We have had several cases of oak leaf tatters at the Plant Clinic this season. When a diagnostician labels foliage as “tattered,” he or she is referring to the battering of wind on desiccated leaf tissue. Foliage may have been desiccated by wind, sun, or lack of water absorption. The result is a tattered appearance. Oak leaf tatters is a bit different scenario.

Try to picture foliage with a lack of leaf tissue, with only the major veins and a bit of tissue around the veins. That is oak leaf tatters. Leaves appear to have been eaten by something that avoided the veins. We have seen this problem on white oaks for at least 15 years in Illinois. It has been reported in other states as well, including Iowa, Indiana, Ohio, Michigan, Wisconsin, Minnesota, and Missouri.

No disease problem has been implicated. Likewise, insects are not the cause of oak leaf tatters. For many years, suspect causes included environmental stress as leaves emerge, cold damage, and herbicide drift. Last year, three researchers at the University of Illinois did a preliminary study that indicates that drift of chloroacetamide herbicides from applications onto corn and soybean fields is a possible cause of the leaf tatters syndrome. The researchers are Jayesh Samtani, John Masiunas, and Jim Appleby. An article describing their work can be found in the Plant Health Progress On-line Journal, February 2005, at http://www.plantmanagementnetwork.org/sub/php/brief/2005/tatters/.

White oak is the common oak species affected. Many of the trees with oak tatters are affected early in the season but produce normal leaves later in the season. There has been some concern that a tree repeatedly attached by oak tatters might decline and even die. No evidence exists to confirm this theory but the question merits investigation. You may help your trees by following good horticultural practices to promote tree health, especially watering in periods of drought stress.

Some questions and answers about this problem are listed at http://www.extension.uiuc.edu/mg/oaktatters.htm. This site was developed to assist Illinois Master Gardeners in identifying suspect trees. Photos are posted as well. Another helpful site is the U.S. Forest Service pest alert about tatters at http://www.na.fs.fed.us/spfo/pubs/pest_al/oaktatters/oaktatters.htm.