2003_Volume10_Issue4

Tre e C a re A d v i s o r N ew s l e t t e r http:// www.mntca.org

Dave Hanson and Gary Johnson, Managing Editors

Inside This Issue:

Volume 10 Number 4

Welcome Back Everybody! This Fall issue has been fun for me to pull together. I had the

Toxico - dendron Dave Hanson

1 opportunity to do a considerable amount of research and material gathering to pull to-

Quick Hits / Volunteer Opps Paula Denman

2 So, there is a chance that you have seen the article titled “Rooting Around.”

Putting Down Roots Cliff Johnson

3 should be aware of and yet, not many are. They are not plants for cultivated landscapes,

Arboricultural Myth: Mimi Hottinger

5

gether two articles. The first was requested by Beth Jarvis for the Yard and Garden News.

Secondly, I tackled a wild shrub and its cousin that everyone, especially outdoors people, but many of you volunteer in “Natural” areas - so, heads-up… This article also ties in with Cliff’s offering since these cousins are considered weeds.

Leaves of Three Quiz Dave Hanson

11 And what about shooting down another aboricultural myth. Mimi Hottinger throws out

Rooting Around: Dave Hanson

12

Fungi Targets Spruce Jim Sturgeon

18

Bug Plagues Widen Press Releases

19

Contacts

20

some info on street salt.

Enjoy!

Toxico - dendron By: Dave Hanson

have worked around poi-

Photos: Dave Hanson

sonous plants frequently.

Typically, this “Tree” ar- I can honestly say, I encounter poisonous plants ticle covers trees and shrubs that we desire to more often in the metro region than I do in the place in our yards, gardens, parks and other landscapes. I thought it

Boundary Waters Canoe Area Wilderness.

was time for a slight change, members of this

Let’s take a look at the

plant family deserve

title of this article

some coverage. Having

“Toxico” – “dendron.”

spent a great deal of time From Dorlands Medical in the field in Sherburne, Dictionary: Wright, Anoka, Isanti,

toxic(o)- (toxic(o)-) a combining

and Ramsey counties, I

form meaning poisonous or denoting relationship

Continued page 8

Page 2

Quick Hits TCA Mentors Wanted for the TCA Class of 2004 When you were new to the program, did you occasionally wish you had someone to ask questions of? Wonder how to find opportunities, or what to expect at planting projects, how to report hours, or need a second opinion on the answer to a question? Wouldn’t it have been just nifty to have had a mentor?

Since we don’t meet regularly as a group, it’s hard for new people to know who to call, so we’re offering the class of 2004 they’re own personal, experienced TCA to act as mentor. Well need one or two TCAs from each county. It won’t take much time on your part, but it could mean a lot to one of our newbies. Call Paula Denman at 612-338-1871 to sign up!

Become a Member of the Tres Chic TCA Advisory Group The Advisory Group has been around for a couple of years now. We’ve recently lost a couple of members and we’re asking for new TCAs to join us. This is your chance to help make the Tree Care Advisor program even better than it already is!

We meet for a couple of hours each quarter, and advisory group hours may be used toward your TCA volunteer commitment.

Topics previously considered - or up for future consideration – by the group include: bringing in other like-minded organizations as partners; asking TCAs to share their experiences in finding opportunities to fulfill their volunteer hours; the reputation of TCAs in the communities they serve; best ways to educate and update TCAs on an ongoing basis; the value of reference materials provided through the TCA newsletter mailings; and providing more volunteer opportunities for TCAs. Apply for membership to exclusive group by contacting Paula Denman at 612-338-1871. If you can't join us, please pass along any ideas or suggestions you'd like to share. We need all the help we can get.

Internet Notes: MnDOT has officially announced the opening of its Plant Selection Database. This database has been in the works for several years and it looks snazzy!

Check it out at: http://plantselector.dot.state.mn.us .

Have you visited the TCA website recently?

I keep it up to date with current photos and information. If you have anything you want to add - Let me know…

No access at home, Check out the website at a local library. They’ll help you!

The BIG bonus - You can see these Newsletters in color!

Page 3

Putting Down Roots Putting Down Roots

three feet tall and has

weed is a natural remedy

By Cliff Johnson, Carver/

smooth, oval leaves on

and preventative for poi-

Scott Master Gardener

tubular stems that grow to son ivy and many other more than 1-inch thick at

skin disorders. Results of

maturity. A member of the one study showed dra2003 nominated as - the

impatiens family, its stems

year of the weed

are brittle and loaded with people who used a jewel-

If each garden year has a theme, I would name 2003 as the year of the weed.

