid, eucalyptus tortoise beetle and many leaf-eating borers.
Fungal diseases that affect eucalyptus trees include eucalyptus rust (caused by puccinia psidii, a fungus spore) and sap rot, which is caused by some varieties of fungus.
Viruses including C. ficifolia, C. gummifera, E. cloeziana also infect healthy and stressed eucalyptus trees.
Younger eucalyptus trees are prone to damage from trampling, browsing and breaking. Rodents can seriously affect mature trees by gnawing on their barks.
Horticultural oil is considered a safer alternative to many chemical-based insecticides. The substance is typically derived from mineral oil and is effective against various disease-causing pests. Heavier doses of horticultural oil damages parts of a eucalyptus tree and must only be used when there is significant damage due to pests.