Tree Care Advisor Newsletter

Inside This Issue:

Need a “small” Tree? By Dave Hanson

1

Quick Hits / Volunteer Opps By Dave Hanson

2

Putting Down Roots: By Cliff Johnson

3

Please Welcome,

TCA Class of 2004

5

Tree Friendly Fungi By Linda Guertler

6

Why? Pruning Trees By Dave Hanson

11

Emerald Ash Borer (EAB) News from Sue Burks, MnDNR

17

Contacts

24

Arbor Day, Involvement By Betsy Mcdonough

10

Volume 11 Number 2 Dave Hanson and Gary Johnson, Managing Editors

http://

www.mntca.org

Spring has Sprung!

I’ll get you started on page 5. Check out “who” arrived in the TCA program and

look at where they are taking the TCA message…

Linda Guertler - one of the spring arrivals to the TCA program provides a pretty

good look at the benefits of fungi on page 6…

Spring also brings a moment of reprieve to our trees - at least it should. During

the spring months, give the trees a break. Put your time and energy into pruning

the grass and quit pruning the trees for a little while. Give them a rest while they

leaf out… See the article on page 11 regarding the “whys” of tree pruning or at

least some of them...

Are you still with me? Now you can go back and read the other articles that have

been included in this newsletter… Those exotics are still with us from a good old

standby called buckthorn to a new and potentially lethal (to ash species) bug called

the Emerald ash borer…

And remember - it’s Oak Wilt Season...

Need a “small” Tree?

The family Rosaceae covers a number of Minnesota’s native trees and shrubs.

Members of the family include the cherries, apples, hawthorns and the juneberries,

to name a few. However, it is one of the other family members that is the focus

of this article.

The American “Rowan” tree, like many of us, finds solitude in the cool northern

forests of North America. One of the regions where it grows best is in the

northern great lakes region. This small stature tree, especially its cousins, has be-

come popular as an ornamental in the northern states due to its finely toothed

compound leaves, flower clusters and sometimes persistent fruit.

Continued on Page 19

Page 2 Quick Hits

A “Contact Tree”

The TCAAG has added several new members and is currently considering a new name.

TCAAG just doesn’t flow and roll off of one’s tongue… So, if you have an idea for a new acronym

or a project for the TCAAG to work on - let us know. We will be getting together again on Thurs-

day, July 29th at 6:00 pm. Or bring your ideas to the meeting in Green Hall room 116A on the

Saint Paul Campus.

WWW.MNTCA.ORG

Gearing up for the new season! There are some volunteer opportunities listed on the website.

There is also a good deal of valuable information under “Resources and References.” I have been

slowly expanding the “TCA Tree Identification” pages and “Notes From the Field.”

Remember this website is for TCAs ! Let me know what you would like out there!

Again, there are opportunities to help out with various activities on campus

with the TRE nursery. Typically these opportunities are research related -

but can be rather messy and the work is far from glamorous.

It is my understanding that there was good response to the request for a “Phone Tree”

and there are a good number of contacts out there. As I updated the directory for 2004, I

flagged the “Contact” TCAs with an asterisk (*) behind their names.

As of yet, this method of contacting people has not been used, but if you need to reach the

people in your area for a planting event or speaking engagement that needs an audience or

a speaker for that matter - let’s give it a whirl.

The planting season is upon us!

Help some kids plant a tree!

It can be fun and rewarding!

Photo: Dave Hanson

Page 3 Putting Down Roots - A column in the Chaska Herald.

By Cliff Johnson, Carver/

Scott Master Gardener

Glossy green leaves in late

fall spell trouble

Everyone loves to

look at colorful fall leaves.

In a few months, we’ll

marvel at the reds, yel-

lows, oranges and scarlets.

This fall, train your

eyes to search for green

leaves on small trees after

all the red, yellow, orange

and scarlet leaves have

cascaded from the tree

branches. The green

leaves you see still clinging

to branches in late Octo-

ber and early November

after all the colorful leaves

have fallen are buckthorn.

A weeks ago, I

spent a half day removing

and digging out the roots

from a very handsome

nine-year-old fernleaf

buckthorn (Rhamnus as-

plenifolia) that was planted

right outside my office

window in 1993 by a land-

scape contractor. It had

grown to about 15 feet

and, as the name implies,

sported very attractive

fern-like leaves. It also

produced -- for the first

time this summer -- small

black berries.

I liked the tree a

lot until I discovered the

berries. When eaten by

birds, these berries are

spread across my yard and

the surrounding neighbor-

hood and the seeds sprout

into seedlings that will not

become attractive fernleaf

buckthorns. Rather, the

seedlings revert to the

non-native, invasive parent

buckthorn species.

Removing my at-

tractive ornamental buck-

thorn was a lot of work

but the tree had to go. I

can’t very well go on writ-

ing with a clear conscience

about buckthorn eradica-

tion when I have a source

of the problem growing in

my yard. My tree was

okay as long as it didn’t

produce berries but, given

the plant’s propensity to

propagate from seed, it

was time to reach for the

saw and shovel.

Later in the same

week, I made a house call

at a home on Lake Waco-

nia where a beautiful land-

scape had been established

20 years earlier. Some of

the trees and shrubs at

this site, unfortunately,

have become overgrown

and unsightly. I was in-

vited to the site to offer

advice on pruning and gen-

eral tree and shrub main-

tenance. A dozen of the

woody plants in this land-

scape are buckthorns -- a

popular landscape plant

two decades ago. Native

to Europe, buckthorn was

imported to North Amer-

ica in the late 1700s and

widely planted as hedging

material until 1930. Orna-

mental varieties of buck-

thorn (like my fernleaf va-

riety) continued to be sold

and planted right up until

the last few years. The

buckthorns on this Waco-

nia lot were full of beauti-

ful 1/4-inch diameter ber-

ries. And, you guessed it,

tiny buckthorn seedlings

are popping up every-

where.

