Give it another few weeks. Try a scratch test on several twigs/small branches of the questionable ones. If the cambium is still green, then it's more hopeful. Make sure they have water, but don't drown them - and don't feed them either. If the cambium is brown, go further down the trunks/branches until you hit green. You can trim off the truly dead stuff, but be careful not to damage any possibly live stuff - it may be better to wait and be sure it's dead before you cut anything. Cut off the dead trunks at or just below ground level. The tree/clump should have a good root system by now, so if the trunks all are alive, they should go well, once they get going. If the two are dead, and you really want a multiple-trunked specimen, then you can select 2 or more strong suckers from very low on the base of the live one, and let them grow over the summer. Next year, you can select the strongest one(s), and go from there. It will take longer, but you will have a multi-trunked tree.

Had the same problem last year. Called an arborist who recommended 2 types of treatments - One was a simple spray applied twice in the year - early spring and mid summer, and the other was some treatment directly injected into the root zone of the birch. I opted for the second option. It seemed to work BUT I have just noticed a few leaves turn yellow and crinkled again this week ( very very few). However, there are no aphids / black soot like covering underneath them. Guess the treatment is working .. he recommends treatment every year as river birches are susceptible.

I simply love the overall look of 'Heritage' River Birch trees. The 'Dura Heats' are reported to withstand planting areas that drain better and that may encounter more drying out in the hottest parts of summer, when rains are less apt to occur. Personally though, the 'Dura Heat' birches seem to display a little more yellow than I would prefer to see in a birch tree's bark. The leaves also do not seem to be as nicely shaped or colored as the Heritage Birch tree's leaves. Bottom line; I guess whichever birch cultivar you plant needs to the cultivar that is more compatable with the soil conditons and climate that the tree will encounter in its intended planting site. Still personally I prefer the Heritage Birch tree cultivar over most others. There are even prettier cultivars than Heritage Birch, but any those others that happen to tolerate my USDA zone area seem to be more prone to Birch borers or even other pests, which feed off the leaves of such birch trees.

A rust that probably will not be a major problem to the tree. If you need confirmation take some samples of the affected leaves, seal them in a plastic bag, and take them into your county office of your state universities USDA Cooperative Extension Service.