I read a story by a gardener who said she lost her garden. Her garden plot that began with such diligent planning and good intentions got lost some-

liquid.

matic results in 95% of weed tincture for poison

Its trumpet-shaped yel- ivy rash. Jewelweed works low flowers hang from the by counter-reacting with

plant much as a jewel from the chemicals in other plants that cause irritation. a necklace. The seeds “pop” when touched, giving rise to the plant’s other name, touch-menot.

The problem with jew-

When you are out in the

not (Impatiens pallida).

field and find you have

Photo courtesy of:

been exposed to poison

William S. Justice @ USDANRCS PLANTS Database

ivy or stinging nettle you can reach for the jewel-

weed plant and slice the where about July amongst elweed is that it eventually stem, then rub its juicy the weeds. grows everywhere. I don’t inside on exposed parts. think jewelweed was preMy college horticulture This application will resent on my property when professor defined a weed portedly ease irritation I moved here 11 years as a flower out of place. I and prevent breakout. ago.

I first noticed it a half haven’t forgotten that defiThe lambsquarter got dozen years ago in the nition but some weeds smuggled into my garden don’t live up to the flower shade of my back yard.

Like most weeds, it proba- hidden in bags of comcompliment, in my opinbly hitchhiked here in the posted sheep manure. ion. soil of some other plant I Each spring I mix soil for My most pervasive bought or transplanted or containers and transplantweed problems this year ing by blending sterilized got deposited in bird are jewelweed and lambtopsoil, peat moss and droppings. Jewelweed squarter. thrives in moist, shady ar- composted sheep manure.

Jewelweed is actually a rather nice plant. It is an annual that grows up to

eas, which I have in abundance.

In its defense, jewel-

Jewel weed or pale touch-me-

This year, every container I planted, along with plants

Continued page 4

Goosefoot family Above: Lambsquarters (Chenopodium album) Below: Autumn seedlings of lambsquarters and pigweed

Page 4

Raspberry (Rubus idaeus.) on a frosty September morning in Anoka County.

Putting Down Roots:

continued

placed in garden beds,

berry would be one of the definition is appropriate

have robust crops of tiny

aces. Year after year it

for some weeds. Wild vio-

lambsquarter seedlings.

shows up everywhere. It

let and Virginia creeper,

The seedlings are easy to

does little good to pull up

for example, grow every-

pluck out of the containers the new shoots because

by hand but it’s a nuisance. they are attached to a vig- half. I have learned to acI’ve just learned the

orous underground root

name of another weed I’ve system that sends up thorny new raspberry been fighting in recent years. It grows in shade under other plants. An

plants a few days later. I could lose my gardens to

internet search helped me wild raspberry in one growing season if I didn’t identify this weed as Galium aparine, with a curious keep at the chore of upcommon name catchweed rooting this menace. bedstraw. Catchweed is a

Galium aparine - catchweed or cleavers.

Douglas Ladd - USDA SCS 1991 USDA-NRCS PLANTS Data-

where on my acre and a cept them as one learns to accept a facial scar or chronic limp.

One reason weeds are so hard to control is because they’re so darn old.

Weeds are among the oldest living organisms and they didn’t get that way by

The problem with most being stupid. A Canadian

tangling plant that can

weeds is that they grow

grow to 80 inches long.

right amongst all the desir- propagated Arctic lupine

botanist successfully

The leaves are narrow and able flowers and vegeta-

from 10,000-year-old

are in a whorled arrange-

bles, prohibiting tidy con-

seeds that had been frozen

ment around the stem.

trol with chemicals. Get-

in silt in Canada’s Yukon

base

Leaves and stems are very ting rid of weeds, in most

Territory. In another

Woodbine or Virginia creeper

rough to the touch due to cases, requires hoeing or,

study, a Michigan scientist

(Parthenocissus quinquefolia) is

the presence of short, stiff in really tight spaces, pull-

mixed weeds seeds with

hairs that make the plant

sand in a milk bottle and

really quite an attractive climbing plant..

ing individual stems. On a

attach to clothing and ani- cool, breezy day, pulling

buried the bottle, bottle

mal fur. The description

mouth downward, in

weed seedlings isn’t too

said catchweed is a serious bad a job. But -- and this is 1879. Some of the seeds problem weed in culti-

not news to gardeners -- it sprouted when planted

vated fields, particularly in is no fun at all when the hay or grain.

If I were to create a

air is hot and still and the mosquitoes are swarming

deck of cards featuring the in search of their next blood meal. faces of my 52 biggest weed enemies, wild rasp-

The flower-out-of-place

100 years later.

