Eucalyptus Species for Lanscape Situations
Eucalyptus trees have a long history in California. They were first introduced from Australia in the late 1800s, and many different species have been planted throughout the state. This has not occurred without problems; for example, eucalyptus have displaced native species in certain habitats and have themselves suffered from several pest epidemics. Three important categories when considering eucalyptus trees for landscape use are lawn tolerance, hardiness, and pest problems. With these considerations in mind, we have prepared the chart below for use in this region. We hope this information will be useful to landscape designers, architects and planners for use in this region.
The chart lists eucalyptus species available in California nurseries in 15 gallon or 24" box size; their height, width, cold tolerance, water needs, lawn tolerance and pests. Three pests in particular have devastated eucalyptus in California: red gum lerp psyllid, eucalyptus long-horned borer and tortoise beetle. Their resistance or susceptibility to these pests is noted in the chart.
Eucalyptus Selection Chart
To find out more information about each tree, click on the botanical name in the chart.
|Botanical Name||Height||Width||Minimum Temp||Water Needs||Lawn Tolerance||Pests|
|E.gunnii||40-75ft||18-45ft||5-10° F||L||Good in lawns. Tolerates poor drainage.||No published information on susceptibility or resistance to longhorned borer or red gum lerp psyllid.|
|E. degulpta||80ft||30-75ft||24-26° F||M?||Probably good in lawns: needs regular water||No published information on susceptibility or resistance to longhorned borer or red gum lerp psyllid.|
|E. maculata||150ft||30-60ft||tolerant of most frosts||L||Possible turf tolerance. Succeeds in subtropical & temperate regions.||Susceptible to spotted gum psyllid (Eucalyptolyma maideni) and lemongum lerp psyllid (Cryptoneossa triangula). Less susceptible to tortoise beetle. No published information on susceptibility or resistance to longhorned borer or red gum lerp psyllid.|
|E. ficifolia||30-40ft||15-60ft||protect from heavy frost||L||Seldom thrives in lawns or hottest climates, though from areas of winter rainfall 30-60 inches annually||Less susceptible to red gum lerp psyllid and tortoise beetle. No published information on susceptibility or resistance to longhorned borer.|
|E. nicholii||40ft||15-36ft||12-15 °F||L||Too much water can cause chlorosis. Needs good drainage. Does not do well in summer rainfall areas, in warm subtropical areas.||Intermediate susceptibility to red gum lerp psyllid. No published information on longhorned borer resistance/susceptibility.|
|E. torquata||15-20ft||15-30ft||17-22 °F||L||Possible turf tolerance. Grows in cool temperate & subtropical regions, best in semiarid warm temp regions.||No published information on susceptibility or resistance to longhorned borer or red gum lerp psyllid.|
|E. forrestiana||10-15ft||frost-resistant||L?||Tolerates limited waterlogging||Proglems with scale & sooty mold. No published information on susceptibility or resistance to longhorned borer or red gum lerp psyllid.|
|E. preissiana||12-15ft||24-26 °F||VL||Not suited for lawns. Dislikes waterlogging. Grows in semiarid & warm to cool temp regions, OK in drier subtropical zones.16-24: rain naturally.||Copper deficiency causes bud drop. No published information on susceptibility or resistance to longhorned borer or red gum lerp psyllid.|
|E. erythrocorys||10-30ft||9-25ft||23 - 26 °F||L||OK in lawns - takes much water if drainage is good (18" naturally)|
|E. lehmannii||20-30ft||15-30ft||frost-resistant||L||OK if well-drained & full sun. OK in part shade. Best in temp semiarid regions. 10: rain naturally, salt-tolerant.||Possible red gum lerp psyllid host - can become infested in California. No published information on longhorned borer restance/susceptibility.|
|E. pulverulenta 'Baby Blue'||18-30ft||6-15ft||15-21 °F||L||Needs well-drained soil||Susceptible to bluegum psyllid, which is under good biocontrol. Less susceptible to red gum lerp psyllid. No published information on susceptibility or resistance to longhorned borer.|
