My dolgo seedling fruit, depending on the tree, is red, orange, yellow or nearly black when ripe. The fruit size ranges by tree quite a bit. The taste, by tree, ranges from bland to extremely astringent. The drop times, by tree, are anywhere from about late September to midwinter, though in some years the midwinter ones drop around Thanksgiving instead. I've been thinking that the droptime variability of a given tree may be due to differences in soil moisture year-too-year or it might have to do with growing degree days (that is, did they get fully ripe and then drop versus eventually fell off even though they were less than fully ripe). Most of them have extended bloom seasons, so they are good pollination partners for the other apple trees around. Some grow very vigorously. On the other hand, I had a couple get only five feet tall, grow their branches in a spiral configuration, and grow thorns. I cut those down when they were about 20 years old after nothing I did to try to train them worked.