Page 5

Arboricultural Myth: Winter Thinking for Spring Trees By: Miriam Hottinger

De-icing salts are chemicals

Two components of the above

that are used on roads and side- salts, sodium and chloride, inAs spring bounds out of the winter doldrums, memories of cold, snowy days and street salt seem far from what people want to think about. But decisions made about what trees to plant in the spring can come back to haunt homeowners come winter because of the varied impact that street salt and other street-clearing applications have on different trees.

Many people believe that de-

walks during the winter months terfere with nutrient intake and for safety. They enable water to slow the growth of trees and remain liquid at temperatures

woody plants. Sodium also ac-

under 32 F. Salts penetrate the

cumulates in the soil and can

snow and ice in a vertical move- destroy the structure of the ment. They loosen the packed

soil, which can impede root

snow and ice, and make shovel- growth. ing or plowing streets and sidewalks easier.

Not All Salts are the Same The five common de-icers are calcium chloride (CaCl),

Alternatives to Salts Sometimes materials other than salts are used in street clearing efforts. Urea is a fertilizer occasionally used as a de-

sodium chloride (NaC l), potas- icer. It will burn plants if applied

icing salt or street salt is harm-

sium chloride (KCl), urea, and,

heavily and, as with calcium

ful to all trees. However, re-

calcium magnesium acetate

chloride, expense is a concern.

search has shown that not all

(CMA). Although de-icers can

Potassium chloride is a naturally

salts have the same effect on all

be used alone, they are often

occurring material that has

trees. Some trees can withstand blended. Sodium chloride and the harmful effects of these salts calcium chloride are the most

about the same effect on plants

and some salts are more damag- widely used salts. Sodium chloing than others. Scientists, for- ride, the cheapest, is the most

magnesium acetate is a new

as sodium chloride. Calcium salt-free melting material, made

esters and city managers are

frequently used, but is the most from dolomitic limestone and

constantly looking for new al-

damaging to plants. It has been

acetic acid. Research has shown

ternatives to keep trees safe

used as a de-icer since the

that calcium magnesium acetate

and to keep streets de-iced.

1940’s. Calcium chloride is

has very little effect on plants

more expensive than sodium

and soil. It is currently being

chloride and is not used as of-

used in environmentally sensi-

Nearly 300,000 tons of deicing salt is applied to Minnesota highways each winter. Not only are highway trees damaged, but trees in urban areas as well can be affected. Living in Minnesota we have very little alternative but to learn how to deal with the damage that occurs with the use of de-icers.

ten. Some highway departments tive areas such as wetlands adjaspray liquid calcium chloride over sodium chloride to lower

cent to roads.

Abrasives like sand, grit and

the melting temperature. Cal-

cinders are also used for street

cium chloride is effective as a

clearing, but primarily for trac-

de-icier at lower temperatures

tion. Some melting can occur

than sodium chloride, and is less with abrasives in conjunction toxic to plants, but if heavily with the applied it can burn plant foliage.

sunshine.

Continued page 6

MNDOT Snow Plow - The high tech truck.

Photo courtesy of http://www.betterroads.com/ articles/brapr99b.htm

Page 6

Arboricultural Myth: When used alone they pose no

and volume of the traffic. The

same symptoms as many other

threat to woody plants and

most severe damage of drift is

stresses and disease, such as

trees, but sand is often mixed

within 60 feet of the road.

early changes in fall color, early

with chemicals to prevent the

Trees may be affected by

leaf drop in fall, and wilted or

sand from freezing.

salts in many ways. Salts can

brown leaves. The damage will

De-icers Impact Trees in a

cause plant water loss be-

not become evident until the

Variety of Ways

cause the salt solution in the

growing season after the expo-

de-icers can be transported to

soil is highly absorbent, decreas- sure has occurred. Some of the symptoms of salt spray on deing the amount of water for

the air and soil. The most fre-

roots. They can result in chlo-

quent ways are spray-drift and

ride poisoning when the chlo- clude bud death, twig die back, and a deformity called witches ride is absorbed by the roots

There are several ways that

De-icers were brought in by the runoff. After application, the salt truckload around this apartment stays on the road until it dries. building after a pipe burst near a It can then be suspended by the fountain. The following season,

ciduous trees and shrubs in-

and carried to the leaves by sap, broom, where small clusters of twigs are produced at the end allowing salt to accumulate to of branches.

