Verticillium Wilt

It’s hard to miss this disease once we enter the hot dry months of summer.  Without fail, each July/August I start to see trees turning brown and wilting suddenly, usually in patches within the canopy that can be traced back to entire individual limbs that have died.  More dramatically, an entire tree will just turn brown and wilt. The pattern of wilting is very regular, and the symptoms can carry over into winter because the wilted leaves sometimes stay on the tree well after normal leaf drop in the fall.

Verticillium Wilt (VW) is easily recognizable once you know what to look for, but not easily treated.  To make matters worse, it affects a large number of trees and plants, with varying expression of symptoms from tree to tree.  During my years as an arborist, I have found Norway Maple, Japanese Maple, Yellowwood, Smoke tree, Redbud and Magnolia to be very common hosts of this disease.  And this is a short, short list of the plants that can be affected.  

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Dead Sugar Maple, suspect VW due to suddenness of wilting

The disease is caused by a fungus present within the soil, and there are so many ways it can get into the soil that my approach is usually “if there is soil present, there is probably VW present”.  What do we do? It sounds like a copout, but the best answer for dealing with this issue is the best answer for dealing with most plant pests and diseases: Choose the right plant for the site conditions. This is the best way to cultivate healthy plants that can naturally cope with the more problematic neighbors within an ecosystem. But this doesn’t really help the tree that has already been planted and is making do with what it has.

If the tree has already been planted, the next best option is to do everything possible to manipulate conditions at the planting site to minimize stress factors to the tree. Ensuring proper moisture, adding organic mulch matter, amending soil both chemically (fertilization if needed) and physically (soil aeration/relief of compaction) are all good measures that can be taken.  There are systemic fungicides that can be applied to suppress the development of the disease within the vascular system of the plant as well, but these applications should be secondary to the site work.

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Dead vascular tissue in Sweetbay Magnolia characteristic of VW

The fungus can enter the tree by wounds in roots but can enter roots even when no wounds are present. Once in the tree, the disease tends to progress upward and outward, causing foliar wilting and dieback to varying extent.  I have seen trees coexist with the disease for years and years, seemingly keeping up with the disease, losing a branch here and there, but generally coping with it. On the other hand, I have seen trees decline quickly. I recall one Sugar Maple which barely had any symptoms until it wilted from head to toe and died over the weekend.

In closing, I feel that VW is an example of how trees really die. There are questions that need to be asked, such as “Was it just a super-virulent strain that entered the tree?” or “Was it a weaker strain, but the tree was just weakened by multiple other factors?”. Sure, there may be cases where everything is perfect for the tree, but the disease was like The Terminator -  unstoppable. In my experience though, most trees die because something else has made them vulnerable and weak enough that a relatively low-grade disease is what finishes them off.  In that case, treating the disease is a last-ditch effort that can only really work if the treatment keeps the tree alive long enough to benefit from the effects of cultural changes that should be implemented if possible.

I think there is a life lesson that can be applied here, but I will let the reader sort that out. Have fun out there!  For every wilted leaf, there are 100 other green ones.

Your friendly neighborhood arborist, 
José Fernández
ISA BCMA® OH-5129B

Our Safe & Drug-Free Workplace

From day one, Russell Tree Experts has always held safety to the highest regard. Each week we dedicate time to train, educate and discuss the most efficient production techniques focused first on safety. Managing a business in an industry recognized by the Bureau of Workers Compensation (BWC) as one of the most dangerous occupations in Ohio, our approach is serious. Not only do we focus on hazards relating to occupational safety, we take it one step further by providing training and awareness regarding issues hard to recognize and not always apparent, but certainly gaining much attention in our society.

Dyann McDowell of Training Marbles

Once a year all 31 Russell Tree Experts crew members gather together to focus specifically on drug and alcohol safety. Last week, before the regular day began, we invited an expert in substance abuse to educate all employees and provide supervisor training pertaining to drug prevention and problems associated with use and misuse of drugs and alcohol in the workplace. Dyann McDowell of Training Marbles (associated with the Ohio BWC Drug-Free Safety Program)  led us through real-life scenarios of how to recognize addiction and how to act swiftly to maintain an environment safe for ourselves and the public. She provided in-depth descriptions of common drugs and those just gaining momentum. She explained historical trends in drug use and current data on where specific drugs are prevalent. She went on to explain how an overdose physically occurs in the body and why it is so hard to reverse. She offered many resources dedicated to rehabilitation for those suffering from drug or alcohol addiction. Supervisors broke out into a small group after the main presentation to further discuss the importance of being aware of the warning signs of substance abuse, how to handle rumors of abuse and when and how to take action.

