Maybe can find out from Maryland Cooperative Extension, or Extension in a nearby state.

But it still comes back to choosing ones seen to be resistant in your region, after being grown there, with what, specifically is afflicting the older, obsolete cultivars being secondary - look for flowering crab-apple trial reports that apply to your area, I know I have seen ones from back there on the web in the past.

Fireblight was a BIG problem here last year. We have tried several cultivars over the last few years, canker, and then last year combined with FB has resulted in removal of all but one tree. That one tree will get a chance this year, but we will see how things develop. If we have to remove it, then we are done with crabapples due to disease problems.

Additional note. Trees that appear healthy through spring, and then suffer an overall defoliation likely is due to Scab. FB takes out branches/shoots, while Scab basicaly accumulates on the leaves over time, until they are aborted.

Arktrees