I’ve written about

buckthorn before, and

perhaps you wish I’d find a

new topic, but buckthorn

is a serious problem in

Minnesota yards and

Rhamnus cathartica - terminal

thorn and “hoof” like buds of a

buck - hence the common name

buckthorn.

Photo: Dave Hanson

Mature leaves in August. Note

the veination pattern refered to

as arcuate veination - arcing

from the leaf base to the apex.

Photo: Dave Hanson

Page 4 Putting Down Roots...

wooded areas and each of

us can play a part in pre-

venting a total takeover by

this invasive plant.

You may have

heard the term allelopathy.

It refers to suppressive

effect of one plant on an-

other through production

and release of natural

compounds. Black walnuts

possess allelopathy. To-

matoes and peppers and

some other plants will not

grow in soil where black

walnut roots are present.

Sunflower seeds also cause

this phenomenon. There

are no plants growing un-

der my bird feeders.

Buckthorn puts all

the pieces together for

total takeover: A vigorous

root system, mycorrhizal

root fungi, a long growing

season, hungry birds that

spread the seeds, no natu-

ral predators and an allelo-

pathic effect on other

plants.

The first step in

controlling the spread of

buckthorn is identification.

That’s why I hope you’ll

stop and take a close look

at the glossy, green-leafed

plant this fall after the

other leaves have fallen.

Mary Lerman, hor-

ticulturist with the Min-

neapolis Park and Recrea-

tion Board, says the

woodlands and wetlands in

Minneapolis are infested

with common buckthorn.

“One only needs to drive

along Minnehaha Parkway,

the River Road parkways,

through Theodore Wirth

Park and along Diamond

Lake to see its devasta-

tion,” she says. Some ex-

perts have written that, if

buckthorn isn’t removed

soon, future generations

will not have the opportu-

nity to enjoy the flora and

fauna of woodlands and

wetlands.

Buckthorn eradica-

tion is complicated and

labor intensive. If you

have buckthorn present

on your property, I en-

courage you to begin the

process of eliminating it.

The Minnesota Depart-

ment of Agriculture and

the University of Minne-

sota Extension Service

have published helpful

guidelines for fighting this

invasive plant. Eradication

procedures and close-up

photos of the leaves and

berries can be viewed on

dozens of internet sites.

In some areas,

homeowners and other

volunteers have joined

forces to eradicate buck-

thorn from entire

neighborhoods. Perhaps

you are just the person to

begin a buckthorn removal

campaign in your

neighborhood.

Okay, I’ve said my

piece. By the way, my

buckthorn removal project

had a happy ending. I

drove to a local garden

center and bought a small

but very attractive blue-

needle Japanese white pine

and planted it where the

fernleaf buckthorn grew

for nine years. I should

have planted the pine in

the first place.

New emerging leaves - April 29

Photo: Dave Hanson

Late September leaves and ber-

ries

Photo: Dave Hanson

Page 5 Please Welcome

“The TCA class of 2004.” At the beginning of February, I was a little concerned

that we would have to cancel this years TCA core course due to lack of partici-

pants… Well with a little flexibility on our part and some last minute calls and re-

quests to the regional offices – we filled to capacity and added a few extras. Yes,

extras; two urban forestry students from the University of Minnesota and a Re-

gional Extension Educator from south-central Minnesota (my old stomping

grounds).

As you can see members of this class have come from all four corners of Minne-

sota and they are truly taking the TCA message farther than it has gone before. To

me this is really exciting – it doesn’t matter what size the community is in Minne-

sota – there needs to be a voice for the trees and TCAs are it! Thanks for getting

out there and speaking on behalf of the trees… Dave Hanson

Saint Paul Course

Instructors:

Gary Johnson Dave Hanson

Charles Krueger Diane Richards

Gary Wyatt Thomas Dunlap

Nori James Diane Booth Daniel Baltes

Kathleen Bonnett Janet Erdman

Linda Guertler Keith Dougherty Rebecca Bandelin

Ada Hegion Beth Storey

Barbara Whipple Michael Oslund Shannon Lloyd

Norman Erickson Mary Laine Jan Morlock Louise Levy

Cynthia Hammel Holly Johnson

Ron Pierce Winnie Williams

County Anoka

Blue Earth Blue Earth

Carver Carver Cook

Dakota Dakota Dakota Dakota Douglas

Dunn, WI Hennepin Hennepin Hennepin

Isanti Nicollet Olmsted Ramsey Ramsey St. Louis

Washington Washington Washington Washington

Judy Harder Steve Harder

John Jirak Dorinda Speh Patricia White Marcy Bode

Charles Nordby Laurie Iverson

Mark Rose Kristi Megli

Robert Welker

County

Cottonwood Cottonwood

Le Sueur Murray Murray

Nicollet (Brown) Redwood Redwood Redwood

Sibley Yellow Medicine

Lamberton Course

Instructor: Gary Wyatt

Regional Extension Educator

Mankato Regional Center

Photo of the Lamberton

crew...

From Cook County in the

Northeast to Yellow Medicine

on the west edge - The TCA

program is getting around.

