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Leaf Spots, Early Fall Colors, Leaf Drop, Oh My! and The Tall Stately Man

By: Anthony Arnoldi, Board-Certified Master Arborist WI-0102B

It has been increasing ever since the middle of summer – trees showing greater and greater amounts of stress as summer has worn on. The number of concerned calls we received inquiring as to the reasons for this have increased right along with these symptoms.

The infection creates dead spots of ever-increasing size as the fungus grows (leaf spots). Other fungi cause similar problems of leaves, but look more like irregular brown splotches of dead leaf tissue (“anthracnose”). Still another group of fungi causes a white film to develop on leaves (“powdery mildew”). One leaf spot in particular, called “Tar Spot” looks quite dramatic on maple leaves and caused quite a stir. It had its “best” year ever and caused a lot of leaf drop in August and September, especially if you lived closer to Lake Michigan. The extra moisture and coolness helped to encourage that fungus even more.

All of these fungal diseases roared along at a record pace until, by mid to late summer, they had caused sufficient damage to make many leaves fall. For some types of trees, such as crabapples showing apple scab defoliation, or hawthorns showing rust defoliation, spray programs are recommended because these fungi cause annual, predictable, heavy EARLY defoliation that weaken them over time. For most others, however, this year was an anomaly, causing heavy defoliation this year only. Trees can withstand a single year of early defoliation without serious injury. This is especially true if the defoliation happens in late summer.  Because of this, spray programs are usually not recommended for many leaf spot diseases. But be careful: we have learned of at least one case where powdery mildew was touted as a deadly disease that would cause trees to die unless immediate treatments were started! (This is not correct.) Be sure you can trust your source of information.

This summer was known for its heat. The heat made for an incubator-like environment that helped grow fungi at an accelerated rate. It also was an additional stress on the trees. This helps explain why leaves were dropped even earlier than would have happened through fungal action alone.

The stresses of the year caused many trees and shrubs to manifest early fall colors. Trees displaying this symptom are surely affected enough to be concerned about. Root rot fungi are often involved in cases like these.

So, what is the take-home message from all of this? First of all, do not panic, nor listen to those who would try to panic you or rush you into fast decisions. Instead, gather all of the relevant facts. Think of how the tree has reacted the last few years. For many trees suffering from a heavy defoliation, it may be a good year to try to relieve stress, and build health. Fall Fertilization, Compost tea, Mycorrhizal root inoculation, and Root Biostimulant therapy can all help do this. There may need to be some detective work to uncover an underlying issue when early fall colors are involved. Always know you can call your Wachtel Certified Arborist to help sort through all of the information and misinformation, so you can make a truly informed decision that can help reduce stress, both for you and for your trees. This is our passion.

By Ellen Filley

As we all one by one arrived at the visitor center of the UW-Madison Arboretum, the promise of a beautiful day was before us. With great anticipation, we looked off towards the parking lot awaiting the arrival of our tour guide. Professor Emeritus Edward Hasselkus (Ed) arrived and walked towards our group. Tall in stature donning a walking stick for today, he promised a lengthy tour of the Longenecker Horticultural Gardens. 

As Ed approached, he greeted us with a large smile and a hearty good morning to you all. Ed was professor and mentor to many from our group who attended studies at UW Madison.

Ed took his place on a bench outside the visitor center and started to tell us his story.   This stately man had just celebrated his 80th birthday, but you would never know it with all of the energy he brought to the stories he shared.  Ed spoke of his love for the Gardens and how it came about that he became curator back in 1966. Retired in 1994, he continues to volunteer as the garden curator. Delight and passion was in Ed’s voice as he spoke of the Gardens and his desire to ensure a fruitful future through the endowment fund he and his wife Betty have started (The Ed Hasselkus Curator Endowment Fund).  Click for link  Wachtel Tree Science presented a generous gift to this fund much to Ed’s delight.

Ed said, “Well, I do believe we came to see the trees. Let us get started”.  With a gentle tap of his walking stick like a wizard, we all followed him to the opening of the gardens. He spoke of the trees as if they were his children. Ed, clearly, recalled the origin and acquisition date of each specimen we discussed.   As we walked through the gardens, he explained the intent of the design. The trees formed walls, creating “rooms” within the gardens. Each room displayed different taxa, such as the 120 different cultivars of crabapples. The beautiful display nature created inspired each of us to want to see more and to hear more of Ed’s wealth of knowledge.

We walked a good part of the morning throughout the gardens and yet, we only saw a small portion of what was there. Without question, a return trip to the gardens will be in order to continue the walk through the rooms’ nature has provided. If you wish to spend a day delighting your eyes and nurturing your mind, please visit the Arboretum. Click for link

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