By participating in the Drug-Free Safety Program, facilitated through the BWC, I am confident our company is smarter, stronger and safer because of the deliberate time we choose to make ourselves aware of the dangers associated with drug and alcohol abuse. I am proud that as a team we are watching out for the wellbeing of our fellow coworkers, to stay safe and make certain everyone returns home healthy and well each and every day.

At the end of the program, all 31 of us participated in drug and alcohol testing administered by a third party organization. I am happy to report we all passed and Russell Tree Experts is 100% Drug and Alcohol FREE!!

Shari Russell
Member, Co-Owner
Russell Tree Experts

The Importance of Green Leaves

Chlorosis in a River Birch causing a die-back in the canopy. ©Russell Tree Experts

I have been noticing what I consider to be an unacceptable amount of chlorosis in urban trees around Columbus. In general, chlorosis is the yellowing of plant foliage caused by a lack of chlorophyll. This is a problem because plants depend on chlorophyll to absorb energy from sunlight and to survive.

Several factors can contribute to the development of chlorosis in trees such as nutrient deficiency, drought, poorly drained and compacted soils, girdling roots, graft union incompatibility and mechanical damage to the tree trunk. For the purpose of this article, I’m going to focus on chlorosis caused by nutrient deficiency because I believe it’s the most prevalent and most often mismanaged. Although any nutrient deficiency could lead to chlorosis in trees, manganese and iron deficiency is what we see most.

Chlorosis in a Red Maple. ©Russell Tree Experts

Chlorosis in a Pin Oak. ©Russell Tree Experts

It is important to understand that the availability of nutrients from the soil can vary with soil pH.  For example, even though there may be an adequate amount of manganese for a certain tree in the soil, the soil pH can cause the manganese to be inaccessible by the tree. Most urban soils in central Ohio are alkaline. (A quick review for those of you who fell asleep in biology, the soil’s pH is an indicator of soil acidity or alkalinity. On a scale of 1-14, 7.0 is neutral, below 7.0 the pH is acidic, above 7.0 the pH is alkaline. Nutrients are most available to trees when the soil pH is between 5.0 and 6.5. Because most of our urban soils have a pH of around 7, we find ourselves dealing with chlorosis.

Initially, chlorosis expresses itself in the canopy of trees by the yellowing of foliage with a network of green veins.  As the chlorosis progresses, leaves become a paler yellow and develop brown necrotic lesions. Leaf margins will eventually brown completely and leaves will dry up and fall off.   Over time this results in poor vigor, reduced twig extension, poor density of canopy, dieback and eventual tree death.

The easiest way to manage chlorosis is to prevent it by planting urban tolerant trees that are tolerant of high pH soils. Although most trees species have the potential to develop chlorosis, the most common trees affected by high pH soils in central Ohio are Pin oak, Red maple, River birch, Shingle Oak, Red Oak, Sweetgum, White pine, and Canadian Hemlock. If you notice yellow leaves on your trees (and it is not time for Fall color) it is important to take action for long-term preservation. 

Russell Tree Experts Tree Wellness Technician Collecting a Soil Sample. ©Russell Tree Experts

The first step is to have a soil and plant tissue test performed. This is the only way to know which nutrients are lacking in your trees and soil. Any attempt at correcting chlorosis without the information from these tests is guesswork and treatment without proper diagnosis is malpractice. We can have these tests performed for you,  interpret the results, and determine the best management for your tree(s).

Just another way Russell Tree Experts is keeping Ohio green!

TJ Nagel
ISA CERTFIED ARBORIST® OH-6298A

Black Knot Disease In Plum & Cherry Trees

©Russell Tree Experts

©Russell Tree Experts

©Russell Tree Experts

©Russell Tree Experts

©Russell Tree Experts

©Russell Tree Experts

Black Knot is a relatively common disease that mainly effects Plum and Cherry trees, but can impact other trees in the prunus species as well. These types of trees can frequently be seen growing in and around Columbus area neighborhoods. Black knot is actually a type of fungus (Apiosporina morbosa). Its characteristic look consists of irregularly shaped black outgrowths arising from tree branches. It often spreads in the springtime but is not noticed by homeowners until winter after the tree leaves have fallen. If left untreated, the black knot growths eventually expand and encase the limbs and twigs of trees and can lead to dead branches, even death of the tree itself. Unfortunately, by the time many homeowners identify this as an issue, the fungus has already critically damaged the tree.