|E. polyanthemos||30-75ft||15-45ft||14-18 °F||L||Needs good drainage||Less susceptible to red gum lerp psyllid and tortoise beetle. No published information on susceptibility or resistance to longhorned borer.|
|E. sideroxylon 'Rosea'||30-90ft||30-60ft||20-25 °F||L||Chlorotic in wet, heavy soil; 15-25" rain naturally||More resistant to longhorned borer. Intermediate to less susceptible to red gum lerp psyllid. Less susceptible to tortoise beetle.|
|E. microtheca||30-60ft||24-54ft||5-10 °F||L||Good (called flooded box) - is thin and erect on clay flats||No published information on susceptibility or resistance to longhorned borer, red gum lerp psyllid tortoise beetle.|
|E. viminalis||30-150ft||24-45ft||12-15 °F||L||OK - good for parks - best in alluvial soils in high rainfall mtn regions w/good drainage||More susceptible to both longhorned borer & tortoise beetle. Intermediate susceptibility to red gum lerp psyllid.|
|E. nutans||4-15ft||Moderately frost-resistant||L?||Full sun-recommended for heavy soil, withstands short periods of waterlogging. Best in semiarid to warm temp regions.||More susceptible to longhorned borer, but less susceptile to red gum lerp psyllid. No information available on susceptibility to tortoise beetle.|
|E. platypus||20ft||Moderately frost-resistant||L?||Not recommended for tropical zones. Best in heavy soil. Tolerates short periods of waterlogging. Sandy soils recommended in cultivation (14" rainfall naturally)||More susceptible to longhorned borer, but less susceptile to red gum lerp psyllid. No information available on susceptibility to tortoise beetle. Has proglems with scale.|
Sources of information used to prepare this chart include the Encyclopedia of Australian Plants Suitable for Cultivation, by W. Rodger Elliot and David L. Jones, and the two volume set Eucalyptus, by Stan Kelly. Cultural information available is limited, and the main sources referenced are the Sunset Western Garden Book, the WOCALS Guide to Estimating Irrigation Water Needs of Landscape Plantings in California (The Landscape Coefficient Method and WUCOLS III), and Bob Perry's Landscape Plants for Western Regions. Pest information is available online at UC Statewide Integrated Pest Management Program.
Red gum lerp psyllid (Glycaspis brimblecombei) is a small sucking insect that lives and feeds on the leaves of certain species of Eucalyptus. Adults and immature insects are found feeding year-round, the adults in the open and the immatures protected under a sugary cone called a "lerp". This feeding causes leaf drop that can defoliate and kill the hardest-hit trees, and sugary honeydew excreted by the insects drips down from the canopy and promotes the growth of sooty mold. The best control of these insects is to provide optimal growing conditions to the host trees. A biological control agent has been released, but it is too early to tell how effective this wasp will be. For more information, see (link to Psyllid Infestation on Stanford Campus in Horticultural Subjects Archive)
Eucalyptus long-horned borers (Phoracantha semipunctata and P. recurva) are beetles whose larvae bore into the wood of blue gum and several other eucalyptus. This boring causes wilting, limb dieback and sometimes death of the affected tree. Several beetle generations occur a year, and stressed or wounded (recently pruned) trees are more at risk. A successful biological control agent is available, and it should be used in conjunction with providing the best growing conditions for affected trees and properly handling Eucalyptus wood.
Eucalyptus tortoise beetle (Trachymela sloaneri) is a leaf-feeding beetle whose host preferences have not been well documented. The adults and larvae chew notches along leaf edges and may eat the terminal growth of new shoots. Because they are nocturnal and often active high up in the canopy, they may be difficult to detect. The recommended management for this pest is to provide the best growing conditions for the affected tree. A biological control agent has been released, but its effectiveness is not yet known.