Page 6 Tree Friendly Fungi and Bacteria

Linda Guertler Dakota County TCA, University of Minnesota, MS of Ag in Horticulture

Graduate Student

Not All Fungi and Bacteria are Bad! For many people, the news that their prized tree is loaded with thousands of fungi and bac-teria would likely be distressing. You might be surprised to learn that most microorgan-isms growing on or near trees, such as fungi or bacteria, are not harmful to the tree and may in fact be quite beneficial. The relationship is similar to that of the human body, which constantly harbors thousands of fungi and bacteria. Some even improve the functioning of certain activities, such as the bacteria that live within the intestinal tract where they aid in digestion and produce Vitamin K. In addition, for both trees and the human body, health can be more easily maintained when colonized by the “good guys” because it makes it harder for the “bad guys” to get established and cause disease. When the environment is changed so that optimum growing conditions are altered, this balance may be disrupted. Trees (like people) under stress have less disease resistance and may become vulnerable to harmful fungi or bacteria.

The Bad Guys With all the publicity given to the disease causing fungi and bacteria, it is no wonder people are unaware of the good things these microorganisms can do. Just say the words “Dutch elm disease” and “Oak wilt” and a look of sadness or worry is likely to be the response.

Common Fungal Diseases • Dutch elm disease has had a devastating impact on the American elm throughout

the northeastern United States. It is a fungal disease that is spread overland by beetles that pick up fungal spores when they feed on the sap of infected trees and then move on to infect healthy trees. It also spreads below ground through roots that intermingle with the roots of neighboring elm trees. When the tree detects the presence of the fungus infection, it attempts to prevent its spread by clogging up the water conducting vessels. Unfortunately, this process also deprives the tree of water. Leaves quickly begin to wilt, then turn yellow and brown, and eventually branches and the entire tree dies as the disease continues to spread.

• Oak Wilt is another fungal disease that is wiping out great numbers of oaks in the

eastern part of the United States, especially the Upper Midwest, including central Min-nesota. The fungus that is responsible for oak wilt is different than the one that causes Dutch elm disease, but it is spread in a similar manner. The predominant means of transmission is through root systems that graft with each other, but it can also be spread overland by sap beetles. The beetles are attracted to the spore bearing mats produced on trees that have been killed by oak wilt and they then fly on to feed on the sap from fresh wounds of healthy oaks and contaminate them with the spores stuck to their bodies. As in Dutch elm disease, the infection process triggers a response in the tree that causes the vascular system to plug up and stop the flow of water. Leaves rap-idly wilt, turn color and die around the outer margins and from the top of the tree

Below: The Beetles of DED and

an Elm showing early “flagging.”

Below: An Oak killed by oak wilt

and some of the beetles respon-

sible for overland transmission.

Page 7 Tree Friendly Fungi and Bacteria

crown downward. The red oak group is more susceptible than the white, but either can get oak wilt. Red oaks can be killed within three weeks after infection, while white oaks can take several years to die.

Common Bacterial Diseases • Fire blight is a bacterial disease of plants in the rose family, including apple, crabapple

and mountain ash. Infections are typically spread from tree to tree by bees feeding on flowers. Very rapid death of tissue results, causing branches or the entire tree to look like it has been scorched by fire within a short time frame. Infections result in the de-velopment of cankers and death of branches or the entire tree.

• Crown gall is a disease caused by a bacterium that lives in the soil and when it infects

a tree it causes the tree to form tumor-like galls on the roots and stem. Although the galls can become quite large and grotesque, they typically only cause stunting, make the tree more susceptible to drought damage, winter injury and infections from other or-ganisms. Unless the gall completely girdles the stem a tree is rarely killed.

What Do The Good Ones Do? • Mycorrhizae are the home run hitters in the world of beneficial tree fungus associa-

tions. Mycorrhizae, meaning “fungus-root,” are formed when one of the many differ-ent fungi that grow naturally and abundantly in native soils hook up with tree feeder roots in a mutually beneficial way. The fungus spreads out by tiny growth filaments called hyphae that penetrate either between or into the cells of the tree roots. This joint association is called mycorrhizae. The fungus benefits from the relationship by getting carbohydrates (energy) from the tree. The fungus decomposes organic matter, causing nutrients to be released. The tree benefits from the mycorrhizae by the fun-gus being able to grow more widely and deeper into the soil than the tree roots can, increasing the trees access to moisture and nutrients, including phosphorous, nitrogen, and copper. Some protection from disease invasions also occurs because of the pro-tective covering the fungus provides over the tree root. Trees that don’t have my-corrhizae can survive, but most healthy plants have them and typically perform better when they do, especially if they are growing in poor soils. They usually have larger roots, grow more quickly, and are more tolerant of stress.

• Soil fungi and bacteria associated with trees:

Improve soil fertility by digesting and releasing nutrients from organic mat-ter (nutrient cycling);

Improve soil tilth by causing soil particles to stick together in aggregates;

Control many harmful microorganisms by attacking them directly or preventing their establishment in the tree because the good guys were their first, and;

Release nitrogen from organic matter or directly from the atmosphere into a form that can be used by trees.

Hyphae (small projections into

the soil) of Mycorrhizae on root

tips greatly increase the absorp-

tion area of the root tip.

Myco means fungus

Rhiza refers to roots.

Bees and Fireblight

Crown Gall...

Page 8 Tree Friendly Fungi and Bacteria

• Fungi and bacteria on leaves, flowers and other plant parts benefit the tree by

fighting off disease causing organisms. If a tree has numerous types of harmless bacteria or fungi that have taken up residence, when a harmful new type tries to move in it has a more difficult time getting established.

How to Keep the Good Guys Around To keep beneficial fungi and bacteria thriving and in tip top shape, it is particularly important to maintain the health of the soil where the tree is growing. Healthy soil will be best main-tained if you or anyone you contract with to do work for you follows these rules:

Do’s

• Do maintain a layer of organic matter on the soil surface (e.g. wood chips, plant debris or compost). This is a source of food for soil microorganisms and nec-essary for their survival. It also helps avoid compacting soil and keeps the soil moist longer.