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Early Stages of Black Knot in a Purple Plum Tree in Blacklick, Ohio. ©Russell Tree Experts

It’s best to catch this disease early as this is when it is most easily treated. An early warning sign that black knot may be affecting your tree is the presence of small green swellings/growths on a tree's branches. The first step in treatment is the identification of the presence of the disease. Once identified, selective sanitary pruning of the tree in combination with a fungicide can be instituted.  Unfortunately, if the tree is in the advanced stages of the disease, these treatments may not be enough and the tree may need to be removed. In summary, Black Knot is an important disease that is relatively common, especially in trees types found throughout the Columbus area and is best treated when caught early.

Chris Gill
ISA CERTIFIED ARBORIST® OH-6416A

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If you suspect that your tree(s) may be infected with Black Knot, feel free to give us a call 614-895-7000 or request a free quote!

Witch-Hazel Cone Gall

The photo below is of Witch-hazel cone gall, caused by an aphid bearing the same name.  I find insects that cause galls to be really interesting.  There are many different types, usually host-specific, with various shapes and sizes of galls formed.  In most instances, the feeding of the insect causes an abnormal growth reaction in the plant that forms this gall where either the adult or the immature insect lives inside.  In this case, a single aphid will feed on the leaf in spring, causing the gall to form.  While inside the gall, the female aphid will produce young that eventually emerge in two forms, with two destinies: A wingless form stays on the host plant; the winged form goes to live on Birch trees.  In autumn a second winged generation develops and flies back to the witch-hazel where eggs are laid on the twigs to start the process again the following spring.

When we see galls on leaves and twigs, do we stop to think about the lives of these insects, and the plants that support them?  This world we share is much larger than we realize – it gets bigger the more we look up, or down, and we’re all in this together.

Your friendly neighborhood arborist,

José Fernández
ISA BCMA® OH-5129B

Insect notes summarized from Insects That Feed on Trees and Shrubs, by Warren T. Johnson and Howard H. Lyon, second edition.

Fire Blight is No Delight

As an arborist, I can spot spring coming in February when a faint reddish tinge starts to color the woods.  This tells me trees are starting to stir, and warmth will soon be on its way.  Despite the early clues that I am looking for, I am always amazed by the vibrancy of life once trees have fully emerged.  Yes, I love the stage when trees are flowering, but somehow once trees are fully leafed out they look so alive, so perfect, so unblemished.  No bugs, no drought stress, no fungal diseases – just full, green leaves.

And then… pests and pathogens let us know that they have been waiting for spring as well.  What can we say?  Life the way we know it is varied and expressed by many different forms, each trying to survive in its own way.

This year has been a particularly bad one for fire blight on Pear and Apple trees.  Fire blight is a bacterial disease that affects plants in the Rosaceae family, causing a characteristic blackened wilting of leaves and twigs. This family of plants is also popular for its landscape value, both for flowers and fruit production. Pear, Cherry, Rose, Apple, Serviceberry, Cotoneaster, Hawthorn are just a few trees and shrubs that are very familiar to us. Have you noticed a profusion of dead, blackened leaves in your neighborhood? In your trees?

There are ways to stave off the progression of the disease, even now. Ideally, the trees would be treated earlier in the season for better control, but a combination of steps are recommended for trees that are highly susceptible to the disease. Treatment steps vary depending on how affected your tree is.

Thanks for being our client, and for loving your trees! I’ll see you out there.

Your friendly neighborhood arborist,

José Fernández
ISA BCMA® OH-5129B

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3 Tips to Check for Fire Blight

1. Check if your tree's leaves are browning only at the tips of the limbs

2. Check if limbs have the "Shepherd's Crook" (FYI - The Shepherd's Crooks doesn't always occur in trees infected with fire blight but it an obvious sign of the Fire Blight inspection.)

3. If you suspect your tree has fire blight, please click here or call 614-895-7000 and we'll send a Certified Arborist to review the tree and give you a quote to treat the issue

Watch out Crabapples! Apple Scab is a Major Threat!

Plant diseases love Spring! As temperatures warm and tender new growth emerges, conditions are ideal for pathogens to settle in and take up residence in our favorite trees. It is now when many plants are susceptible and treatable for diseases, such as Dothistroma needle cast of Austrian Pine, Rhizosphaera needle cast of Blue Spruce, rust diseases on hawthorn and pear, and for the purpose of this article: the aesthetically devastating apple scab on flowering crabapple.

