I have discovered what looks like bora on our nectarine tree. We treated our house for bora last summer. Could the bora have spread from the house to this fruit tree? How can we treat it so the fruit will be safe to eat?
You will be relieved to learn that the borer (also known as bora) has not spread from your house to the tree. Numerous fruiting and non fruiting trees can unfortunately be affected by tree borer.
Where possible on your nectarine tree, remove the limbs with the obvious signs of borer. However if the borer has infected major branches, it will be necessary to use a horticultural insecticide which has been specifically developed for borer (your local garden centre can give you advice about which brand to use). This comes in a small bottle which squirts into the borer holes and then seals them. This is quite effective in killing the borer and will in no way affect the quality or influence the taste of your fruit.
In some gardens you will find very old trees heavily affected by borer, these should be chopped out and removed from your garden otherwise they will become a host plant from which the borer will spread to other trees in your garden.