movement of the vehicles and

toxic levels. Salts can lead to

died, had thin crowns, scorched

blown off the road. The air-

soil damage because sodium

leaves and generally did very

borne salt lands on the ground

changes the structure of soil,

tion from increased salt in the

poorly.

or foliage of the surrounding

making it less permeable and

soil due to runoff will appear

trees and shrubs. Runoff is

hampering root growth. They

similar to drought, beginning

irregardless of species, trees

The damage done to vegeta-

caused by the salt staying on the can lead to nutrient loss when with yellowing and wilting of leaves. Foliage on deciduous streets, highways, sidewalks, and excessive sodium in the soil driveways until it rains, or when restricts the tree’s root systhe snow or ice melts and runs tems’ ability to absorb potas-

Witches brooms from salt dam-

hour roadways.

Above: River Birch Below: Bur oak

(brown and dead) around the

off in solution. This solution

sium and magnesium needed for margins of the leaves, and coni-

either flows off the road into

photosynthesis. And the freez- fers will have needle tip burn

the soil or is sprayed and

ing of salt spray on twigs

age. Both specimens located on splashed onto the trees and soil and buds can cause salts to the east side of 40-45 mile per

trees can appear scorched

(browning on tips which can be seen as early as late February or

as traffic moves along the high-

enter the pores and weaken the early March). There may be an

ways.

resistance of some species to

abnormal change in color. With

cold temperatures.

increased salt loads, progressive

The impact de-icers have on ber of factors, including prox-

According to Gary Johnson, a symptoms will be early fall color, reduction in leaf and professor at the University of

imity of the plants, soil type,

Minnesota, it can be very hard

vegetation depends on a num-

flower size, defoliation and

stunting. With both drift and topography, amount and kind of to diagnose salt injury.

(University of Minnesota Exten- soil accumulation of salt there is de-icers applied, and the plant a decline in the plant’s general species. The amount of de-icer sion Service News and Informahealth, this decline makes them transported correlates with the tion.; Jan. 31, 2003) Saltmore susceptible to insects and damaged trees can have the amount being used, the speed

Page 7

Arboricultural Myth: diseases.

abrasives such as grit, sand or

Tree Choices Can Make a

CMA. Plant trees in areas with

Difference

good drainage to avoid standing

Not all plants are affected in

in contaminated salt water.

the same way. Some trees have

Avoid high-risk sites where salt

a genetic makeup that makes

accumulates in the soil and, if

them more sensitive to spray

possible, flush (thoroughly soak)

while others are affected more

the soil with water after the

by the accumulation of salts in

frost is out of the ground. Main-

the soil. Young, less-established

tain tree health all season: wa-

trees and older less healthy

ter when necessary, prune

trees are more susceptible than properly, avoid mechanical middle-aged trees. Young trees wounding of trees, and avoid also absorb larger quantities of

soil compaction. If you need

Salt injury - marginal leaf burn or scorching can be a result of high salt accumulation in the soil.

Graphic from : Minimizing De-Icing Salt Injury to Trees Gary R. Johnson and Ed Sucoff

chloride than older trees. Trees help in selecting the right tree for your yard you can contact that are structurally sound – with no wounds or decay – are

the University of Minnesota

better able to withstand the

Extension Service. There are

salt.

also several websites to help

What can property owners and landscapers do to help protect trees and shrubs to minimize salt injury? First, it is important to plant trees and shrubs that are appropriate to the salt exposure expected.

Avoid planting trees that are

you in selecting the right tree for your yard: www.extension.umn.edu/ distribution/naturalresources/ DD1413.html#Minimizing and www.cce.cornell.edu/monroe/ cfep/ factsheets/18roadsalttrees.html.

sensitive to drift and soil accumulation. If the trees are within

When homeowners and city

the 60-foot area of usual drift

managers follow these preven-

from highways or streets and

tive measures the damage of de-

trees are sensitive, erect a solid icing salt will be minimized.

Trees are not only a pleasant barrier or wrap with burlap. If possible, reduce the amount of

sight to view, but with proper

de-icer and reduce the distance

care “the right tree in the right

the de-icer will be thrown. En-

place” will survive a Minnesota

courage your community to use winter and give you years of less harmful products including enjoyment.

Tolerant of Salt Spray Horse Chestnut (Aesculus hippocastanum).

Above - Leaves and spiny chestnuts in September.

Left - Attractive flower spike in mid May.

