Growths on apple tree bark - disease or pests?
By Anfieldjet
Cheshire,
United Kingdom 
I have an apple tree in my small garden. I have noticed this week that one or two branches have developed patches of small, warty-looking brown, soft bumps - a little like blisters. They are about the same size and shape as a ladybird. They are on the bark, not the leaves or fruit. If I rub one of them off to inspect it, it has a white powdery content. Should I be worried? Does it need treating? Thanks.
4 Jun, 2013
Answers
Photo added - I hope that is helpful.
4 Jun, 2013
yes it is scale insect. follow owdboggy advice.
4 Jun, 2013
Thanks both - much appreciated. Are they actually harmful to the tree or is it just a convenient nesting spot for them?
4 Jun, 2013
They are sap suckers and have been known to introduce virus into the tree, so yes they are damaging. In the sort of numbers which may develop they can kill a tree.
4 Jun, 2013
Pick on them now! By hand!
7 Jun, 2013
Previous question
« Self seeded from ??? Lovely bright flowers but what is it please?
Sounds like one of the scale insect types, possibly Oyster scale. A picture would help identify better.
If there are only a few then dab each one with a cotton bud dipped in Methylated spirits. If there are a lot then you need to get some Horticultural soft soap (easily available from Garden Centres) and wash the tree down with it and a soft scrubbing brush. Ordinary insecticides do not work as the insects are waterproof, which is why you need the soap.
4 Jun, 2013