Hypsipyla Shoot Borers of Meliaceae in Sri Lanka - Australian ...

locations were generally poorer, with MAI for height
ranging from 0.2 m to 0.8 m over 4 years. Surprisingly,
plantings on mine spoils at Weipa, North
Queensland, produced some trees with height MAI
of 1.5 m, despite poor soils and dry conditions.
The performance of open-grown trees often
deteriorated over time, as trees developed a limby
habit and poor form even as early as two to three
years of age. Form-pruning of young trees and
thinning of mature stems were of little benefit.
Cedrela odorata showed a tendency to regenerate
and coppice vigorously, and in open situations was
susceptible to frost and wind-lodging.
Underplanting and enrichment plantings of
C. odorata have resulted in MAIs of between 0.2 m
and 0.7 m during the first few years. One comparison
between open planting and underplanting beneath 30
year-old Grevillea robusta Cunn. Ex R. Br. produced
height MAI after 11 years of 0.7 m (78% survival)
and 0.4 m (11% survival) respectively (YMN1868 –
details of each trial code are in Tables 5, 6 and 7).
Good growth occurred only under more open conditions,
either beneath an open forest with a canopy
height of 20–30 m (HWD374, HWD375) or following
planting at the same time as the companion
crop (IMB302). Under these conditions, MAIs
exceeding 1.5 m of height were achieved during the
early years. Growth beneath a canopy does reduce
the multiple branching to which the species is prone,
but a heavy canopy cover may restrict growth and
may cause high mortality. Some individuals performed
better when located in more open positions
beneath a canopy, or following thinning of the overhead
cover.
Variability in the performance of trees from different
seed sources have been noted though not
always quantified. In 1986, trials on the coastal lowlands
of North Queensland demonstrated variability
in the performance of different provenances,
including Coyote, Taulabe and Chamelecon in
Honduras, and Matagalpa in Nicaragua. The Coyote
provenance had the best MAI at 4.6 years of 2.7 m,
compared with 2.1 m, 2.4 m, and 2.5 m for other
provenances.
In general, Cedrela odorata received minor
damage from H. robusta and in mixed plantings
were less damaged and grew better than T. ciliata.
Khaya grandifoliola
This species has been planted in one trial on the
Atherton Tableland and has performed well. At age
5.5 years, there was 94% survival and trees had a
MAI of 1.4 m in height and 2 cm in diameter at
breast height (DBH). These growth rates were at
49
least twice those of K. senegalensis, K. ivorensis and
C. tabularis at the same site. Despite these very
promising results, no further plantings were trialed in
the area.
Khaya nyasica
Khaya nyasica has grown well (> 1 m MAI for up to
20 years) in open plantings on frost-free sites in
southern Queensland. This species was generally not
attacked by H. robusta but has a strong tendency to
develop multiple leaders and heavy branching while
still young, requiring heavy and frequent pruning.
Frost damage also increasing the tendency for
branching. Some individual trees had better form,
indicating potential for genetic selection.
Khaya senegalensis
This species grew best under the dry open forest conditions
near Darwin and Weipa (Leggate 1974;
Nicholson 1974; D. Riley, Department of Primary
Industry and Fisheries, Northern Territory, pers.
comm.), responded well to application of fertilisers,
especially phosphorous and potassium, and low
stocking rates, and was resistant to termite damage
(Nicholson 1985). Unfortunately, K. senegalensis
was prone to develop multiple leaders, heavy
branching, and a crooked bole. The reasons for this
poor habit are unknown, but site factors, including
nutrient deficient soils, seasonality of rainfall and
exposure to wind may have contributed. Early formpruning
at approximately 2 m was recommended to
improve form (Nicholson 1985).
Khaya senegalensis did not grow well in enrichment
plantings in north Queensland, and was generally
considered a failure (Keys and Nicholson 1982).
In enrichment plantings, mortality was invariably
greater than 90% within ten years, and growth rates
were poor. In open plantings, mortality was lower
but form and/or growth rate were poor. Damage
from H. robusta was reported at only one site in
north Queensland, when trees were 7 years old and
approximately 2.6 m high.
Swietenia macrophylla
Growth of S. macrophylla has been very variable in
Australia. Most underplantings and enrichment
plantings were not successful due to poor survival,
growth and/or form. In some plantings, trees grew
well, producing MAI in height of 0.9 m and 1.6 m
during the first few years (ATH122, ATH451).
Similarly, many open plantings resulted in high
mortality and poor height growth. Among the more