Page 8

Toxico - dendron: continued to poison. dendron – From the greek word for

ence with me.

can be found in almost any

tree. [toxico- + Gr. dendron tree] toxi-

How many of you, as vol-

codendron.

unteers, have worked on

Rhus toxicodendron is the old genus / species binomial for poison ivy. Recently, the “Rhus” genus name has been replaced with “Toxicodendron” for several related plants. The Poison ivy patch in Anoka County - note the yard stick to the right. The plants are a good

new naming convention separates the poisonous

foot taller than the yard stick

members of the family,

(dashed line).

“Anacardiaceae,” from the “Rhus” sumacs that we place in our landscapes

Poison ivy leaf - Leaves of three.

Poison ivy seed.

sandy prairies. Poison ivy

buckthorn removal pro-

well drained habitat in Minnesota, from swamp edges, forest edges, and

jects or helped plant a

prairies to roadsides and

you start dragging brush

outside of Minnesota, say

wrapping your arms

vines in the trees, hence

bunch of trees and shrubs fencerows. And hey, if you venture outdoors – in a natural area. When

away from a site – do you in southern Wisconsin or really know what you are Iowa, watch out for those around? I’ve had a number of friends come into contact with poison ivy while dragging brush be-

the IVY part of the name.

As one travels south and east into more temperate zones, poison ivy becomes

hind a cutting crew. Many quite the climber. So, simply did not know what keep that in mind if you

poison ivy or for that mat- encounter a three leaved Every year people working ter poison sumac looked climber, poison ivy is likely in the outdoors encounter the character and it inlike. So, it is no surprise toxic plants and are not spired the childhood song, that after the plant has aware of the encounter been through a chainsaw “leaves of three, turn and until a blistering rash apor brush cutter blade they flee.” pears. Lately, my encounwere even less likely to ters have involved an inrecognize it.

Poison ivy has alternate termediary – my wonderbranching and three leafful four-legged friend, Poison ivy (Toxicodendron lets which may have entire Lady. Amazingly enough, margins or slightly notched radicans a.k.a. Rhus radimost animals are not afcans), in Minnesota, has a margins or margins with fected by the oils few coarse teeth. Poison woody stem that is typi(Urushiol) from the poison cally less than two feet tall. ivy has whitish (ivory to plants – but my dog hapgray) fruits that originate However, don’t be surpily returns from her prised by the 3-4 foot tall in the leaf axils on an erect romps through the ivy stems out there in the dry fruiting structure. patch to share the experi-

Page 9

Toxico - dendron: continued So, you really know your

but it grows in the

woods-lore and you rely

swamps and lowlands

on the little ditty “leaves

with the likes of speckled

of three, leave it be” or

alder (Alnus rugosa). Poi-

“leaves of three, turn and

son sumac has alternate,

flee.” Well, that’s very

compound leaves approxi-

good and useful until you

mately 7-14 inches in

encounter poison sumac

length with 7-13 leaflets.

(Toxicodendron vernix a.k.a. The leaflets themselves Rhus vernix). Luckily, in

have entire to slightly

areas of the United States

wavy margins and are 1½

________ (insert your

where poison sumac can

to 5 inches long, opposite

favorite poison plant) is

winterberry (Ilex verticillata), and

be found, most people

on the petiole, shiny dark

the best way to end up

ferns...

don’t venture into the

green above and pale be-

with a blistering rash. Or

swamps and wet places

neath. Look for the fruit

go ahead and cut the of-

that poison sumac likes.

and flower structures to

fending plants and handle

So, keep your eyes peeled be on some of the plants,

the cut, broken stems,

when you are working in

not all, as the plants are

leaves, sawdust or fruits

that vegetation type. Poi-

distinctly male and female. (sounds like dragging

son sumac is in Minnesota! The fruit is a very characAnd the scary part is that

Poison Sumac habitat - a swampy moist area with alder,

brush). Breaking the plant

teristic pendent panicle of exposes one to the afflict-

poison sumac can be up to ivory colored spherical

ing agent – Urushiol.

15 feet high, commonly I

berries less than ½ inch

However, seldom are wild

encounter it around 5-8

thick. The fruit panicle

plants “unbroken” and

Poison sumac shrub branch at

feet – right in one’s face.

originates in the leaf axils.

simple contact is all that is

about 7 feet. Note the com-

When walking through a

Poison sumac’s fruit struc- required to get the oil on

swampy area take a look

ture, smooth leaves with

our skin.

at those shrubs before you entire margins and its prefbrush past them or reach

erence for the swamp life

up to push them out of

clearly separates it from

the way.

other similar appearing sumacs.

There are several other methods of transfer to keep in mind. Soil under a patch of poison ivy or sumac can carry the agent –

Poison Sumac is a woody shrub that in many ways

Crashing your way

water standing beneath or

resembles other sumacs,

through a patch of poison

simply flowing past a plant

pound leaves and pendent seed.

