New Eucalyptus Clones in the market
Clonal hybrids are becoming essential to forestry businesses to enable them to adapt to evolving markets and a changing environment.
A changing climate, emergence of new pests and diseases and volatile markets call for tree plantations that are resilient, adaptable to a wide range of climatic conditions, and can serve multiple timber markets. Clonal hybrids combine favourable characteristics of the two parent species and often result in hybrid vigour.
Hybrids are generally deployed as cuttings (clones) because this allows for the selection of the best individual and then multiplying through a cutting programme. The form and uniformity of clonal hybrids is generally good making them suitable for diverse markets.
NCT manages a programme (Hybrid Clone Consortium-HCC) to screen hybrid material and select individuals for clonal deployment. Member nurseries contribute to funding this programme and have the rights to propagate and sell material developed by HCC. Local nurseries that are part of this programme include CPS Seedlings, Ezigro Seedlings, Sunshine Seedlings and Sutherland Seedlings. Several new clones are now available for purchase from these nurseries.
Warm temperate and subtropical clones:
GU 400 and GU 412:
These two clones are recommended for the Zululand coastal plain. They are tolerant of various pests and diseases such as Leptocybe invasa. GU 400 is an excellent volume producer, whilst GU 412 has better form. These clones should not be planted at mid-altitude, warm temperate regions due to susceptibility to Elsinoe masingae.
GU 411, 483 and 488:
These clones were selected from trials of the old GU 111, 083 and 088. The old clones were mixes of hybrids and the trials were screened to identify good trees that were then fingerprinted and given a new identity.
GU411 is a good volume producer for mid-altitude, high potential sites. It is essentially a cleaned-up clone from the GU 111 mix. It is expected to have similar site requirements and performance to its ‘predecessor’. The clone is tolerant of Elsinoe masingae and has potential as a pole producer.
GU 483 should grow well on mid-altitude, warm temperate sites. It is tolerant of Elsinoe masingae and has good potential as a pole producer.
GU 488 is a cleaned-up clone from the old GU 088 stands. The clone is suited for mid-altitude, warm temperate sites. It can grow well on marginal and/or drier sites. It is also tolerant of Elsinoe masingae.
SU 107:
SU 107 is a E. saligna x E. urophylla hybrid originally bred for sawtimber. It is an excellent volume producer at mid-altitude, high potential sites. The clone is accepted in sawtimber, pole and pulp markets. It has a higher wood density compared to E. grandis and the GU hybrids and will thus give better tonnes over weighbridge.
GL 222:
GL 222 is a E. grandis x E. longirostrata hybrid with excellent form. It grows well on marginal, dry and hot sites. This clone has a similar density to black wattle and will thus give good tonnage over weighbridge. The logs have low splitting, but the high density make chemical penetration into the wood difficult, and pole markets may not accept this hybrid. However, it has potential for peeler log markets. The clone is tolerant of Elsinoe masingae.
Cold-tolerant clones:
GN 389, 311 and 350:
GN 389, GN 311 and 350 are new generation E. grandis x E. nitens hybrid clones that have recently been released to nurseries. GN 311 and 350 have been tested for pole suitability and have acceptable splitting, form and penetration.
GN 350 grows best on sites with deep soils, good rainfall and above 1200m elevation. GN 311 can be planted on more marginal sites above 1100m. These clones should be kept away from snow-prone areas. GN 389 is an excellent volume producer suited for pulpwood. Growth and yield of this clone is significantly better than GN 2107. It should be planted on high potential sites.
GS 211:
This is a novel hybrid between E. grandis and E. smithii with good pulping and paper making characteristics. The clone is tolerant of Phytophthora and can be grown on frost-free sites from 800m to 1300m. It has outperformed seedling and clonal controls in trials planted in this altitude range. Samples have been sent to HKP (NCT wood chip customer) for pulping tests to verify if they will accept wood from this hybrid to be mixed with E. smithii wood chips.
How to plant clones
- Take special care to prepare deep (30cm), friable pits to encourage sinker roots and avoid J rooting. Cuttings lack a strong tap root.
- Make sure that the root plug is not rootbound, a healthy well consolidated plug with healthy white shoots will result in a balanced root system.
- Most clones have plugs with growing medium that drains rapidly, make sure that the plug is saturated before planting. This is especially important for paper-pot plugs.
- Ensure planting teams are well trained and supervised. Blanking (gapping) of newly planted compartments should not be required if the correct planting technique is followed.
Final thoughts:
- For the best results, plant clones on high potential sites. Avoid marginal sites and shallow soils. The exception to this rule is hardy clones such as GL 222 and GU 488.
- Warm temperate/subtropical clones should be kept away from frost and snow prone areas.
- GxNs should not be planted below 1200m due to susceptibility to T. destructans.
- Clones are expensive. Farmers should employ the best site preparation, planting practices, and weed management to get a good return on their investment.
Source: NCT
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