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E. cladocalyx: information for growers

Eucalyptus cladocalyx (Sugar gum) is a species which can tolerate some of New Zealand's driest, toughest sites as long as they are largely frost-free. It produces Class 1 durable timber. E. cladocalyx is not yet part of the main NZDFI breeding programme, but growers are able to benefit from genetic improvement work undertaken in Australia. 

Growing Eucalyptus cladocalyx

Eucalyptus cladocalyx is native to South Australia, where it grows in a small number of distinct locations. Its natural site conditions are extremely dry (250-500 mm of rain per year).

Site requirements

  • Frost tolerance: Minus 3 degrees (E. cladocalyx is generally not a frost-tolerant species).
  • Rainfall min and max:  500 - 1200 mm/year. Prefers dry conditions.
  • Soil type/drainage: Tolerates skeletal and stony soils; will thrive on a range of soil types.
  • Wind tolerance: One of the more wind-tolerant durable eucalypts (all eucalypts grow better on sheltered sites).

Matching eucalypt species to site is essential for good tree survival and growth. Watch our video below, make sure you know your proposed planting site, then ideally talk to an experienced grower or nurseryman before purchasing trees.

Establishment and silviculture

Follow our establishment guidelines for good establishment success.

E. cladocalyx may require some form pruning. Little clearwood pruning should be necessary if growing post and pole wood. For high quality sawlogs, some clearwood pruning at an early age may be necessary.

Read our form-pruning guidelines and watch some videos.

Pest and disease threats

E. cladocalyx has proved to be relatively tolerant of browsing insects such as paropsis in NZDFI's trials to date.

Timing of flowering/potential to support bees

Australian records show E. cladocalyx flowering from January to April.  Data from NZ trials will be reported as soon as available. It is reportedly an excellent source of nectar, and produces good quality honey.

Timber properties and markets

The timber is described by this South African company (Universal Timbers) as relatively stable, with few defects.

 

E. cladocalyx on a very dry site in Marlborough (age 10).

E cladocalyx posts in a Wairarapa vineyard

Honey bee feeding in E.cladocalyx

E. cladocalyx seed capsules.

E cladocalyx planted at 500 metres above sea level.

Performance in New Zealand

E. cladocalyx is not a widely known species in New Zealand. It was selected by NZDFI because of its anticipated tolerance of very dry conditions, given its natural range. Some genetic improvement had already been undertaken by the Australian Low Rainfall Tree Improvement Group, and seed from this breeding programme was available to NZDFI. It is proving to be resilient in NZDFI's driest trial sites.

Performance in Victoria, Australia

E. cladocalyx was included in a series of trials in Victoria, Australia, which have been comprehensively reviewed.

A report: Trials Review, Information and Genetics (TRIG) project is available on the Forestry Australia website.

Durability

Note:  Durability is a complex parameter; NZDFI’s research into heartwood formation will improve our understanding of factors determining durability.

Appearance

  • Heartwood is yellow-brown (blond to tan or honey-coloured)
  • Sapwood is yellow/brown
  • It has a fine interlocked grain
  • If left untreated externally it will turn a silvery grey colour over time.

Applications

Heavy marine and external building applications, railway sleepers, poles and posts, crossarms, outdoor and indoor joinery.