BLUE GUM BLIGHT.

Manawatu Times, Volume XLVI, Issue 2644, 12 May 1923, Page 7

BLUE GUM BLIGHT.

Mr K. W. Dairymple writes very Interestingly concerning the blight in the blue gum plantations which is causing so much concern among farmers in this district. He says;—

Gum trees of all kinds arc being attacked by a scale blight, the first easily observed sign being the oily appearance of the leaves, due to a secretion called “Honcydew” exuded by the insect. This honeydew is attacked by a fungus which gives the trees the black appearance so commonly seen now, and wrongly called “fire blight.” It would be well for anyone with any kind of gum tree, although it is showing no sign of blight, to look over the trees from time to time, and there- will be found sooner or later a collection of greyish egg-liko attachments on the small branches and twigs, or white scale insects on the rib in the centre of the leaves, which if crushed with the fingers makes a deep red stain. This is the beginning of trouble for the tree. The cure is to get as many as possible of a ladybird that lives on the scale and place them on the tree. These can be had by anyone who will take the trouble to collect them, and Mr Alec. Howard of “Westoe,” Groatford, has no objection to persons wishing to get a supply, getting them from his plantation along the road just above the Greatford railway staprovided this concession is not abused. The ladybirds will bo found in great numbers, during the cold weather under the bark of the trees. The ladybird itself, seen through a magnifying glass, is about 1-8 in. long about half as broad, and is shiny black with greyish hairs, has six legs, and emits a reddish yellow fluid when disturbed. The' ladybird grub, the half-grown insect, will be found in colonies alongside, they are rather like an ordinary wool louse or slater, but dark brown in colour with a yellowish tinge, bigger than the ladybird, and have three large and about twelve hairlike logs on each side. Remove the bark carefully with the ladybirds and grubs on it and place in a cardboard box, which is a good way to carry them, and then place the piece of bark in a crack or under a piece ftf loose bark on the tree which has the scale on it. The ladybirds will not live on a tree that lias no scale on it.

On a badly infected tree masses of white eggs will bo found. These at times can be seen from quite a distance; on others the loose bark will be found to be covered with them. Tills is a good home for the ladybird and the grubs. The eggs belong to the scale and form good winter rations for the ladybird and her young. During the winter the ladybirds are more or less dormant but become active at once in warm weather. It can be understood that a cure cannot be expected at once as the scale has had a great start, but the lady bird Is very prolific and next year should see them got the upper hand. The scale is common in Australia and Tasmania, but is kept down there by its natural enemies. We have lo thank our want of system of inspection of imported timber for the damage it is doing here. It quite likely came here in the bark which is left on some of the. poles imported from Australia. It is not known yet how the scale travels from plantation to plantation, but they can be spread by means of the bark. All varieties of gum are attacked by the scale, but particularly the com-

mon bluegum and especially when it has been attacked by the gall chalcid and probably also when the roots are bruised by stock or other traffic. The earth over 1 the roots of a tree should not be trampled down.