Page 10

Toxico - dendron: continued may float the oil to an un- believe that the fluid from

Photographs of poison su-

suspecting individual. And broken blisters also

mac were taken in and

yes, it is true that burning

spreads the rash. This is a around the Boot Lake Sci-

poison ivy or poison su-

fallacy; it is simply delayed

entific and Natural Area in

mac does release urushiol contact with the reactive

Anoka County. This natu-

into the smoke and it can agent over a period of

ral area on the western

then be breathed into

time that results in latent

border of Carlos Avery

ones airway and lungs.

reactions or rashes.

Wildlife Management Area has a healthy population of

Urushiol is an oily sub-

Ok, these plants do have

stance and is quite difficult one redeeming quality.

poison sumac. Poison sumac is easily viewed in this

loosen the agent only to

Believe it or not, this qual- natural area from the ity has brought poison ivy road, no swamp slogging

allow it to resettle on an-

to some of our friends

to remove. Many soaps

other part of the body.

Clothing, tools, pets and many other animate and inanimate items can carry

required – unless you are

around the globe as a gar- like me! The poison ivy den plant. Both poison ivy photos also were mostly

and poison sumac can pro- taken in and around Anoka County Parks and duce brilliant fall colors.

newed reactions days and

The reds and golds should, trails. If you somehow did not become familiar with in my opinion, be there

years later.

throughout the growing

the oil around causing re-

season to warn away the Once on the skin – it is the urushiol that causes the allergic reaction. It can be a few hours up to days before a reaction is

unwary. Right now, this last week of September

and visit Anoka County – we’ll share some plant

these plants do put on a pretty good show. Leaf

you may be moving the urushiol from place to

It is accepted practice to

place on your body. The

leave these plants (poison

result: different reaction

ivy and poison sumac) in

sites initiated at different

natural areas as these

is what has led people to

or adult life – come out

and on into early October knowledge with you.

evident and all of this time collectors be aware.

times – this phenomenon

these plants in your youth

In the spring issue I plugged one of my new favorite products “tecnu” and gave a brief snip-it about poison ivy. That brief snip-it planted the seed for this article and

plants are part of that eco- the accompanying “Leavesof-Three” quiz. system. For this article,

“Leaves of Three�: Quiz Answers - Page 20

Page 11

Photo 2 - Leaves of three - yes. Spiny, woody stem with leaves alternate.

Photo 1 - Leaves of three - yes. Opposite branching, compound leaf, leaflets toothed.

Plant about 2 foot tall. White film on the green new stem.

Photo 4 - Compound leaves, usually more than 3. Opposite branching - Same as Photo 1.

Photo 3) Three different plants - all have leaves of three.

Left - Small vine with entire leaf margins found in forest under-stories.

Center - Woody plant with a spiny stem and toothed leaves, prominent veins.

Right - Woody stem with smooth, shiny, green notched leaves.

Photo 5) Leaves of three - Do we stay away? Notice the variability in leaf margin. Almost completely entire (smooth) and oval to notched and pointed.

Page 12

Rooting Around: Tree Roots

Graphic from The Morton Arboretum web

Rooting Around: Tree Roots By: Dave Hanson Take a good hard look at your favorite tree. What do you see? Nice form, leaves, branches, bark, but, how many would respond – “Oh baby! There must be some fine roots holding up this tree.”

Unfortunately for trees, not too many people respond in this fashion, the world underground does remain a mystery. What is happening down there? What are tree roots and for that matter where are the roots? Why and how do roots get into sewers, cause foundations to crack and sidewalks to lift? The reason that these mysteries remain: we cannot easily see and touch tree roots, we cannot readily access them and typically we do not encounter them without getting out a shovel. This brief article will skim the surface, so to speak, and attempt to provide some insight and answers to these questions.

Large perennial, support roots of a bur oak exposed by erosion.

So, let’s start at the beginning and address two basic questions. Question number one, what are tree roots? There are three basic types of tree roots: Structural support, Fluid transport, and nutrient / moisture absorbers. Structural support comes in the form of largerdiameter perennial woody roots that anchor the tree to earth. Near the base of the tree are found the sinker or striker roots that help stabilize the tree and help it exploit deeper soils, but they seldom extend below 1 meter deep (Harris et al.). A second group of perennial support roots grow horizontally radiating away from the tree and also provide transport of nutrients, water and oxygen to the canopy. In return, the canopy delivers energy back to the roots for their use and for storage. The last of the basic root structures to discuss here are referred to as absorbing roots (fine root hairs and the root tips roughly 1/16th inch diameter) that provide nutrient and moisture absorption for the tree.