What is apple scab and what does it do?

• Apple scab is caused by the pathogen Venturia inaequalis.  It is a common disease targeting the rose family of plants which includes crabapple, apple, pear, hawthorn, mountain ash, cotoneaster and pyracantha.
   

• Apple scab produces lesions on leaves, flowers, fruit and on young succulent shoots.  When infected areas are numerous, leaves can become curled and distorted and severe infections can lead to complete defoliation of trees and shrubs.
   

• Several years of early leaf loss generally results in poor growth, reduced bloom and increased susceptibility to winter injury and insect predation.

How does the disease work?

• Apple scab overwinters in fallen diseased leaves and in the soil.  Disease development is favored by wet weather and cool temperatures that generally occur in central Ohio in the Spring and early Summer.  Fungal spores are moved from the ground and carried to trees by raindrop splash and wind where they make their way to leaves, flowers, and fruit.  
   

• During wet periods, newly emerging crabapple leaves are extremely susceptible to infection.  The longer the leaves remain wet, the more significant the infection can be. 10 - 20 days after initial infection, new spores are released which infect new leaves.  Repeated infections can continue through the summer until environmental conditions become too hot and dry for the pathogen.

What can be done to protect my crabapples?

• For most cultivated varieties of crabapple, fungicides must be applied preventatively to successfully manage apple scab.  Fungicide sprays should begin when the first green leaf tips are emerging with additional sprays being applied in roughly 2-week intervals.  The number of fungicide applications needed can vary with weather conditions but generally, we recommend 3 separate applications.
   

• Other cultural practices that can increase the effectiveness of fungicide applications when managing apple scab are:

1. Raking up and destroying fallen leaves to reduce locations where the apple scab pathogen can overwinter

2. Space crabapple trees generously to increase air circulation around trees

3. Prune out crossing limbs, vigorous upright sprouts and suckers to increase airflow and sunlight penetration into the canopy (this can help foliage dry faster after rain or dew)

4. Avoid overhead irrigation, if plants need water, apply water directly to the root zone.

Additionally, much breeding and selection work has been performed to introduce scab resistant crabapples into the landscape.   A short list of some of the most resistant cultivars includes:

• Coralburst

• Donald Wyman

• Prairiefire

• Purple Prince

• Red Jewel

• Royal Raindrops

• Sugar Tyme

Other common fungal diseases of plants that can be managed through the use of our fungicides include:  Oak Wilt, Dutch Elm Disease, Powdery Mildew, Anthracnose and Verticillium wilt. 

Neonicotinoid Use in Ornamental Landscape and Effects on Honeybees

Neonicotinoids are chemical products that are effective in systemic control of insect pests in plants.  Systemic application of insecticide has multiple advantages over other methods, such as topical applications.  When applied systemically, neonicotinoids are absorbed by the plant, and persist for a longer period of time, so that insect pests subsequently feeding on plant parts ingest the chemical and die. 

Because of this mode of action, there has been concern about neonicotinoids persisting long enough to be found in plant products such as nectar or pollen, where they could be ingested by foraging bees.

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I have been following this topic for several years, collecting various articles that have been trickling in.  As licensed commercial applicators, we are trained that “the label is the law”, so pesticide applications to plants are always made according to label instructions.  However, there have been claims made about neonicotinoids causing problems for Honeybee populations.

I have personally attended seminars here in Ohio where scientists leading research on neonicotinoid use for controlling invasive insect pests have stated that despite some claims to the opposite, there have been “no documented studies” proving a relationship between neonicotinoid use and Honeybee decline.  Since then I have read some articles referring to studies that seem to show a correlation, but no conclusive proof.  As an applicator who cares about the welfare of beneficial insects, the lack of conclusive studies is a source of frustration.  In fact, the approach I was leaning toward was “if there is a high level of uncertainty, perhaps it is best to seek alternatives for treatment, or to not treat at all”.  There is a lot to consider when deciding whether or not to treat a plant chemically, but that topic is beyond the scope of this article.

What is the issue with neonicotinoid use and bees?  The reason neonicotinoids are great options for pest control are ease of application, larger windows of application timing, and more targeted applications.  Using topical sprays to control pests requires very specific timing (pest usually needs to be present at the time of spray), and there is a risk that other non-target plants may get sprayed (wind drift).  Also, non-targeted insects present at the time of application can come into contact with the chemical.

