How do I do a culture test on maple trees in my area that may have this fungus (tree leaves browning and wilting severely despite adequate watering)? Thanks.

Verticilliuim wilt can be positively identified by submitting samples to the University of Illinois Plant Clinic. You will need to contact a county extension office to obtain a plant clinic submission form or at http://plantclinic.cropsci.uiuc.edu/submit.html, look on the left had side.

Suggestions from the Plant Clinic site include: Collect fresh specimens. Send a generous amount of material, if available, during the period the Plant Clinic is open, May 1 thru Sept 15. Ship in a crush-proof container immediately after collecting. If holdover periods are encountered, keep specimen cool. Mail packages to arrive on weekdays. Avoid weekend lay overs.

In the case of V. wilt, a sample containing sapwood discoloration is key. The disease typically moves up the trunk and into the branches. samples taken at the trunk, lower on the tree should contain the streaking in the sapwood.

If you have V. wilt, you will need to avoid planting trees that can contract the fungus as well.

Hope this information is useful.

Sincerely, Richard Hentschel