Don’ts • Don’t scrape off the surface layer of topsoil

• Don’t compact the soil. Soil compacted from activities like operating heavy equip-

ment or piling heavy objects over tree roots deprives tree roots and beneficial organisms of essential oxygen.

• Don’t mix up soil layers or dump large quantities of soil from another site.

• Don’t use soil fungicides or sterilizers.

• Don’t dispose of chemicals, petroleum or other toxic materials or construc-tion supplies on or bury in soil.

What if I did some of those bad things? Okay, so you don’t have the best soil and wonder if there is anything you can do to improve the situation and reintroduce friendly fungi and bacteria to the tree’s growing environment. Yes!

• Apply a surface mulch of organic matter. Fungi and bacteria thrive under different condi-

tions, so the type of material you apply will influence the balance of each that you have.

Bacteria will be more prevalent in fresh green materials, such as grass clippings, or moist (not wet) compost that has been turned frequently (turning breaks up the “webbing” fungi create when growing). To create a bacteria dominated compost, mix together:

25% high nitrogen material (manure or spring grass clippings)

45% green material ( any green plants, kitchen scraps or coffee grounds)

30% woody material (wood chips, sawdust, shredded newspaper)

Fungi will predominate in drier organic matter (less than 40% moisture) with less green material (or none, like wood chips) or compost that has not been turned very often.

• Spore inoculations of the fungal portion of mycorrhizae can be purchased for application

in soils, but under most circumstances they are not necessary. For a quick introduction

Page 9 Tree Friendly Fungi and Bacteria

of fungal spores when planting a new tree after digging the hole, mix in some native soil and compost to the soil before backfilling the hole. Fungal spores will likely be present in native soil, and compost will help create an environment they can survive in. Even if you don’t add native soil or purchase an inoculum of fungal spores, the spores of fungi that form mycorrhizae float ubiquitously in the air so they will become reestablished in time if soil conditions are right. So, add that compost!

• Whether applying wood chip mulch, compost, or any other organic matter, don’t ever

apply organic matter that smells bad or has an alcohol odor. Alcohol is produced when organic matter has not been well aerated and is toxic to plants in very small quantities. If you detect a bad smell, mix up the material frequently to introduce air and wait for the smell to go away before application.

A Final Word Keeping healthy populations of tree friendly fungi and bacteria is a good thing! Providing the conditions they need to be healthy and thriving, will help your trees remain healthy too.

For More Information Agrios, George N. 1997. Plant Pathology, 4th Edition. Academic Press. San Diego, CA.

Baker, Christine. 2002. Iowa State Extension Service – Extension News. Fungal Friends. Found at http://www.extension.iastate.edu/newsrel/2002/oct02/oct0208.html

Brady, Nyle C and Ray R. Weil. 2000. Elements of the Nature and Properties of Soils. Prentice Hall, Inc. Upper Saddle River, NJ.

Haugen, Linda. 1998. USDA Forest Service. How to Identify and Manage Dutch Elm Disease. http://na.fs.fed.us/spfo/pubs/howtos/ht_ded/ht_ded.htm

Hoitink, H., M. Drause and A. Stone. 2000. Disease Control Induced by Compost in Container Culture and Ground Beds. Ohio State University Extension Circular 177-01 found at http://ohioline.osu.edu/sc177/sc177_15.html

Ingham, Elaine. Brewing Compost Tea. Fine Gardening. Accessed 4-16-04 at http://www.taunton.com/finegardening/pages/g00030.asp

Jackson, Eric. 2004. When a fungus is a good thing. Science. Vol. 9 #24 found at http://www.thepanamanews.com/pn/v_09/issue_24/science_01.html

O’Brien, Joseph and Manfred E. Mielke, Dale Starkey, and Jennifer Juzwik.

USDA Forest Service. How to Identify, Prevent, and Control Oak Wilt. http://www.na.fs.fed.us/spfo/pubs/howtos/ht_oakwilt/toc.htm

Podila, Godi. 2000. MTU News. 4/24/00 found at http://www.admin.mtu.edu/urel/breaking/2000/genes.html

Rockwood, Larry. George Mason University. Mutualism course sheet found at http://mason.gmu.edu/~lrockwoo/Mutualismsp02.htm

Sinclair, Wayne A., Howard H. Lyon and Warren T. Johnson. 1987. Diseases of Trees and Shrubs. Cornell University Press. Ithaca, NY.

Shigo, Alex L. Some Tree Myths Corrected. Tree Trust for Haringay website accessed 1/04 found at http://www.treetrust.free-online.co.uk/MYTHS.HTM

University of Minnesota Extension Service. 2000. Bulletin BU-07403 Soil Manager. Website ac-

Page 10 Tree Friendly Fungi and Bacteria

cessed 4-16-04 http://www.extension.umn.edu/distribution/cropsystems/components/7403_01.html

Vaneste, J.L. 1996. Honey gees and epiphytic bacteria to control fire blight. Biocontrol News and In-formation. Vol 17. No. 467N-78N. found at http://pest.cabweb.org/PDF/BNI/Control/BNIRA28.PDF

Photos All photos except those otherwise noted - Keslick and Sons Technical Tree Biology Dictionary found at http://www.treedictionary.com/DICT2003/index.html

Crown gall photo – Wayne’s World. To Be or Not to Be a Gall. Website http://waynesword.palomar.edu/pljuly99.htm

Dutch elm disease photos - Haugen, Linda. 1998. USDA Forest Service. How to Iden-tify and Manage Dutch Elm Disease. http://na.fs.fed.us/spfo/pubs/howtos/ht_ded/ht_ded.htm

Oak Wilt photos - O’Brien, Joseph and Manfred E. Mielke, Dale Starkey, and Jennifer Juzwik. USDA Forest Service. How to Identify, Prevent, and Control Oak Wilt.

http://www.na.fs.fed.us/spfo/pubs/howtos/ht_oakwilt/toc.htm

In honor of Arbor Day, the City of Oakdale holds an annual tree giveaway for their residents.

