But you know I’m gonna be that garden designer and horticulturist who will explain why, why, why, this rather seemingly obscure disease needs some reckoning.
I pursued the ahem, “root” cause of the Wilt and didn’t just look for a treatment (as elusive as that is), and at the same time, my curiosity fueled my next steps. I researched, discovered, theorized, and then test-drove my assumptions with a soil expert.
I believe we can all learn from this case study of a Duchess Designs’ client story issue. And we can learn oh-so-much learn from the brilliance of the renowned soil expert, George Lozefski, who is the Field and Education Outreach Coordinator at the Urban Soils Institute, and who also is a School of Professional Horticulture instructor at The New York Botanical Garden (NYBG).
See, while I’m getting a wee bit ahead of myself, it helps to understand that ever since a wonderful new client this season asked the Duchess team to work for him and his family, the old maple tree in the front yard that was recognized and beloved by generations was a paramount concern. He told me his daughter loved to climb in the tree -- he shared a photo of her taking one last climb up into the limbs’ embrace (just like I did as a kid, I’d sit in the crotch of my favorite backyard tree and read.)
Client's sweet, tree hugger daughter enjoying a last climb in the tree. (I drew the heart on her face to protect her privacy)
And while me and my Duchess Team were prepping for the removal of the tree,
|Duchess team, Julie & Darin relocating perennials as part of tree removal prep
a young man stopped to say he’d grown up in the house and loved climbing the maple tree all through his childhood. Oh, the fun... The shade for the house, the beauty of this old soul…
When I was first was called in to scope out the property for the gardening and horticulture work, the owner, Bob, and together we walked the yard and ended the tour at the tree. He asked, “Is it dead?” It broke my heart to point out that with no leaves (and it was early summer) that yes, regrettably, the tree was dead. Initially I was convinced that the tree was damaged and compromised by the heavy machinery that was on-property during the home’s renovation. Most folks don’t realize that repeated, sustained construction driving around a tree’s roots leads to compaction from those trucks, tractors, or equipment within the root zone that compresses the trees’ pores and cuts off oxygen. I’ve seen this happen with pool or patio installations. Then there is the issue of paint, cement, or siding plaster rinsed out over roots… There’s no end of the environmental damage that can occur during a home renovation or construction.
My research reinforced the fact that, of course, roots are one of the most vital parts of the tree. “The roots are responsible for nutrient, oxygen and water uptake and anchoring the tree in the soil. In addition, energy rich chemicals are stored in the roots. Trees draw on these energy reserves to get them through emergencies like drought, defoliation, insect attack or construction damage.”
So the root and compaction was the first of the 0ne-Two punch. Or the One-Two-Three punch-fest! I figured the tree might’ve been compromised from the equipment but I also thought that the strong tree could have been able to bounce back. Moreover, this kind of construction damage can take years to manifest itself. That’s why homeowners usually will blame the tree’s death to something else and unrelated. So what took advantage of this beloved tree?
Soon, I was connecting the dots.
While everyone, including me, couldn’t help but admire the client’s country-club green, thick lawn, I also know that it takes a lot of chemicals to achieve that emerald carpet. A lot. Further, this lawn was not laid in with sod but rather with the Power Seeding method. There is also the Hydro Seeding, Slice Seeding, and Overseeding.
One company I found online even recommends that “In the same way that a farmer plows and turns over a field every year, your lawn needs to have the soil conditions enhanced through aeration.” While part of that is true in terms of aerating the soil;
suffice to note that all this power blowing of the seeds into the soil, also helps destroy the soil structure, George Lozefski explained to me later.
This lawn seeding approach helped fuel the disruption of the symbiosis between the soil and the tree. George pointed out that blowing in seeds most likely helps destroy the soil structure. “There is a very thin layer of turf to topsoil layer that fungus and bacteria can infiltrate,” said.
Here, I’ll flash forward to the day the arborists came to take down the grand dame, maple tree.
