Emerald Ash Borer and

Milwaukee's Initiative

By Dylan Robert Weigel

Contents

Introduction .................................................................................................................................3

Life Cycle ....................................................................................................................................3

A Brief History of EAB .................................................................................................................4

Milwaukee's Plan ........................................................................................................................5

The Urban Forestry Internship ....................................................................................................7

Duties ......................................................................................................................................8

Consequences of letting the Invasive Flourish ..........................................................................11

Quantitative Losses ...............................................................................................................12

Qualitative Losses .................................................................................................................14

The System Set in Motion .........................................................................................................15

Our Current Status ....................................................................................................................16

Introduction

Emerald Ash Borer is an invasive beetle from Asia that kills Ash trees in its larval

phase. The Beetle was found in America in 2002 in Detroit, and has since then, been

sweeping across the United States. Anticipating this, Milwaukee founded a program

that uses college students to inject trees in order to stop the spread of this beetle.

Given the chance, this beetle could be detrimental to Milwaukee's commerce and

image.

Life Cycle

Emerald Ash Borer takes one or two years to complete its life-cycle depending

on; the timing of egg deposition, the health

and stress level of the tree, and local

temperatures(Gould et al. 2013). After they

emerge, Adult borers fly into the canopy and

feed on leaves for most of their lives(Gould et

al. 2013). After one week, they begin mating

and the females lay eggs 2-3 weeks after on

the trunks of trees(Gould et al. 2013). About two weeks after this, the larvae bore

through the bark to the phloem and out of the sapwood where they feed until the

weather cools down in the fall(Gould et al. 2013). As Winter approaches, the mature

larvae excavate pupal chambers in the sapwood and fold into an overwintering J-shape.

After development in the winter, they chew through the bark as adults and can fly out

immediately after. The damage to the tree comes in the larvae stage as the tunnels

they bore disrupt nutrient uptake, killing the tree from the top down.

A Brief History of EAB

Emerald Ash Borer, Agrilus planipennis, is an invasive species that was

discovered in the United States in 2002, in Detroit, Michigan, and Windsor, Ontario, also

in the summer of 2002. Since this initial infestation, clusters have been found every

year since then in; Ohio, Indiana, Illinois, Maryland, Pennsylvania, West Virginia,

Wisconsin, Missouri, Virginia, Minnesota, New

York, Kentucky, Iowa, Tennessee, Connecticut,

Kansas, Massachusetts, New Hampshire, North

Carolina, Georgia, and Colorado(Krause 2009).

There is no conclusive evidence to support their

method of arrival, but the most popular theories

are that they were transported in wood packing

material within a cargo ship, or airplanes coming from Asia, from which it

originates(Krause 2009). To date, EAB has cost these states hundreds of millions of

dollars, forced the implementation of stricter tree removal regulations, and cost

industries that utilize these trees tens of millions of dollars(Krause 2009). In order to

combat this invasive species, various methods of removal have been initiated in all of

these states such as removal of infected trees and introducing natural predators,

Wisconsin however, tried something different. In 2007 and 2008, Milwaukee's Forestry

Department studied different types of trunk injection in order find out which combination

of chemical and delivery system worked the best(Krause 2009).

Milwaukee's Plan

The City's preemptive approach on containing and eliminating the beetle came

as a reward to keeping a watchful eye on the destruction being wrought on the Midwest.

Seeing the trends unfold, the city began to create a management plan that was

threefold; Risk Assessment, Educating the public, and Risk Management.

The biggest challenge of risk assessment was to put into numbers, how

widespread , and to what extent of a problem scaled to. One method that was used

was a computerized spatial street tree inventory, or i-Tree Eco, and a hyper spectral

imaging-derived ash classification(Krause 2009). I-Tree Eco is a software application

designed to use field data from complete inventories or randomly located plots

throughout a community along with local hourly air pollution and meteorological data to

quantify urban forest structure, environmental effects, and value to communities.

Baseline data can be used for making effective resource management decisions,

develop policy and set priorities(Krause 2009). After these steps, it was apparent that

Milwaukee would be taking a huge risk to not acknowledge this threat.