Yesterday, April 24, TCAs Jane Kline, Diane Crea and Betsy McDonough along with our new

Washington County Master Gardener intern, Lynn Barnum, assisted in the giveaway. While

the city has done this for a number of years, this is the second year that a number of TCAs,

other than Jane (City's Tree Board member), have been involved. Last year we played a slightly

more passive role in that we were there to answer questions IF people had them. As we

watched a number of trees leaving with homeowners that clearly needed some pruning, we

saw an opportunity to get more actively involved and provide a greater service in the future.

So this year was a different story.

There were a total of 300 bareroot trees - Red Splendor Crabs and Northwood's Maples.

Due to our fabulous training and knowledge about proper planting depth and the conse-

quences of nurseries sometimes planting too deep, we decided we needed to inspect all trees

before they were planted AND give planting instructions to the homeowners. So, we formed

a line and as each homeowner received their tree they brought them to the TCAs, armed with

pruners and red markers. We saw some incredible root structures! As we were pruning

away the multitude of advantageous roots, figure 8's, and potential stem girdling roots, we had

the opportunity to talk with each homeowner and tell them how to correctly plant and care

for their tree. This was a great opportunity to get involved with the community, have direct one-on-one contact and educate a lot of people. People were very willing

to wait in line for their turn. They were curious, appreciative, and wanted to gain

the knowledge and understanding so they could care for their trees properly. All

in all - a great day. Thanks to Jane Kline for getting TCAs involved.

Respectfully submitted, Betsy McDonough

Arbor Day - Involvement Grows

Page 11 Why? Why do we prune trees?

By Dave Hanson

Many of us have had the pleasant (?) experience of the tag-along-toddler with only one question on their little mind, “Why?” While this repeated inquiry can be, shall we be po-lite and say, challenging! We understand that the tag-along-toddler is learning and catalog-ing some tidbits for later. Whether people are listening to a speaker or reading an article – the topic of pruning reduces many of us to the tag-along-toddler phase of our lives with one burning question “why?” This article will repeatedly ask that question and hopefully provide some answers besides, “because!”

Let’s get started with this comment: Trees in a “natural” forest are seldom pruned and they do fine. On the other hand people in urban areas insist on pruning trees frequently…

Why?

Are urbanites simply “control freaks” with a need to control some living thing? Not ex-actly, there are valid reasons (safety, health of the tree, and aesthetics) to get out there and take a good look at the structure and condition of the trees in our landscape. Trees in the natural forest for example tend to randomly drop limbs (natural pruning) and fall over unpredictably during storm events or from internal decay.

Increased potential for property damage and personal injury in the urban forest dictates that limb dropping and trees falling over should be predicted and controlled, as much as possible. Any tree may develop structural problems or become damaged in such a way that it presents a risk. So, developing a regular inspection and pruning cycle for landscape trees is highly recommended to help eliminate some of the “risk.”

Many consulting arborists are trained to identify those “risks” in trees and can make rec-ommendations to eliminate or reduce the risk to an acceptable level. Often reducing the risk can be accomplished without removing the tree by utilizing one of the following ap-proaches:

Three basic approaches to pruning:

From the United States Forest Service brochure “How To Prune Trees” (Bedker et al.):

1) Crown reduction:

A method to reduce the overall height of a tree.

Why?

Most often put into practice under power lines to alleviate line conflicts. According to a flyer from Connexus energy (Spring 2004) – “Trees are the number one cause of power outages.”

This approach may also be employed to clear site lines for a scenic over-look or vista.

Bad decisions leading to more

bad decisions: You cannot cor-

rect the decision to leave this

tree during construction by

pruning it excessively to raise

the crown and to “move” it

away from the building.

Photo: Dave Hanson

Power line clearance.

Photo by Chad Giblin, U of M.

Page 12 Why?

Crown reduction or drop-crotch pruning is not topping; yet, it should be consid-ered as a last resort treatment.

Why?

Crown reduction opens multiple large and small wounds on a tree and those wounds can be entry points for insects or disease…

2) Crown thinning / cleaning:

This technique is often used to open up the canopy for air movement through the tree and to provide light penetration to the understory. Beyond that, this pruning approach considers many things: correction of structural problems such as: tight branch angles, included bark, crossing branches, broken or split tree parts…

Why?

Correcting structural problems can prevent problems from loading events (wind, ice, or snow) or simply the weight of a maturing limb. Consider a limb or branch to be a lever arm that you learned about in physics – if you load that lever arm and it is not firmly attached to the tree or was previ-ously damaged it is likely to fail.

Crown cleaning also consists of removing deadwood, hangers (broken branches) as well as removal of diseased wood or insect infestations.

Why?

Deadwood and hangers (lodged, detached branches) present a risk to peo-ple, cars, houses and other objects (targets) below. Also, by removing signs of disease and / or insect infestations a serious problem for the tree may be stopped before it progresses to a full blown disorder.

Maintenance and correction of storm damage fall into this category.

3) Crown raising:

Simply put, this is the removal of lower branches to improve site lines near roads and to allow for movement of people and equipment under trees. Along city streets for example, many municipalities remove permanent tree branches to a minimum height of 16 feet from the ground or street surface.

Why?

Garbage trucks and other big rigs will prune the limbs by tearing them from the tree often causing irreparable damage to the main stem.

Along sidewalks, permanent tree branches should be a minimum of 8 feet above the sidewalk to allow for pedestrian traffic and snow removal equipment.

Depending where a tree is located in the landscape determines if branches are

Co-dominant leader split out by

snow load.