Bob’s daughter asked if we could save some trunk pieces for her - she would later create a memorable homage from the two handsome pieces I selected for her. What a lovely garden sprite she is.
On that auspicious day, the skilled arborists worked their artful craft. Soon, all that remained was the stump that they then began to grind.
But before they could finish that, the cutting away revealed something. The owner of the tree company called me over.
He wanted me to see what he was seeing.
There was something visibly brown in the tree trunk. There was no getting around it. We could readily see it was Verticillium Wilt.
Afterwards, I began my research on the Wilt in earnest. I wanted to understand what environmental elements could triangulate at such a deadly crossroads.
Or as Mary Ellen Salyan wrote in her paper on soil-borne pathogens for the Master Gardener’s WSU/Skagit Co. Extension Office, Washington: “In order for (soil) disease to exist and thrive, the exact environmental conditions, in concert with a host and a pathogen, must be present simultaneously.”
I learned that the fungus can be transmitted to garden soil infected from a few sources. Once the fungus is in one location, it can be easily spread in the soil via tilling, digging, and moving soil around in any other way, and by water and wind.
Remember all that power seeding and hydro seeding and slice seeding jettisoning grass seeds into the newly aerated / disturbed soil? That act sets up the soil for problems. Then, lawn care companies use nitrogen-rich fertilizer on the lawns. Undoubtedly, nitrogen gives a powerful growing boost, making the grass grow quickly and become a deeper green.
Even some starter fertilizers contain two parts of nitrogen and one part of phosphorus and potassium. The N-P-K rating many lawn-care companies recommend for grass typically is: Big - Small - Small. They say grass needs a lot of Nitrogen and a little bit of the other stuff. That’s the essence of what some recommend: 21-3-3! That’s a lot of nitrogen! Wow.
All that nitrogen, coupled with the soil disturbance - and the power of irrigation - excess moisture and soil pH are catalysts for these pathogens to thrive - creates a kind of witches brew that is detrimental to soil health.
Further alarming is that our ever-increasing warmer winters here in the Northeast allows pathogens to survive.
While it’s true that nitrogen does indeed turbo-charge the plant’s green and growth, George explained to me that the nitrogen also stimulates the growth so much that it can in turn, weaken cell walls ~ a plant’s stems or walls can collapse, further exposing the plant to pathogens. It’s a kind of horticulture death spiral. George also pointed out - alarmingly, I might add, that Nitrogen that is so key in fertilizers is used in the production of explosives (!). Further, he said that excessive plant growth can cause problems with yields in commercial agriculture. “A good soil is a delicate balance and our job is to maintain that equilibrium,” he added. And it’s so easy to establish and maintain this balance. George explained that soil is the fabric of health improving water and air quality. Don’t disturb the delicate balance… At the same time, he said there is no “Easy Button.” It does take work but at the end of the day, there’s really no other choice.
“There is no less of a concern when George points out that most folks want to hit the “easy button” when it comes to maintaining good soil health. “Weeding is work,” he says. Tell me. Me and the Duchess Designs team weed more than ever. :( The mow, blow and go guys spread the invasive “lawn” weeds on their mowers, blow into the ornamental and edible garden beds. And don’t get me started on the invasive vines that creep, crawl, take over, and overwhelm homeowners to the point where they bring us in to mindfully weed out. Yes, it takes work but you can just spray your way to garden health. There’s just no excuse for poor land management, George says.
The Link from the Soil to the Tree
In a nutshell, Verticillium Wilt is a “serious fungal disease that causes injury or death to many plants. It is a disease of the xylem, or water-conducting tissues, in the plant of more than 300 plants, including woody ornamentals, most noticeably elms, magnolias, maples, redbud, and viburnums. Caused by the soil-borne pathogens Verticillium dahliae and V. albo-atrum, these wilts are prevalent throughout the tropical and temperate regions of the world. They exist in the soil primarily as mycelia that infect belowground plant tissue.”
Soil borne pathogens - whether pesticides or herbicides - are an overapplication of chemicals, explained George. “Soil-borne pathogens prefer to live within the soil, causing root disease.”
