By: Aimee Bingham Osinski
A few years ago Jason Eyster noticed the leaves of oak trees in the area turning yellow rather than the healthy summer green. He noticed that the trees with the yellow leaves were dying and wanted to know why. He contacted several organizations to find an answer. He quickly realized most did not care or have an answer. A collaborative citizen science group was born from this curiosity. He sought others who might have an interest; residents from both Chelsea and Dexter began investigating and researching the issue.
The group identified 52 trees in the area that seemed to be suffering from the same issues. The group contacted MSU and the university sent people over; the DNR and plant pathology, and collected tissue and soil samples. The hypothesis was the oaks were suffering from a disease called iron chlorosis, a form of malnutrition in trees. But according to the samples, there was plenty of iron in the soil.
The group was perplexed. Why would this problem start happening and why now?
The group consists of a variety of people with a variety of backgrounds; chemists, photographers, school children, and physicians. Someone in the group brought up the question of acid rain. Could it be an issue of acid rain? Acid rain killed half the Black Forest in the 1990s. But when the group found the research and trends in acid rain, it found acid rain has improved greatly in Michigan. Acid rain isn’t killing the oaks. In fact the group discovered that acid rain had likely been helping the oaks. The soil in this area is very alkaline. According to Meagan Shinn of Horticulture Magazine, “On alkaline soils certain nutrients, particularly iron, are locked up.”
Ironically, acid rain neutralizes the soil making the iron more readily available to plants. Due to improvements in acid rain, plants in Michigan are having a difficult time obtaining nutrients. People in agriculture may already be aware. The group spoke to a company that provides fertilizer to farmers. The company explained that farmers of certain crops are having to supplement iron when in years prior the need was not there.
But, iron chlorosis is still a theory. Always curious, the group sent samples from four trees. Three were yellow and the fourth was green. If the theory was correct the trees suffering from iron chlorosis, yellow leaves being a symptom prior to the death of the tree, would have low iron levels. But, the tree with the green leaves had less iron than all the yellow trees.
The group, with a wealth of knowledge and backgrounds, including Professor emeritus George Hochmuth, Plant Nutrition and soil Fertility, The University of Florida, was invited to speak but opted to continue to work with the group because nobody else is really studying the subject at this point. The knowledge gleaned could be potentially groundbreaking, not just for Washtenaw County Oaks, but possibly in different parts of the country and world.
The expert from Florida suggested the group test whether or not the issue is iron chlorosis or if it might be manganese chlorosis. The group plans on testing by utilizing a foliar spray method that a backyard gardener might use on tomato leaves.
However, foliar sprays only work on the leaves sprayed. So, as a true solution for oaks it probably is not the answer. But the group can test leaves for iron and manganese and come up with a plan or a protocol to address the issue. What started as simple curiosity and a collaboration between a variety of backgrounds , is turning into a groundbreaking community science group. Residents of both Dexter and Chelsea are working together to search for answers and solutions.
Between the overall curiosity, and unwillingness to take not sure or shoulder shrugs as an answer, a group of neighborhood scientists might be coming up with a way to save the beautiful old oaks the area is known for.
https://www.hortmag.com/gardens/plants-for-alkaline-soil (link to the article quoted in the story)