Photo by Josh Plunkett, U of M.

This hackberry stem was rup-

tured by a delivery truck hitting

a low hanging limb - see page 13

Photo: Dave Hanson

Page 13 Why?

raised or allowed to sweep to the ground.

Why?

Low hanging tree branches restrict movement and present poking and head-banging hazards in our yards and parks. So, in some instances the tree branches should be raised to allow people and equipment to move underneath

Putting this into Practice:

So, with those approaches outlined here’s a prediction – If you are responsible for a land-scape that contains trees – there is some pruning in your future…or there should be!

But hold on, before you grab the chainsaw, consider taking a brief course on pruning or at least read some of the current research on pruning trees. Unfortunately, there are still a lot of incorrect pruning practices taking place – bad pruning cuts, pruning practices that permanently damage trees and pruning performed during the wrong season for the tree.

Flush cutting:

There is a three cut method to pruning: cut number 1 is an undercut of the branch to pre-vent the bark and wood fibers tearing down the main stem. Cut number 2 simply removes the weight of the branch outside of cut number 1. The third and final cut removes the branch stub near, but outside of the branch collar. However, a person can still find litera-ture that describes the final pruning cut as follows:

“Then cut the remaining stub flush and parallel to the main trunk”

That is an exact quote from a currently available publication copyrighted in 1980. That description of the final cut is completely wrong!

Why?

The final pruning cut should take into consideration the branch bark ridge and the branch collar. Simplistically, the branch collar is a zone of fast growth and within this zone there are several protection mechanisms that protect the trunk of the tree from decay organisms that may enter the branch. By leaving the branch collar intact – the main trunk of the tree will be better protected from decay proc-esses…

A pruning cut that is “flush and parallel to the main trunk” leaves a large oval wound in the trunk tissue that a tree will have a difficult time sealing over with callus ma-terial. Protection zones and mechanisms are compromised and the tree is more likely to decay.

Topping and Tipping:

There are still companies topping trees and tipping branches on trees. There are still

The low hackberry limb that was

struck by a truck. See picture

on page 12 for resulting damage

to the main stem…

Photo: Dave Hanson

Top: Branch collar

Bottom: Proper pruning cut vs.

flush cut

Photos: Gary Johnson

Page 14 Why?

homeowners requesting that trees be topped and that branches be tipped. Both topping and tipping are harmful practices to trees…

Why?

Topping and tipping are pruning cuts made indiscriminately on limbs with no regard for placing the cuts near protection zones. These cuts almost always result in rapid decay of the remaining portion of the limb, while at the same time stimulating large amounts of new growth in the form of epicormic branches, also known as water sprouts. The new growth is typically poorly attached and begins to add considerable weight to a limb or branch being weakened by decay.

When to Prune:

How about the perennial question, when is the “best” time to prune a tree? Let’s turn that question around – when is the “worst” time to prune a tree? From the trees point of view the months of April, May and into June may be the worst time to prune.

Why?

First, this is the time of year when trees deplete their energy reserves and put most of it into new leaves. Pruning at this time places the energy that has been moved into branches, twigs and leaves onto the burn pile or into a landfill. This practice places the tree in a stressed state, with an energy deficit that may not be completely recovered in that season.

Secondly, this is an active time of year for many disease and fungal pathogens (Oak wilt for example). The warm spring months of April, May, and June typically bring high humidity from spring rains, these factors provide an ideal environment for many pathogens to flourish. So, you have the environment for a pathogen, you have a pathogen – now, to complete the “disease triangle” there has to be a host! How about that tree in your front yard that was just pruned, it is probably a good host for some pathogen. So, yes, spring can be a bad time to prune…

Another “bad” time to prune is late autumn into early winter...

Why?

Pruning in late autumn and early winter can lead to winter injury. The pruning wounds may not have time to “harden off” or prepare for winter. This can lead to deeper freezing in the tissues around the wound and in essence a larger wound can be created that the tree will have difficulty dealing with.

So that leaves us with the summer months and late winter (dormant season pruning). Typically late winter or dormant season pruning is the “best” time to prune.

Tree topping to allow would be

shoppers to see store front

signage..

Photo by Patrick Weicherding

“Worst” time to prune - during

the period of spring flower and

bud break through leaf set in the

early summer.

Blossom on leatherwood…

Photo: Dave Hanson

Page 15 Why?

Why?

During the late winter months (February and March), harmful pathogens are at a minimum, mostly inactive; therefore, this is a safe pruning environment from that standpoint. During this season, deciduous trees have hardened off and when the growing season begins the wounds will be sealed and the callusing process will be-gin.

Final Thoughts:

This brings us to another big question, should a homeowner hire a professional arbor-ist to do the tree work or get out there and do it by themselves?

Keep this though in mind; the balance of a tree or a tree limb can be difficult to judge. While, the task at hand may appear simple, tree work is a very dangerous profession.

One simple rule:

If there is a power line nearby – consult with an arborist.

Why?

Power lines and in-experienced, untrained workers do not mix!

At a minimum call the power company to discuss options… You may be able to schedule a line drop for a few hours. It is easier to physically disconnect and drop the line than to replace connections and repair damage after the tree falls the wrong way…assuming, you survive the incident and are able to repair the damage.

Some basic guidelines:

If the job requires a ladder, a consultation with an arborist may be in order.

Why?

By working from a ladder with a hand saw, chainsaw or even a pole pruner much of the necessary pruning cannot be accomplished and often the tree will end up be “lion’s tailed.” Lion’s-tailing leaves a tree with a reduced canopy, thus reducing its ability to photosynthesize. Arborists on the other hand will enter the tree with climbing gear (rope and saddle – NOT SPIKES) and or use a boom truck with a bucket to reach the tree top and branch ends.

