Feral Apples

Some of the comments on an earlier post expressed an interest in "feral" or semi-feral apple cultivars.

The hope is that the feral trees might be well adapted to the stresses of the local environment and be "easy-keepers".

The area designated with "1" is the coldest area since the moderating effect of Lake Ontario projects eastward.

Daniel Cronin, a grad student at University of Guelph wrote a thesis in 2018 that explored the genetic composition of five, widely separated feral apple populations in Ontario, Canada. Before you get too excited, four of the five populations were in Ontario's banana-belt and their minimum winter temperatures are actually warmer than Eaton Rapids, Michigan. One of the feral populations, though, is in an area that is significantly colder.

Census of apple cultivars in commercial orchards near the feral populations. McIntosh, Honeycrisp and Empire are considered cold-hardy. Gala, and Golden Delicious are considered tender.

Somewhat unexpectedly, the genetic composition of the feral trees is significantly different than what is currently grown in commercial orchards near those feral populations. 

Probable parents of feral trees at two different confidence levels

It was not possible to determine the parents of the majority of the +400 feral trees sampled. Several reasons are possible. The trees might be second or third or fourth generation from "known" cultivars. The parents might be obscure varieties that were not base-lined.

Specific crosses

Image from Fedco Seeds. Tolman Sweet was popular for making dried apple slices.

 

Wealthy apple. Image from Orange Pippin Fruit Trees. A parent or grandparent in most of the University of Minnesota breeding program releases.

The highest-runner cross is Wealthy X Tolman Sweet apple. It is a cross that is quite unexpected. Certainly, it is not a cross that a professional apple-breeder would make. Wealthy blooms early while Tolman Sweet blooms late. Both apples are exceptionally cold-hardy. Both apples are susceptible to fire-blight. Both apples tend toward heavy crops. Both apples tend to be considered as second-rate for quality although Tolman Sweet has a small but exceptionally loyal following of people who consider granulated sugar to be extremely unhealthy. 

If a fellow wished to generate very large numbers of seedlings of this cross, he might graft the Tolman Sweet on the southwest side of the tree and the Wealthy on the northeast side. Warm springs tend to compress the flowering cycle and you would end up with a lot of Tolman Sweet (seed parent) x Wealthy (pollen parent) crosses. You could mix antifreeze-and-water so it froze at -40F and chill it with dry-ice. Then you could sort one-year-old, dormant seedlings for cold-hardiness by dunking the tops in the -40F bath for 10 seconds and you would be off to the races.