Plant Doctor Archive

Scale insects

WE have had a really bad infestation of scale this summer. It took me a while to realise what was happening, and as a result, we lost three pittosporums - two young plants and one tree that was 2m tall. We almost lost a lillypilly tree as well, but after a harsh prune and lots of spraying, I think we are getting on top of it. My question is, how do I ensure I get rid of it all? And is there any way to stop it happening again? I find your column very helpful - and as a new gardener, I need all the help I can get.

SCALE is a real threat to plants if the infestation is severe. You are on the right track though, by pruning the trees to thin them out and get more air circulating. Make sure all of the clippings were removed or burnt, as the insects will travel onto other plants from your prunings.

Continue spraying until you have eradicated the pests and make sure to alternate your insecticides. Use Yates Orthene, Conqueror Oil or Confidor and use the spraying oil at either its winter or spring strength when needed. Orthene and Confidor are systemic, whereas the Conqueror Oil will smother the insects.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.