Emerald ash borer, sudden oak death, Dutch
elm disease, oak wilt disease, walnut canker,
hemlock woolly adelgid—in a globalizing world,
many trees are facing pandemics of their own.
And now climate change, with its catastrophic
droughts, floods, and heat waves, is making it
especially difficult to fight off attackers. Even
Joshua trees, icons of the southwestern desert,
are finding that the world is too warm.
All this has led some scientists to ask: Can
we build better trees, ones that are more able
to cope? And here again the American chest-
nut may soon set a precedent—this time on
the path to resurrection. By tweaking its DNA,
scientists say, they’ve created a blight-resistant
tree that’s ready for a second act. If it works for
the American chestnut, perhaps it can work for
other similarly afflicted trees.
“Some people say, ‘You’re playing God,’ ” says
Allen Nichols, president of the New York chapter
of the American Chestnut Foundation. “What I
say is: We’ve been playing the devil for ages, so
we need to start playing God, or we’re going to
start losing a whole mess of stuff.”THE CHESTNUT BLIGHT IS CAUSED by an insidious
fungus that leaves orange-tinted cankers on a
tree’s trunk and limbs. These splotchy indenta-
tions, reminiscent of a bruise, can choke off the
tree’s flow of water and nutrients. The fungus,
Cryphonectria parasitica, spares the young. But
as tree bark ages, it cracks, letting microscopicFIXING FORESTS 133