My 3-year-old apple tree gets a soft fungus around the creases of the branches. I have tried a tooth-brush with water and baking soda which only temporally removes this. Any suggestions please?
From the symptoms you describe, it appears you may have an infestation of woolly aphids. On the tree they appear like clumps of cotton wool, however if you remove that, you will discover small white aphid’s in large numbers close to the stem of the tree and in the creases of branches.
The easiest and most effective way to clean up this problem is during the winter months, when one or two applications of lime sulphur can be applied to the entire tree. This should clear up the problem fairly quickly.
It would be worthwhile to also apply good quality horticultural oil at winter strength as a follow up to your lime sulphur spray.
Do not be distressed by the appearance of this problem as it is very common on apple trees, particularly in the warmer, northern parts of Auckland.
After you have cleaned up the problem inspect the tree regularly to ensure there is not a repeat infestation.
Photo Credit: Woolly Aphid image by Stephen Cresswell / bugguide.net