Oak Wilt: Prevention, Detection, and Action!

Do you have an oak tree in your yard?  A favorite oak tree at a local park?  Or just enjoy seeing the majestic, mature oaks as you roll along a street or country road?  Then help protect them! 

May is oak wilt awareness month!  Oak wilt is a fungal disease that causes oaks’ leaves to turn brown and wilt.  Oak wilt is generally spread in two ways: 1) by sap beetles landing on fresh wounds and carrying fungal spores to other trees or firewood, or 2) underground through root systems to nearby oaks.  All oaks in Michigan are susceptible, but the red oak group, identified by leaves with bristle tips, are especially vulnerable and rapidly succumb to the disease.  Members of the white oak group, distinguished by rounded leaf tips, are sometimes able to recover.  Oak wilt is difficult and costly to stop, so prevention is key! 

To Protect Michigan’s Oaks:

1. Plan to prune oak trees after November 1 and before March 14.  If pruning is necessary outside of the dormant season, immediately paint any cuts with wound sealant or latex paint.  Do NOT prune oak trees during the greatest risk period (April 15 – July 15). 
2. Do NOT transfer firewood!  Moving infected wood can cause new outbreaks.
3. Monitor oaks on your property and in your neighborhood and local parks for signs of oak wilt.  If you suspect oak wilt, contact a professional for help (see resources below) and report to the Michigan Department of Natural Resources hotline by emailing DNR-FRD-Forest-Health@michigan.gov 
4. Report known oak wilt on the Midwest Invasive Species Network website. Reporting allows for patterns and areas of concern to be identified. 

 Monitor for Signs and Symptoms of Oak Wilt

1. Fast leaf shed/drop, especially noticeable during summer months
2. Tanning of leaf tips
3. Branches and leaves sprouting from the trunk or base of the infected oak late in the season or early the following growing season
4. Presence of pressure pads (fungal mats) beneath bark of the infected oak late in the season or early the following growing season
5. Progressive pattern of oak decline or death moving outward in a radial pattern of one tier of oak trees per year from the first infected oak
6. Note: Species in the white oak group may not decline as rapidly, so watch for more gradual changes in canopy density.

If you think you may have oak wilt on your property, do not wait to contact a qualified professional experienced in the diagnosis and treatment of oak wilt disease (see resources below).  Please note, leaf loss, crown thinning, or death of oaks can be caused by other diseases or conditions, so it is best to hire a professional to ensure the problem is addressed correctly and efficiently.  Long live Michigan’s oaks!

Resources

• Oak ID
  • USDA Field Guide to Native Oak Species of Eastern North America (Abbreviated Michigan Version)
• Oak Wilt Information
  • Michigan Oak Wilt Coalition
  • MSU Extension Oak Wilt Disease Article
• Fina A Qualified Arborist
  • Oak Wilt Qualified Specialist Directory
  • ISA Michigan Find An Arborist Tool