What's Happening To Maple Trees?
Fall allegedly arrived at 3:21 p.m. Eastern time Wednesday. Nobody informed the maples trees around our house. Their leaves, brown and gnarly, started cascading to the ground several weeks ago.
The human mind, at least this human mind, has a tendency to default to apocalyptic scenarios. So I grew concerned that something novel and evil was causing the leaf fall. Not space rays, perhaps, but what about climate change? Or a ravenous invasive insect such the emerald ash borer that is systematically killing our ash trees?
So I decided to contact the Cornell Cooperative Extension of Columbia and Greene Counties. They’re located in Hudson, NY. This isn’t the first time I reached out to these able experts. But sometimes their answers are less than definitive because nature doesn’t always operate in black and white. In this case, however, they responded quickly and unequivocally.
In an email Sandra Linnell, the cooperative extension’s Community Horticulture Coordinator, explained, “This year we have been attacked by anthracnose because of the humidity and rainy weather we had early this year.”
Ms. Linnell kindly attached a link to Cornell University’s College of Agriculture and Life Science’s Plant Disease Diagnostic Clinic. I know that’s a mouthful. But when you’re afraid your beloved maples are about to bite the dust you want something that seems official rather than a website whose information is interspersed with ads for baldness cures and erectile dysfunction potions. Or maybe those pitches are only microtargeted to me.
In any case, Cornell says that anthracnose are diseases caused by fungi. They infect the stems, branches and leaves of a wide variety of deciduous trees including sycamores, oaks and maples, though at our house this year’s victims seem to be exclusively maples. The symptoms, most severe in years with extended cool, wet springs as Ms. Linnell indicated, include spots, blotches and lesions that can kill new shoots entirely or cause severe leaf disfigurement. “This is most likely the cause,” Ms. Linnell added, “of why we are noticing our maple defoliation early this year as we normally see the maple leaves fall later in October.”
The good news, apart from the fact that it’s always encouraging to know your enemy, is that anthracnose isn’t a death sentence for your trees, even though large trees, suffering repeated bouts with the disease, can be severely weakened. That, in turn, can cause a noticeable loss of vigor, dieback of large branches and increased susceptibility to insect borers.
Years ago our trees at our house – not just maples but also oaks – suffered a gypsy moth invasion so dramatic that they denuded all the trees of their leaves. You could actually hear the creepy sound of the gypsy moth caterpillars chomping on the leaves and their droppings falling to the ground. What made their behavior especially egregious is that it happened on my birthday weekend in June. I was fully prepared to fall into despair until I picked up the Sunday New York Times Magazine – this was in the days before most of us got our news online – and learned that our stalwart specimens should refoliate themselves, producing a second growth of leaves by midsummer. And they did.
I’m slightly less sanguine about our current onslaught. If wet weather causes the fungi that prey on trees, climate change is predicting that torrential rainfall will become the norm. Also, as the climate warms the ideal habitat for sugar maples is expected to shift northward. But no need to get despondent, at least not yet. Turns out there’s something of a cure for anthracnose. “A suggestion I would make,” Ms. Linnell wrote, “is to please pick up your leaves so the fungus spores don’t spread.”
They overwinter in leaf debris, then produce spores in the spring that air currents carry to young buds on the host tree. So I’ll be raking even more vigorously than I normally do. Besides, raking, at least in moderation is an excellent aerobic activity, beneficial to both physical and mental health. However, I’d caution you to know your limits. Last year my enthusiasm for the project caused me to overload the oceanic tarp I was raking the leaves onto, thereby risking a hernia or heart attack or perhaps some combonation of the two by hauling them down a steep slope into the woods to scatter them. Gravity only helps so much.
I suppose another question anthracnose in particular and climate change in general provokes is: what does all this disruption, invasion and infection mean for fall foliage? While Ms. Linnell wasn’t asked to address that issue the answer is obviously nothing good. If maple leaves whither and fall prematurely they’re not around to contribute their crimsons and golds to the pageant of autumn colors.
But let’s look on the bright side. With excessive raking, they well may be back to their normal glory next year – one lesson you learn if you’ve been around long enough is that no two years are the same – and our oaks seem as robust as ever. If there’s a blessing in disguise here it’s never to take nature for granted. It’s as fragile as it is resilient.
Ralph Gardner, Jr. is a journalist who divides his time between New York City and Columbia County. More of his work can be found at ralphgardner.com
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