Large-fruited grey gum

Eucalyptus punctata

Large-fruited grey gum (Clemson, p. 28) flowers in early autumn on the NSW North Coast. If not washed out by rain it can be a beneficial pollen and honey tree.

When it does flower it produces large volumes of light grey pollen and a little honey. The crude protein level in the pollen of 20% to 22% is sufficient, but the iso-leucine can be very variable ranging from 2.9% to 4.0% (Table 11). This possibly accounts for the variation in beekeepers reports about this tree.

In some years, especially in dry autumns, good crops of honey and good bees are obtained, but at times the hives may suffer serious die-offs and apparent nosema problems. These problems arise if rain falls while the tree is in flower. Beehives working grey gum fill the brood nest with pollen, stopping the queen bee laying eggs. The pollen often goes quite hard, and is not used by the bees. In wet years, it is advisable to take the bees from the forest and place them on the best pollen available.

In dry years the pollen of grey gum may be of high enough quality and quantity to trap and store for future use, but if it rains when the tree flowers, it is difficult to keep the pollen dry and stop it becoming mouldy.

There seem to be many subspecies of grey gum, and as many stories about what effect each of these subspecies will have on bees.

It is possible that the great variation in honey production and bee welfare associated with this tree is due to the variation in rainfall as well as the high variation in the iso-leucine content. Dry autumns always seem to produce good crops of honey, while wet autumns are usually disastrous.

Table 11: Large-fruited grey gum Eucalyptus punctata


Amino-acid
Minimum % of Amino-Acid from De Groot (1953)
Grafton March 1987
Kangaroo State Forest

February 1993

Kangaroo State Forest

March 1993

Threonine
3.0
3.7  3.5 3.7 
Valine
4.0
4.0  4.8 4.6 
Methionine
1.5
2.3  1.5 1.0*
Leucine
4.5
6.9  6.0 5.8 
Iso-leucine
4.0
2.9* 4.0 3.9*
Phenylalanine
2.5
4.2  3.6 3.7 
Lysine
3.0
5.2  5.0 5.2 
Histidine
1.5
2.7  1.9 2.5 
Arginine
3.0
6.0  6.8 7.3
Tryptophan
1.0
     
Crude protein   20.37% 19.8% 22.1%
Fat   3.4%    

* Below ideal level for honey bee nutrition


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