If you think the job requires a chainsaw, consulting an arborist is recommended.

Why?

Chainsaws are tools for trained, experienced hands. Untrained operators often do more harm than good to both the tree and the operator. Most of the pruning that a tree needs can and should be accomplished with a “hand” pruner or pruning saw.

What or Who is an arborist? For more informa-tion visit www.isa-msa.org

Pruning disaster - a homeowner,

power lines, a ladder, and a

chainsaw…

Photo: Dave Hanson

Page 16 Why?

Exception: Yes, commercial / municipal arborists and tree-workers are trained in the use of chainsaws and will use chainsaws to complete a portion of their work. However, note that they also carry handsaws and use them appropriately.

If you have storm damaged trees, consult an arborist and the tree may be able to stay in the landscape, safely for years to come.

Why?

Trees that have suffered structural damage from storms or accidents will not “recover” or “heal” in the sense that our bodies will heal. Thus, arborists are trained to understand the structure of a tree and to understand how a damaged tree will respond to treatments. If possible cabling, bolting and bracing may be part of that treatment. But, most importantly an arborist can answer the question – “Can this tree safely remain in the landscape?”

If you are planning a landscape, please consult an arborist or a landscape designer.

Why?

It is important to select the right trees for your locations. Putting the right trees in the right places can dramatically reduce the costs of pruning and maintenance in your land-scape.

The bottom line is that feeling the need to prune trees does not make urbanites “control freaks”; rather, living in geographically condensed spaces in close proximity to mature trees renders us and our belongings potential targets to falling tree parts. Thus, out of necessity we need to care for our trees not only so that they are pleasing to look at, but so that they remain healthy, safe features in our landscape.

Why?

Because!

Works Cited:

Bedker, Peter J., O’Brien, Joseph G., Mielke, Manfred E., How To Prune Trees. United States Department of Agriculture, Forest Service Publication NA-FR-01-95

Mature Bur Oak…

Photo: Dave Hanson

Page 17 Emerald Ash Borer

DNR NEWS Indiana Department of Natural Resources 402 W. Washington St. W255 B Indianapolis, IN 46204-2748 For immediate release: April 22, 2004 Emerald ash borer confirmed in Indiana:DNR begins steps to contain spread. After receiving lab results from the U.S. Department of Agriculture, Department of Natural Resources officials confirmed that the emerald ash borer had infected a tree in Steuben County. This is the first confirmation of the ash tree-killing pest in Indiana. The ash tree-eating pest was discovered Monday at the Yogi Bear Jellystone camp-ground on Barton Lake in Steuben County about 40 miles north of Fort Wayne. The adult emerald ash borer is slender with a bright metallic coppery green color. It is about one-third of an inch long. The larval, or immature stage of the insect de-stroys live ash trees by eating the layers under the bark of the tree that supplies nutrients. After those layers are destroyed, the tree starves to death within a short time. Infestations are most easily identified by tiny D-shaped holes that are visible on the tree's bark. The bark may also develop lengthwise cracks or fissures. To date, millions of ash trees have fallen prey to the emerald ash borer and a num-ber of Michigan counties are under quarantine. The pest also has been found a few miles east of the Indiana border near Hicksville, Ohio and a few miles to the north in Quincy, Mich. State Entomologist Dr. Robert Waltz announced today that the state would begin to take steps to contain the spread of the infestation. The first step will be a survey of the infected area. The survey will determine, first, the number of ash trees that could serve as a host for the pest. Second, the survey will determine the extent of the infestation. Both of these steps are in preparation for trapping the emerald ash borer and the removal of all ash trees within a half-mile radius of the infestation.

Photo: Howard Russell, MSU

Above - Size of the adult insect

Below - The damaging larva

The adult insects D-shaped exit

hole

Photo: Deborah McCullough,

MSU

Bark fissure on green ash

Photo: James W. Smith

Page 18 Emerald Ash Borer

Further, Waltz announced the DNR is placing a quarantine on Jamestown Town-ship in Steuben County. The quarantine will forbid the transportation out of the township of any ash tree, including nursery stock, any ash logs or untreated lumber with the bark attached, and composted or un-composted ash chips or bark chips one inch or larger. Lastly, no cut firewood from any species of tree grown in Jamestown Township may be taken out of the township. DNR was first notified of a possible infestation by a local Purdue Extension educa-tor. A DNR field entomologist responded and confirmed an infestation but was un-able to confirm the presence of the emerald ash borer. Another DNR entomologist and a representative of the USDA's Animal and Plant Health inspection Service (APHIS) visited the site on Tuesday. They did confirm the presence of a similar wood-boring pest but could not visually confirm the emerald ash borer was present. The APHIS representative took a sample from the infected tree and sent it to an emerald ash borer specialist at the USDA's Systematic Entomology laboratory in Washington D.C. Wednesday the DNR received the lab results that confirmed the presence of the emerald ash borer. Waltz also suggests steps that Hoosiers should take to help retard the spread of the emerald ash borer to Indiana. "First, do not bring into Indiana firewood from Michigan or Ohio, particularly if the bark is still attached. In general, it is best to debark all firewood if you're traveling and be sure to burn all the wood you brought with you. Under federal quarantine, it is illegal to transport firewood from infested areas to any site outside the quarantined area." Finally, Waltz suggested homeowners can help by keeping their trees well watered and watch out for signs of this pest. "The emerald ash borer first attacks weak and troubled trees. Ash trees need an inch of water per week to remain healthy. It's important to maintain tree vigor," he said. Additional information about the emerald ash borer is available on the DNR Web site at: www.in.gov/dnr/entomolo/pestinfo/ashborer.htm Photos courtesy of United States Department of Agriculture, Forest Service web site: http://www.na.fs.fed.us/spfo/eab/img/img.htm

Photo: James W Smith.