With that basic understanding, let’s move on to question number two. Where are the roots of a maturing or mature tree? Many consider the drip-line of the tree to be the limit of the root spread; therefore, the assumption is made that this is the area to fertilize and water for the benefit of the tree. A better mental picture

Rooting Around:... continued

Page 13

to form is a wine glass positioned on a dinner plate. In support of this mental picture six species, including green ash, maple, and oak, were studied by Dr. Edward Gilman of the University of Florida. Dr. Gilman and associates performed root growth trials in Florida and New Jersey. The findings clearly debunked the “drip-line” notion of tree roots. On average they found that tree roots extended 3 times the spread of the branches and that more than 50% of the absorbing roots were beyond the drip-line.

Several numbers can be found in the literature concerning where the bulk of fine, absorbing roots are found in the soil profile. The stated depths range from the top 24 inches to the top 18 inches with 50% of the fine roots being in the top 6 inches of the soil profile. Dr. Gilman’s research tightens these numbers up considerably. From the same root growth trials in Florida and New Jersey Gilman states: “fine roots are concentrated in the top 12 inches of soil with many in the top 2 inches.”

Graphic from Tree Roots, ISU Forestry Extension

Okay, so some trees have roots near the soil surface to collect nutrients and moisture. “But, I’ve never watered my tree because its taproot gets all the water it needs from the Saint Peter sandstone aquifer.” There are species that as seedlings produce and rely on tap roots, but quite honestly, as “tap-rooted” species mature, tap roots become insignificant in the overall root structure. The bulk of nutrient and moisture uptake is taken over by the absorbing roots near the surface.

Tap roots and other “sinker” roots can penetrate into the soil layers, but research indicates that depth of rooting is dependant on soil-oxygen. Dr. Kim Coder from the University of Georgia states that good root growth requires a soil atmosphere of 15 percent oxygen. He continues by saying that below 5 percent soil-oxygen, root growth will stop and below 2% roots begin to decline and die. Dr. Coder describes the advancing root tips existence as quite precarious and more of a “good news / bad news” scenario. If the root progresses too deeply, oxygen deprivation will be an issue and on the other extreme if a root progresses too shallowly, a dry spell will likely cause its demise. As a matter of fact, this precarious situation translates into a short life span for an absorbing root with the root tip being replaced many times per growing season.

University of Minnesota, TRE nursery Planting Depth Study. After three years in the ground, these linden root systems show the results of being planted ten inches too deep. Note the roots returning to the surface – Speculation: the roots were growing towards a higher soiloxygen concentration.

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Rooting Around:... continued The bottom line, unlike horses, roots do not smell water. Along the same line, roots do not seek water. Instead, roots tend to grow where the growing is good and the growing tends to be good in the top 12 inches of soil where temperature, moisture, nutrients and more importantly soil-oxygen are usually adequate. To underline the fact that roots are opportunistic “absorbers” – there has been a push lately to discourage calling fine absorbing roots, “feeder roots” simply because the term “feeder” implies an aggressive, hunter-gatherer approach to seeking life’s necessities. Roots simply follow the moisture gradient of the surrounding soil and continue to grow where the growing is good. Meaning that roots tend to grow where there is a good supply of moisture, nutrients and of course soil-oxygen.

Now is the time to step back and put this information in perspective.

Tree roots require oxygen to remain viable and soil-oxygen decreases the deeper in the soil profile that a root penetrates. Add in soil compaction to your thought process. By compacting a soil the pore space is reduced which in turn reduces the amount of soil-oxygen that can be present. Okay, one more thing – re-landscape the lawn with a bobcat and add 4 inches of soil to bury the roots a little deeper. Hold on, the lawn typically means turf and that means roots from grass and competition for moisture, nutrients, and you guessed it soil-oxygen. The picGraphic courtesy of: Univerture should be coming clearer, tree roots, all too often overlooked, spread as far and as wide sity of Minnesota Extension Service. as they can in compacted soils and at depths below 12 inches trying to survive. Keep in mind that this is biology, and the ultimate root structure depends on many factors below ground.

Site conditions, compaction, excess fill, flooding and infrastructure have direct and indirect impacts on soil moisture, soil oxygen, soil texture and structure.