Symptoms of Verticillium Wilt vary somewhat in different host species and also within species due to varying environmental conditions. These might include sudden wilting of small branches, yellowing of foliage, stunting of growth and premature defoliation. Vascular tissue appears as a dark ring in cross sections or pin-point dark spots.
Verticillium species are opportunistic fungi that persist in the soil as saprophytes. The organism overwinters as mycelia or microsclerotia, a dark, condensed mass of mycelium that collectively acts as a propagule, which germinates under favorable conditions. Infection begins in the root area where the resting hyphae of Verticillium germinate and penetrate feeder roots. The fungus also can enter wounds in the root area. The disease spreads within the plant by mycelium or spores called microconidia that travel in xylem vessels to other parts of the plant. Where the spores lodge, new hyphae grow and increase the infection. The infected plant tissue becomes necrotic (dead) because the vascular tissue is clogged with mycelium, conidia and by-products of fungal metabolism. It’s like having mushrooms block the plant tissue! As a result water flow is restricted and the plant wilts. In the plant, the fungus moves upwards and plugs the vascular system of the plant that is responsible for transporting water. It’s the plugging of the vascular system that causes the typical wilt, and eventually leads to plant death.
The necrotic tissue is what causes the dark streaks that are symptomatic of this Wilt disease.
Integrated Pest Management Strategies
1. Sanitation. Remove affected annuals and perennials or prune damaged areas of trees and shrubs. Pruning disease-damaged branches and foliage plus increasing the vigor of trees and shrubs may help to keep symptoms checked. Be sure to sterilize pruners between cuts.
2. Plant resistant or tolerant species. This is the best way to manage this disease. The fungus can remain dormant in the soil for a decade or more in the form of resting structures called microsclerotia, which survive drought and cold. When a potential host is planted near the microsclerotia, the roots of that plant stimulate the microsclerotia to germinate and produce spores. They attack.In areas that are irrigated, the disease can more readily spread.
While not an environmental requirement for the fungus, stressed plants, often brought on by environmental changes, are easier to attack than healthy plants, so any conditions that will stress the plant but not directly harm it, the Verticillium sees its opportunity and moves in.Treatment
While it’s generally understood that the Wilt is not treatable and fungicides are not generally effective or practical. You can apply a commercial fertilizer that is low in nitrogen, high in phosphorus to help counter balance all that rich, rich, nitrogen that’s been applied. You can also look to solarization; utilizing the sun to help burn out the fungus. You can also plantgroups of plants that are resistant to Verticillium Wilt including, gymnosperms, monocots, members of the rose family, oaks, dogwoods, willows, rhododendrons, azaleas, and others.George noted that the biggest environmental impact of pathogens - the overapplication of chemicals, is the toxicity level in water. The pathogens deplete oxygen levels; kills algae and fish; Phosphorus gets into the groundwater and damages oh-so-much. Eventually, that ecosystem is eventually destroyed.
I’m stepping up onto the soapbox now!
We need balance! Please practice conservation and sustainability. We need to utilize more of our native plants and create a native biodiversity to help fend off the soil borne pathogens.
Good gardening and horticulture is a mix of science and art. Artful lawn care is a mix of science and horticulture. Just think of all the elements in the yard and/or garden as part of the whole cloth - not a list of separate items managed as vertical silos. Further, because our suburban and estate gardens are not islands - distinct from the neighborhood, George shared with me a working example of the perils of not practicing good home maintenance. “Say there are two estates or homes (for those of us on the more modest scale!) on the same side of the street, one kind of below the other,” George said as he laid out the scenario. The homeowner on the down side is practicing good regenerative farming or gardening, using non-invasive plants but then the homeowner on the up side is practicing environmental pollution, i.e. overapplication of chemicals, downstream water toxicity and more. Further, he adds, too often the chemicals are applied in huge quantities. So you can readily understand the result - the good homeowner suffers because of the other…
What to do about Establishing and Nurturing Good Soil:
Take a baseline soil test. If there’s no evident problems, George suggests repeating the soil tests every couple of years to determine the quality of the soil. For edible and for turf, you want to calculate how much lime and nitrogen is present. You can send the soil sample to your local land-grant universities including Rutgers, Cornell, or UMass here in the Northeast US. Others can call and ask your local universities.
