I have two Pawpaw-trees in Vienna/Austria. They are now 14 years old and one of them, a "Sunflower" does quite well. It is about 4m high. The other, a "Overleese" grows very slowly (it is less than 2m high) has yellow leaves and gets brown, dry stains in July. There are only 3m between the two trees so there should not be much difference in soil quality. Any idea what causes yellow leaves?
/Robert