Some links and a PDF.
Doesn't appear chemicals will be effective and may knock out the good guys too. They talk of some biological control fungus.
If you look at chemicalcontrolsforeucs PDF there's some mixing ratios ... in the Dimethoate row is the ratio for mixing for stem injection. Note the ratio is 50/50 chemical to water, however note you should be using Maldison and there's no mix ratio for injection.
Over here there's many "no mix" ratios for injecting, like unconquered ground! But if you look at the Dimethoate ratios for foliage spray vs injection you'll see the similarity ... so what I'd do is mix it 50/50.
red gum ecosystem: predator prey Gum Leaf Skeletoniser