Ash tree in decline

Photo above: James W. Smith

Galleries exposed and sprouting

at the base due to decline and

death of the upper portion of

the tree.

Photo below: David Roberts,

MSU - The galleries up-close

Page 19 Need a “small” Tree? - continued from page 1

Don’t be alarmed if the common name “Rowan” tree is unfamiliar to you. In the

United States this group of trees is more commonly referred to as mountain ash

and sometimes whitebeam (Sorbus aria). Worlwide there are approximately 100

species in this genus thriving in the cooler northern regions. American Mountain

ash (Sorbus americana) and showy mountain ash (Sorbus decora) are the more com-

mon species of the four species native to North America. The common name

“Rowan” traveled with the early Europeans and is more appropriately reserved for

Sorbus aucuparia, the European mountain ash.

Add Korean mountain ash (Sorbus alnifolia) to the three already mentioned and that

begins to cover the species provided in the nursery trade. But, a quick look at

nursery catalogs and in outlets reveals several selections showcasing a variety of

forms from columnar to oval that display subtle leaf, flower and fruiting variations.

Michael Dirr’s “Manual of Woody Landscape Plants” lists 8 species with the major-

ity of the nursery trade cultivars attributed to Sorbus aucuparia.

For the remainder of this discussion I will focus on the more common American

species American mountain ash (Sorbus americana) and showy mountain ash (Sorbus

decora). These trees tend to be on the smaller side, 15-30 feet tall with a 12 foot

canopy diameter. Thus, this tree can be a good choice for small yards and areas

requiring a small tree.

People are drawn to these trees due to several unusual characteristics. We’ll start

at the interior of the tree – the bark on the trunk is smooth (occasionally scaly)

and grayish-brown with significant lenticels. The form created by slender, spread-

ing branches tends to be oval.

Another significant feature is the foliage. The alternate, compound leaves tend to

be 6-9 inches long with an odd number (11-17) of finely toothed leaflets. Unlike

Sorbus aucuparia the serrations on the leaf margin almost completey encompass the

leaf. Fall color, while not spectacular, can be a fantastic addition to a landscape.

The fall colors range from yellow, yellow gold to reddish purple. But, what can

really set off the fall color is the presence of the sometimes persistent bronze fruit.

The fruit of the mountain ash is a pome or apple like and it is sustenance to a

April bud break above and fruits

persisting through the winter

below.

Above: Leaf of Sorbus aucuparia

Photos: Dave Hanson

Contact Phone Numbers Program Contacts: Gary Johnson – 612-625-3765 or grjonson@.umn.edu Dave Hanson – 612-624-1226 or dlhanson@umn.edu Mailing Address: 115 Green Hall, 1530 Cleveland Ave. North, St. Paul, MN 55108 Contacts: Regional Extension Educators: Bob Mugaas – 651-480-7706 Patrick Weicherding, – 763-767-3836 or weich002@umn.edu Gary Wyatt, 507-389-8325 or wyatt@umn.edu County Contacts: Carver County (Jackie Smith) - (952) 442-4496 or smith515@umn.edu Dakota County (Barb Stendahl) – 952-463-8002 or stend004@umn.edu Olmstead County – 507-285-8250 Ramsey County – 651-777-8156 Scott County (Jackie Smith) - (952) 492-5410 or smith515@umn.edu St. Louis County (Bob Olen) – 218-726-7512

TCAAG Members:

Additional Reference Contacts: Debby Newman (Info-U) – 612-624-3263 Don Mueller, DNR Forestry – 651-772-6148 don.mueller@dnr.state.mn.us Ken Holman, DNR Forestry – 651-296-9110 ken.holman@dnr.state.mn.us Paul Walvatne MNDOT – 651-284-3793 Paul.Walvatne@dot.state.mn.us Great River Greening – 651-665-9500 Tree Trust – 651-644-5800

Bob Condon – 952-890-1228 Mimi Hottinger – 507-388-4838

Paula Denman – 612-338-1871 Lisa McDonald - 612-721-2672,

Laurie Drolson – 651-464-9829 Betsy McDonough - 651-779-0437

Bruce Granos – 952-423-5211, Lu Schmidtke - 651-455-6125

number of bird species. Yet, if you can beat the cedar waxwings, ruffed grouse, European starlings, robins, common grackles and the pine grosbeaks you might be

able to produce a treat for your morning toast. Dirr indicates that S. aucuparia fruit is made into an alco-holic beverage, a juice, vinegar, stewed, made into a tea and is used medicinally. The species do differ sig-nificantly in the color of the fruit that is produced and it can be diagnostic for identification purposes. While American mountain ash fruit is orangey-bronze, showy mountain ash fruit tends to be red.

However, the characteristic that will really catch your attention occurs in early spring. The 1/3 inch, white flowers, especially on showy mountain ash, occur in flat topped clusters roughly 3-5 inches across that can be very abundant. When flowering is heavy against the dark green compound leaves, the trees can be spec-tacular.

So, why doesn’t every one plant one of these beauties? You might say there is an Achilles heel or several! The trees tend to be poorly branched with tight branch angles that are susceptible to storm damage. Mountain ashes prefer cool environments and in warmer urban environments are susceptible to cankers, leaf rusts, crown gall, scab, leafhoppers, and several other insects. One of the big problems for this species is fireblight. It hits the species hard. All in all, bringing this “cool climate” species into the urban setting predisposes them to a batch of problems that tends to reduce them to a short-lived landscape specimen.

If you have a good location and can keep the tree healthy – I for one would vote to give moun-tain ash a try!

Need a “small” Tree? -

continued