The next step included educating elected officials in order to raise awareness

and gather support. Up until this point, Emerald Ash Borer was not thought of as a

threat to our City and State, bolstered by the fact that we had the dense concrete jungle

of Chicago to block its spread. These myths were obviously debunked after further

investigation, and the possible scope of this problem and its costs were made apparent

to city officials. The next obvious question revolved around the risk to the public, would

the treatment of these trees be detrimental to Milwaukee's citizens? After studying

different types of delivery systems, one method seemed to work the best, but was not

cost effective in terms of volume of pesticide, so for the time being, the program was

dead.

It wasn't until late 2008 that a new chemical, emamectin benzoate, or its more

common name; TREE-äge, was developed and showed promise for the project. What

was unique about TREE-äge was that it was able to provide protection for 2-3 years,

whereas other products required an annually application(Krause 2009). TREE-äge's

mode of action is a Chloride Channel Activator that prevents the insect muscle from

contracting(Krause 2009). This paralyzes the insect which stops it from feeding within

hours of ingestion, which compared to the 3-4 years it takes to kill the tree, this is the

blink of an eye(Krause 2009). At this point in time, there was only one company that

sold the restricted-use pesticide, Arborjet, so provisions were made and a budget got

put in place to buy all necessary equipment and chemical. By May of 2009,

preparations were complete and the project was able to commence.

The Urban Forestry Internship

Beginning in May of 2009, a total of 30 city employees were trained in order to

offer a large enough pool of trained injectors. The two main requirements of this

internship was the possession of a valid Wisconsin Driver's license, and a Pesticide

Applicator License (class 3.00-Turf and Landscape). The three lesser requirements;

basic tree identification, familiarity with a GIS map, and a basis in customer service

were used to separate applicants, which were mainly college students. The reason for

this was that it was a special project in that was only a seasonal position, and college

students for the most part, have younger backs. Once an ideal amount of applicants

was reached and then briefed, groups were formed and then given quarter sections of

the city to inject.

Groups were usually three or four in order to allow the rotation of duties because

some were more physically intensive than others. After arriving to the destination,

hydraulic guns were filled and calibrated with chemical, being careful not to waste what

was worth its weight in gold. This step of calibration was exceedingly important for a

few reasons. If the guns start injecting more pesticide than the tree can take up, the

pressure will force the bark to separate from the cambium, which will inevitably rupture

the bark, opening the tree up to infections. This may also cause the chemical to seep

out of the tree, wasting money and putting children and pets at risk due to accidental

ingestion. Though if the chemical going into the tree is lower than the desired amount,

then the treatment would be ineffective and could put the whole block or quarter section

at risk of being infected. Though this was kept in check by doing periodical calibrations

throughout the day and a chemical log of the expected versus actual volume of

chemical used.

Duties

The actual internship can be divided into five duties; DBH (Diameter Breast

Height) measuring, drilling, plug fitting, injecting, and sign posting.

Measuring the DBH is a crucial step

in this process because it determines the

amount of chemical being put into the tree

by determining the quantity of holes

needed. A measuring tape is wrapped

around the tree at breast height and then

its DBH is referenced against a dosage

chart for the number of holes to be drilled.

Once the trees have been

marked with the appropriate number of

holes, the person designated to drill,

drills 3/8 of an inch holes around the

base of the tree. It is important

however, that these e holes be spaced

out as uniformly as possible in order to allow an even concentration of pesticide to each

side of the tree.

The plug setting is one of the safety

mechanisms in these applications. The

person setting the plugs puts one plug into

each hole and then sets them by pounding

them in with a hammer. An efficient plug set

will be deep enough to stop seepage from

pressure within the tree, but not so deep that

the tree will not be able to exude the plastic plug. The plug is tapered at one end and

has a "user friendly" hole at the other allowing it to be set tight and aid the person

injecting.

Injecting is often the least

desired job as it is the most strenuous

and most dangerous. This job requires

the user to where a "backpack" for the

lack of a better word, which at

maximum capacity holds 1000psi in an

aluminum tank and about two liters of

chemical. The job itself is fairly easy in

that one just has to keep an eye on the pressure gauge and avoid seepage. One

hazard of this job however, is when the plug is not set deep enough, and the internal

pressure shoots pesticide back at the user. This is when knowledge of a restricted-use

pesticide comes in handy because there are specific ingestion, inhalation, and skin

absorption rates that apply for different chemicals.