Curiously, there is no test available for pathogens… I see opportunity here for someone to come up with such a test. I’m hoping that George’s Urban Soils Institute might come up with such a test. And one for plant tissue testing, while they’re at it! In the meantime, he recommends that if you are growing edibles to do so in raised beds.
“Whether it’s your backyard or the forest, it’s a huge problem,” claims George when discussing the big picture of good soil management and not practising regenerative gardening. Lack of a plan and its execution exacerbates or accelerates the problems. I advocate that in suburbia, homeowners need to be more mindful of their gardens and landscapes. I recognize that the aggressive approach of chemical treatments appeals to the short term or “easy button” that George characterized. However, in the bigger picture, long-term solutions are indeed the recognized better land management. And if one doesn’t practice this for the environment, please consider your family, and pets.
The decimation of the soil due to improper watering and chemical over-application leads the plants to become like an addict ~ dependent on these false nutrients. George points out that it’s so very beneficial and truly easy (no easy button needed) to add compost to the lawn to add beneficial fungi to the soil. It’s a natural fertilizer. “Healthy soil takes care of itself,” George reminds us. When I noted that most of my garden design clients probably wouldn’t want to have compost on their lawns, he suggested to add the compost at the end of the autumn season so that not only is it what I suspect he meant as an unobtrusive season but also the winter rains will help store those good nutrients for the spring.
In my own garden talks I advocate for “leaving the leaves” in the autumn. Why every leaf has to be blown off a lawn and out of the garden beds is a mystery at its funniest and a downright shame at its reality. There is just no need to sanitize a garden or lawn like this. Leaves are a free and natural mulch. And the critters that are part of that healthy ecosystem will be forever grateful.
George recommends that when it comes to fertilizer, look to organic nutrients including different forms of organic materials including bone, fish, and blood meal - they are not synthetics and it’s better for the environment, he added.
I further suggest as most horticulturists do, to limit or abbreviate the amount of lawn space. Ask your mow, blow, & go guys to aim the blow out into the lawn vs. the garden beds. Further, ask them to use a mulching mower so that no clippings get spread into the ornamental or edible beds.
Soil is the fabric of health, George reiterated. Think of it as a mantra… Just like our own human guts, we need to have to have the appropriate microbial balance. Get the good fungi!
What to watch that will bring home the magical world of good, non-chemical microbial fungi in your soil? George recommends the Mycorrhiza miracle of Fantastic Fungi. If you think the internet is cool, check out this network of plant organisms that naturally benefits us. Here is the link to the magical film's trailer.
And there are two transormative tree books that I highly recommend: The Hidden Life of Trees, by Peter Wohlleben
I sincerely hope that this garden case study can serve as a cautionary tale. It’s a true- life horticultural story that highlights the need to take all factors of a property into account. It teaches us how all elements of a property are indeed connected. The plants are not just tools for privacy ~ although they are masters at concealing. It’s not that the plants are there just for beauty ~ although they provide unparalleled glamour. It’s more about thinking of the plants and yard/property, as part of an ecosystem that extends from your yard to your neighborhood, and beyond. It’s a thinking person’s endeavour. You can do it.
And the glamour of the good fungi? Wow. Dazzling.
* The resources I used for this feature are in quotes and are a result of my extensive online search. Where not cited in the text, I have aggregated the content to make what might be an esoteric or obscure topic more readable and pertinent to you and your gardening professionals. Sources include: The Morton Arboretum, The Missouri Botanical Garden, Garden Tech, and Iowa State University. * The top-rate arborists are Hufnagel Tree Service - I’ve worked with them for many years. Trusted, certified arborists. Thank you, Mike.