These start to emerge in early spring, and its origin points are the leaves. From the leaves it spreads to various other parts of the tree. The effects can be found on leaves, blossoms, sepals, pedicels, petioles and bud scales. As the disease spreads, the leaves of the plant begin to twist, bend and ultimately die. These scabs appear as small light brown spots, and with passage of time, these spots turn black. The occurrence of this disease is very common during the colder months.
This can be counted as one of the most dangerous diseases. It normally occurs in the period of high humidity and makes the tree weak from inside by infecting the bark, and sometimes, the roots.
The black rot doesn't emerge until a few weeks after the fruit matures. These come about as small brown spots on the fruit which expand and darken with time. The apple undergoes constant change of brown and black shades which makes it shrink and become mushy. The fungus not only attacks the fruit, but also the leaves and bark.
Apple Mosaic Virus
The mosaic virus is very common in most apple tree varieties. It starts off by appearing on leaves in the form of yellow or cream-colored spots. Warm weather is extremely conducive for the growth of this virus, and in the summer it turns the leaves brown, after which they eventually fall off.
Cedar Apple Rust
This disease usually afflicts the eastern red cedar apple trees. They thrive mostly in moist weather and spread the spores on the crab apples. This disease causes a rust effect on the entire tree. It starts with orange spots on the trees which are followed by tiny cup-shaped structures on the undersides of the leaves.
Apple trees are not only affected by naturally occurring bacteria, but also by various insects and pests which cause major damage to the tree, if not properly cared for.
- The best possible way to avoid the spread of various diseases is the pruning of apple trees. Pruning ensures that you don't let the disease spread from one part to the other.
- To trap pests like apple maggots, get a sticky trap from the market and hang it on the branches of the tree.
- For all other diseases, try organic pesticides. Diseases can also be controlled by methods of pruning (like we mentioned before) and proper fertilization.