The roses have it too.
This will be relatively easy with some persistence. General fungicides can effective, but neem oil is a good, organic go-to. There are a number of horticultural soaps that can help, as well. Along with treatment, it will be best to keep all infected debris away from the tree as it falls. As well, try and keep heavily infected growth pruned away.
https://www.gardeningknowhow.com/plant-problems/disease/black-spot-fungus.htm
my apple tree is planted very close to a chestnut tree, about a meter away, the apples are very dry and bitter, is this because of the chestnut tree
Yes, planting an apple tree just a meter from a chestnut tree can cause problems. Chestnuts have aggressive roots that compete for water and nutrients, which can leave the apple tree stressed and result in dry, bitter fruit. If possible, consider transplanting the apple tree to a sunnier, less crowded spot with better root space. If moving it isn’t an option, try deep watering and mulching regularly to help reduce stress and improve fruit quality.
This collection of articles will offer plenty of information on apples:
I have had my property for 19 years and this year for the first time there were blooms on a small portion of an apple tree and I can see about a dozen apples growing. I always had my suspicion that this was an apple tree, but no fruit until this year, and why only a small portion of the tree bloomed?? I think the tree was rather young when we got the property, but I didn't think it would take so long to bear fruit. And is there anything I can do for a better crop next year?
It may have been grown from seed. Those trees take much longer to produce and the fruit may not be up to par. If the fruit is satisfactory, you may want to plant a second tree to aid in cross pollination. Fruit trees need sun and water so be sure the tree is in full sun. These articles will help you take care of it:
https://www.gardeningknowhow.com/edible/fruits/apples/no-fruit-on-apple-trees.htm
https://homeorchard.ucanr.edu/Fruits_&_Nuts/Apple/
https://www.gardeningknowhow.com/edible/fruits/apples/pruning-apple-trees.htm
https://www.gardeningknowhow.com/edible/fruits/apples/apple-tree-feeding.htm
https://www.gardeningknowhow.com/edible/fruits/apples/pests-affecting-apples.htm
https://www.gardeningknowhow.com/edible/fruits/apples/common-apple-varieties.htm