The most common fruit tree diseases are fire blight, apple scab, fly speck, sooty blotch, pear scab, cedar-apple rust, bacterial spot, brown rot and powdery mildew.
You will be able to spot these diseases with signs such as fruit discoloration and the leaves and fruit falling off the tree as happens with scab and bacterial spot. Powdery mildew leaves a film all over the fruit, as well as on the leaves, branches and twigs. Brown rot leaves pitting and spots all over the fruit.
With diseases such as sooty blotch and fly speck, there will be extreme discoloration of the fruit, the limbs and leaves. Also, these two diseases many times appear at the same time. They are usually only found during the summer months when there has been heavy rain and high temperatures.
The effects of all the diseases on your fruit trees will mean the potential for the tree to die. Initially, there will be less fruit each season, new twigs will not grow, leaves will continue to fall off and branches will rot along with the fruit.
If your fruit trees have become infected, remove all damaged fruit, twigs, leaves and branches immediately. The sooner you dispose of these infected parts, the less chance there is of the diseases spreading from season to season.