The last duty, usually done by the person doing the measuring, is the posting of

pesticide application signs. Signs function to inform the community of the application,

and to alert other city employees of which quarter sections have been done. In regards

to the public, the signs show a word of warning in order to keep children and pets off of

the tree in case of seepage. They also inform the public of existence of Emerald Ash

Borer, and who they can call in order to learn more information about it.

Besides the primary objectives listed above, there is also a passive appearance

we strive for when representing the city. In one part, we need to represent the city as a

wise use of tax dollars and not give off the typical impression of a lazy city worker.

Keeping this image up reinforces faith in the government the services that it provides to

its taxpayers. We also need to play the role of informant, and alert citizens to what we

are doing, and why we are doing it. A typical conversation with a citizen would go as

such:

Citizen: Hey, what are you doing? Are you cutting down my tree?

Intern: Oh hello there, no we're not cutting your tree down, we are injecting them

for Emerald Ash Borer.

Citizen: What is that, one of those bugs?

Intern: Yes, it invades ash trees like the one you have in front of your house here.

Citizen: So my tree's infected?

Intern: No not at all, this pesticide is sort of like a vaccine that protects the tree if

the insect tries to infect it.

Citizen: Oh good, so how do I know if my tree is infected?

Intern: The tree will begin to look dead near the top and will have holes that have

the about the same diameter as a dime.

Citizen: If I think my tree is infected, who should I call?

Intern: There's a number on the pesticide signs that we're putting up, otherwise I

can give it to you now.

Citizen: Alright, thank you, try and stay out of the sun!

Though many of the conversations can go a lot more hostile than that with people

wanting us to chop down their tree or complaining about how the city hasn't fixed the

pothole in front of their house. In any case, most residents, whether it be in a lower-

class or upper-class quarter section, don't know about Emerald Ash Borer and its

effects on the ecosystem and neighborhood.

Consequences of letting the Invasive Flourish

With any invasive species, there will always be negative effects on the

environment due to the fact that it can either outcompete local organisms, or reproduce

faster than local populations. This can be detrimental to the system by either using up a

viable resource, or influencing the population trend towards a monoculture. In either

instance, if left unchecked, can have costly negative effects on the ecosystem.

Quantitative Losses

Ash trees make up around 20% of the total tree population in Milwaukee, not

including trees located in parks(EAB Statistic). Not treating for this insect would

inevitably lead to the loss of all of those trees, an average of one in five trees missing

per block. That is not a correct assumption though because there are many instances

where the whole block, both sides are Ash trees, which would mean a 100% reduction

in all of the things the urban canopy provides.

The loss of shade has a couple different effects on the surrounding communities.

Shade obviously provides a refuge to individual people and animals in the later days of

summer, but provides much greater services to the community as a whole such as

lowering the ambient temperature. Research done by Cambridge University found that

the urban forest "moderates the urban heat island effect, generally reducing the ambient

temperature as much as 6-8 degrees F during the summer, which in turn reduces the

amount of energy need to run air conditioners"(EAB Statistic). When extrapolated to

Milwaukee, there is a savings on summer cooling of $138,000 annually(EAB Statistic).

A loss of shade is always the most obvious problem because it is the one that

people immediately notice, but losing a canopy that big has more far reaching problems.

Not many people realize how much air pollution mitigation trees actually do for us. The

DNR has done extensive research and found that city trees actually perform a lot of

services for us such as trapping particle pollutants such as pollen and dust that can

damage our lungs, especially asthmatics(Trees Reduce Air Pollution). They produce

enough oxygen on each acre for 18 people every day(Trees Reduce Air Pollution).

They absorb enough CO2 on each acre, over a year's time, to equal the amount of CO2

produced by a car travelling for 26,000 miles(Trees Reduce Air Pollution). This

happens when the trees absorb pollutants through the pores in the leaves, and then

trapped and filtered(Trees Reduce Air Pollution). They are then washed to the ground

where they are absorbed by the soil and broken down by microorganisms such as

bacteria. If this canopy was lost, the city would lose $240,000 in air pollution mitigation,

meaning that if the city wanted to keep the current level of air pollution after losing 20%

of the canopy, it would have to invest $240,000 in order to do so(EAB Statistic).

