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I have a friend who has a lot of ornamental manuka and most of them are sick or dead because of the blight. I believe it is caused by a scale insect that was deliberately introduced from Australia many moons ago to help control the spread of manuka.

He is looking for a spray to control this problem, preferably non-toxic. Any ideas on whether a summer or winter oil would work.

My father remembers the introduction of this pest and he said that the time it was fantastic because the bees worked clover rather than the normal manuka and they could sell the clover.

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This from Farm Forestry NZ  :     "This insect, an accidental introduction from Australia, is present throughout New Zealand. The blight, first seen in Canterbury about 1937, had by 1948 spread at the most only 145 km from its original place of discovery. During the following 10 years many farmers who regarded manuka as a major weed deliberately disseminated infested twigs. As a result, the scale insect became widespread throughout North and South Islands with consequent death of manuka. 

 

And from the National Library :    The control of this disease on isolated specimens of Leptospermum scoparium presents no difficulty. It has been found that spraying once a year during the winter months with an oil emulsion is sufficient to kill the scale insects. This removes the source of nourishment of the fungus and prevents further growth. It has been found necessary to spray each year as the trees are readily reinfected with coccids. Naturally it would not be practicable to utilize this spraying technique in protecting manuka on isolated hill country where difficulties of access and topography would preclude the use of standard equipment.

 

 

Edited by yesbut
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Yeah nah John ..... let 'er run . Should help to lift the clover price !

 

On a more serious note .... we get the blight here every so often .... it runs through kills some of the scrub , but they seem to get over it.

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