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Disease-Resistant Dogwoods

Recent progress has been made in developing dogwoods that resist disease — especially anthracnose and other fungal attackers. The following update is from Tom Ranney, professor of horticultural science at NC State University, as told to NPR's Ketzel Levine:

It seems we're entering a new era of dogwoods, a plant you might have thought was passe.

In the wild, we're still dealing with the fungal disease, anthracnose, but the big scare of 15 years ago - when the disease threatened vast native populations - seems to have passed. Yes, there's been high mortality in certain areas of the Smoky Mountains, particularly in deep ravines in heavy shade (those are perfect conditions for anthracnose). But elsewhere, for instance in Kentucky, native populations are intact. When plants grow at lower elevations and get more sunlight, the disease is much less of a problem.

Dozens of great new cultivated varieties are now on the market, many with good disease resistant. Elwin Orton from Rutgers U., who introduced the popular Stellar hybrids a decade ago, has recently released the next generation of crosses from his program. I think of "Venus" which has huge bracts, and Saturn' which is very vigorous.

Another plantsman leading the charge in selecting the best dogwoods for gardeners is Mark Windham, at the University of Tennessee. His 'Appalachian Spring' boasts as a parent the lone survivor of a wild population in Maryland's Catoctin Mountains. All the other trees in that area had been either killed or seriously damaged by anthracnose.

Perhaps a bigger problem for homeowners is powdery mildew, which is very aggressive and gets on new growth. The faster dogwoods grow, and the more water they need, the more suspectible to powdery mildew they become. Not surprisingly, the holy grail in dogwood breeding today is cultivated varieties that have resistance to both powdery mildew and anthracnose. No plants yet that have both, but we're closing in on them.