Another service that this urban canopy provides for the city is the reduction of

stormwater into our sewers. Stormwater management has always been a high priority

in Milwaukee, evidenced by the $1 billion investment in the Deep Tunnel project. Also,

with restrictions from the State and MMSD in regards to stormwater regulation,

provisions would have to be made in order to deal with essentially adding all the water

that was usually regulated by the street trees, into the already overloaded system. To

quantify this, a 20% reduction in our urban canopy would be a loss of $2.6 million in

storm water regulation benefits(EAB Statistic).

Qualitative Losses

While these services are important, they only take into consideration the

quantifiable, and not the qualifiable losses such as habitat loss. Not so much habitat

loss per tree, but habitat loss due to defragmentation of the whole metapopulation.

Ecosystems that sprawl the area of an urban

canvas are often patchy as large areas are

seldom found. This means that the

interconnectivity is especially important and

removing one tree or "corridor" may displace not

only the species utilizing that tree, but all those

who use it for transportation and periodical feeding. The effects are almost impossible

to accurately quantify because we can't know every species living within one of these

trees and how exactly they benefit from it.

Another qualitative loss could be in the City's

aesthetic image, because beauty is in the eye of

the beholder, but then again, not many people are

moving to Detroit nowadays. Stemming from

personal experience, it is just awe-inspiring to drive

down a street and have the entire street shaded with small inlets of sun, engineered by

an archway of branches. It is especially challenging when we are trying to change the

city's image from a "conservative, frugal factory town to vibrant, livable and

cosmopolitan city", when we are in the middle of the "Go Green" era and we are losing

20% of our poster child(Chicago Tribune). Though these losses seem tame when

compared individually, they can be a collaborative loop of amplifying variables when set

in motion.

The System Set in Motion

To say that that these consequences happen in somewhat a linear fashion is a

misnomer, because the same driver can come back and influence the system later on in

the cycle. The immediate loss to the city is in tax dollars, about $750 to remove and

replace each ash tree(EAB Statistic). Seeing as there are 36,000 ash trees on the City

streets, the total escalates to $27 million(EAB Statistic). Milwaukee's Forestry District

Budget for 2014 is $6,899,910, conservatively, if it takes 10 years to remove all of the

trees, that's still an extra $2.7million per year(City of Milwaukee Budgets). The problem

is, that there is no negotiation here, infected trees must be taken down due to safety

hazards, which means that either taxes will have to get raised, or the money will have to

be taken from elsewhere. Taxes are already on the rise and will continue to do so, the

most likely cut would be from within the Forestry Department under Nursery Operations.

What this would mean, would be a decline in aesthetics, such as degradation of flower

beds, and because of the increased work load for the Arborists, less tress being pruned.

Once this removal is over and all the new trees are planted, it's still not over. A

decline in aesthetics leads to a decline in property values, evidenced by such

neighborhoods as 76th and Good Hope Rd. Lower property values bring in less

desirable inhabitants, and in turn bring in less desirable, cheaper businesses, and with

this turnover in middle to lower class inhabitants, comes more abuse to the canopy.

Going through neighborhoods in almost every section of our City, and finding trees;

Ash, Oak, Maple, etc. spray painted with gang signs or birthday messages, or bark

completely stripped off for reasons unknown to myself, exposing these trees to a new

invasive, repeating the entire cycle over theoretically, leading to more decline, and more

tax dollars.

Our Current Status

Currently, the program is budgeted to have about $1 million each year, allowing

the City to treat for 20 years before even getting close to the $27 million mark(EAB

Statistic). During this time, the oldest and most infected Ash are removed and a new

species is planted in its place. Staggering the growth of these trees allows

neighborhoods to not completely lose their urban canopy and any of its benefits. As the

program moves along, more and more constituents are made increasingly aware of the

problem on the horizon, and may help us get a handle on this before Milwaukee falls

into the same fate as cities such as Detroit.

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