A systemic application is much simpler: no spraying may be required (usually applied as liquid drenches into the soil around the root zone of the target plant, or injected directly into the tree), only insects feeding on plant tissue are targeted, and timing is much less critical since the chemical resides within the tree, eventually breaking down so reapplication is necessary for continued control.  And this is the question raised by many concerned people: If the plant tissue has enough chemical to kill insects feeding on the plant, isn’t it possible that the nectar produced by the plant’s flowers will be laced with the chemical as well?  So how does this affect bees?  These are very reasonable questions, and I agree that they merit consideration.

I was intrigued to see Bernadette Mach (Department of Entomology, University of Kentucky) on the speaker schedule at the Ohio Chapter ISA Tree Care Conference in Columbus, Ohio, this year.  Intrigued, because she was speaking on the topic of neonicotinoid levels that persist within a plant after treatment, specifically in nectar.  Her talk was in two parts, both of which applied to our concerns as commercial applicators.  The first half dealt with her studies on which flowering plants were attractive to bees.  The second half was measuring residual levels of systemic chemicals in nectar following application at label rates during different times of the year.  Details of her study informing the second half of her talk can be found online (Uptake and Dissipation of Neonicotinoid Residues in Nectar and Foliage of Systemically Treated Woody Landscape Plants). 

In short, there were several important details that I came away with:

1. Of two chemicals commonly used, one has a lower residual in nectar than the other.
2. The timing of the application matters.  Applications made post-bloom had a low residual in nectar the following year.
3. For some plants, the issue does not matter.  For example, Boxwood, in particular, has caused me difficulty.  Leafminer is a very common insect pest that can destroy Boxwoods, but it can be readily treated with a systemic application.  Last season I began communicating with clients my concern over treating Boxwoods and potential harm to bees.  After communicating with Bernadette specifically on this topic, I feel more comfortable continuing with Boxwood treatments as usual.  The reason is that Boxwoods are not a plant that attracts bees, so there is a greatly reduced risk that they would feed on the nectar.

As a Certified Arborist and licensed commercial applicator making recommendations to clients, I need to consider each plant prior to treatment.  Yes, the client wants to control Magnolia Scale, but should we attempt to do so systemically?  Is this plant attractive to bees?  If so, should we time the application post bloom?  Will this concur with the insect life stage being targeted?  What about other options?  Can we apply a targeted topical spray that will be effective?

In some cases, nothing more will be possible than to explain to the client the implications of treatment.  For example, if the client has a Hawthorn that consistently looks ugly each season when the leaves turn brown and blotchy due to Hawthorn leafminer, I can explain that the best way to control this pest is with a systemic application in the fall (which is essentially pre-bloom) to protect the tree from the pest in spring.  This means that there will be higher levels of neonicotinoid in the nectar the following spring, and since bees are attracted to Hawthorn blooms there is a chance they may be affected by the chemical.  Leafminer in Hawthorn causes damage that is mostly aesthetic.  Once the client considers all this, she may simply choose to leave the tree untreated and deal with some less than perfect leaves. 

Ultimately Certified Arborists that are licensed commercial applicators will be making applications based on label recommendations provided by the specific chemical manufacturer.  However, we need to follow the thought process outlined above to make responsible decisions, understanding that our choice of which chemical to use when to apply it, and how to apply it may have effects that reach further than simply trying to save one plant, or make it look better.

José Fernández
ISA BOARD CERTIFIED MASTER ARBORIST® OH-5129B
ODA COMM. PESTICIDE LIC. #105859 (Categories 2B, 4A, 6A, Core)
TREE RISK ASSESSMENT QUALIFICATION (TRAQ)

Did You Know Construction Can Kill Trees?

We see it all the time: trees surrounding a newly built home dying as a result of soil compaction and mechanical damage from heavy machinery, as well as change in the native grade affecting soil depth and water flow. A tree preservation plan is needed prior to construction which prioritizes your woody landscape as an important part of your construction project. With a Pre-Construction Tree Preservation Consultation from Arbor Answers, our experts will build a custom plan for your construction site to encourage the trees to thrive following the completion of the project. 

Options for the Pre-Construction Tree Preservation Consultation:

• On-site meeting to discuss construction plan and desired trees on the property

• Customized plan to help protect your trees during and after construction

• Installation of temporary fencing to give trees proper perimeters (if needed)

• Installation of temporary root zone protection (if needed)

Contact us before you build to maintain the beautiful wooded landscape you desire!