Plant Doctor Archive

Scale insect on Norfolk pine

I HAVE a small Norfolk pine tree in a large barrel on my front porch. I live beside the sea but I seem to have a problem with some kind of scale. My tree is starting to die from the bottom up. The scale is yellow and black in colour and nothing I put on it seems to help. Please help me save my tree - it was a present from my son.

I AM assuming that your scale is the insect variety and not a fungal lesion. Scale can be a real problem if it gets out of control. The types of chemical you need to use are Yates Orthene, Confidor or Conqueror Oil. The first two are systemic, so the insect takes it up when feeding. The oil coats the insect and suffocates it. Reapply the insecticide a couple of times to get rid of the scale completely. Alternating the chemicals is a good idea so that the insects don't build up a resistance. If your scale is of the fungal type you will need to try Yates Bravo or Greenguard. If the fungal problem is a severe case, then the plant may not be able to be saved. Check the drainage and the position the pot is in - it may need to be raised off the floor.

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