Look for signs of two invasive dangers to trees in WNY

Western New Yorkers should watch for signs of oak wilt and Asian longhorned beetles (ALB), two invasive dangers to trees. Neither has been found yet in Western New York, but if either is here, early detection could help stop the spread.

You might also begin to notice tar spot, which is common on maples here. It’s ugly, but doesn’t damage the tree.

Oak wilt

oak leaves showing symptoms of oak wilt
Leaves from a tree infected with oak wilt disease may brown from the outside of the leaf toward the stem. Photo courtesy New York State Department of Environmental Conservation

Oak wilt disease is a fungal disease that affects both red and white oaks, but red oaks (pointy leaf tips) often die much faster than white oaks (rounded leaf tips).

Oak wilt symptoms include:

  • Most or all of the leaves fall off of the tree in July or August.
  • Leaves turn brown from the outer edge back towards the stem.
  • Leaves of all colors will fall off the tree, and many will still have green on them
  • Dieback may be visible starting at the top of the tree and progressing downward.

DEC tracks and manages oak wilt disease in New York State. If you see these signs on an oak in July or August, contact DEC’s Forest Health team for confirmation.

Asian longhorned beetle (ALB)

Asian longhorned beetle in pool
Check you pool filter periodically during August for the invasive beetle called Asian longhorned beetle. Photo courtesy Jessica Cancelliere of NYSDEC Forest Health Program

People who have swimming pools can look for Asian longhorned beetles (ALB) in their pool filters during August.

ALB are about 1.5 inches long, black with white spots, and have black and white antennae.

DEC is asking swimming pool owners to periodically check pool filters for insects that resemble ALB and report suspects either by emailing photos to foresthealth@dec.ny.gov or mailing insects to DEC’s Forest Health Diagnostics Lab at 108 Game Farm Road, Delmar, NY 12054, Attn: Jessica Cancelliere.

People without swimming pools can help the effort by reporting signs of ALB in their communities. With more people currently staying at home, it is a good opportunity to pay closer attention to yard and neighborhood trees.

The ALB leave perfectly round exit holes about the size of a dime in branches and trunks of host trees. They also create sawdust-like material called frass that collects on branches and around the base of trees.

These pests attack a variety of hardwoods, including maples, birches and willows, among others, and have caused the death of hundreds of thousands of trees across the country.

The New York State Department of Agriculture and Markets worked diligently to manage ALB infestations in other parts of New York State, successfully eradicating them from Brooklyn, Staten Island, Manhattan, Islip, and Queens. The beetle is still actively managed in central Long Island, and there are active infestations in Massachusetts, Ohio and South Carolina.

See more information on the ALB Pool Survey and ALB, including biology and identification tools.

Tar spot

tar spot on maple leaves in Western New York 2014
Gardeners often notice tar spot on fallen maple leaves in autumn. Photo by Connie Oswald Stofko

You may be noticing black spots on your maple leaves, but don’t worry. Tar spot is a fungal disease that resembles splotches of tar on leaf surfaces, but it is mostly just a cosmetic nuisance. Heavy infections may cause early leaf drop, but the fungus does not cause long-term damage to the tree.

See more about tar spot in this previous article.

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