Moving on into the second round of questions: It has happened again! Another basement floods because a sewer line has been clogged by tree roots. Maybe this time it is another foundation or sidewalk being moved or lifted by tree roots. Are trees “perpetrators” of these acts or is it simply guilt by association. One side of the argument states that the tree and its roots are not at fault, but rather there is fault with the design or construction of the infrastructure.

Honesty is probably the best policy; trees are not as innocent in the above scenarios as many of us would like to believe. However, why has the tree become the guilty party? Design error is often the only answer to be arrived at whether it is the landscape design or the engineering design. Let’s face it, trees require space for rooting and resource exploitation, if a tree root happens upon a nice moist, oxygenated resource-rich environment (a sewer line for example) where it can thrive and perform its duties – it will. In commenting on tree roots in sewers Richard Harris et al. states “the conditions of aeration, moisture, and nutrients are so favorable that it inevitably grows until it clogs the sewer.” The question in many minds still remains as to how the root happens upon the sewer line.

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Rooting Around:... continued Martin Mackenzie of the US Forest Service recently spoke to a conference audience describing the “battering-ram” root that breaks through even the toughest sewer lines and concrete blocks. Of course this statement was “tongue-in-cheek.” Roots grow quite slowly and don’t have much chance to hurl forward with any great speed. In the case of finding a sewer line there is both speculation and research that explains the encounter. Speculation from Harris et al. is that in some instances sewer line trenches are compacted to a lesser degree than the surrounding urban soil. Thus, homeowners may unwittingly take advantage of this and plant trees in the trench or perhaps the tree roots will encounter this less compacted environment and continue to grow into it unimpeded. Dr. Kim Coder researched the thermal gradients that exist between sewer lines and the surrounding soils which allow two things to happen. One is a moisture condensation layer on the sewer line itself. Secondly, a moisture condensation column develops in the soil layers above the sewer line. Once a tree root encounters this moisture condensation column it grows downward (providing adequate soiloxygen exists) along the increasing moisture gradient in the soil toward the sewer line.

Upon encountering the sewer line, the root tips continue growing towards more favorable conditions, eventually a root tip may find and exploit a crack or fissure in the sewer line.

Hence, back to the argument proclaiming faulty infrastructure – “the root tip exploits a crack or fissure in the sewer line.”

Once the root tip has entered the line, the real damage to the line can begin. The tree roots tend to form a mass of root tips that slow the flow enough to allow sediments to be trapped, thus clogging the line. Or the root may begin to develop as a woody, perennial root and exert pressures that may crush or burst the sewer line.

Larger, woody, perennial roots exert substantial radial pressure and over time can displace man-made structures. The perennial root increases in diameter by adding a growth layer every year. Commonly, sidewalks are lifted by this type of radial growth. Displacement of structures can be caused by horizontal roots growing under a slab concrete floor or sidewalk or by a vertical “striker or sinker” root growing downward next to a foundation. In any case the root growth is slow and forces can be substantial enough to displace or otherwise damage structures.

Tree roots from a silver maple pushing up an asphalt walkway.

Another mechanism by which trees cause structural damage involves the presence of expansive clays. Expansive clays respond to soil moisture changes by expanding and contracting.

Man-made structures often rely on the surrounding soils for additional support. If a tree’s roots encounter this “support soil” of expansive clay the moisture regime can be dramatically altered by the evapo-transpiration function of the tree. The clay soil type can be dried excessively causing it to contract, thus shrinking away from the structure it is supporting.

The literature identifies several tree species as “culprits” in the “aggressive” root depart-

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Rooting Around:... continued ment. The following species are on a “Not Recommended for Planting” list maintained by the Michigan Department of Natural Resources as those having invasive rooting habits: silver maple (Acer saccharinum), white mulberry (Morus alba), white poplar (Populus alba), Eastern cottonwood (Populus deltoides), weeping willow (Salix alba), black willow (Salix nigra), and American elm (Ulmus americana). Is it necessary to “label” these trees as culprits and black list them? A better approach is to pay attention to putting “the right tree in the right place.”

More and more attention is being paid to tree selection since it is the “key” to a trees long life. Site conditions truly need to be considered prior to starting the species selection process. It isn’t always successful to fall in love with a species and then try to fit it in our landscape.

In wrapping all of this together, a number of additional questions come to mind? For instance: •

What does all of this say for our notion of watering and fertilizing within the drip-line?

Yes, the water and fertilizer helps, but in light of root plates reaching well beyond the crown - consider expanding the applications to a broader area.

•

With a tree’s absorbing roots concentrating near the soil surface, how well do the trees and turf co-exist?

Trees and turf are in a competitive battle for resources and let’s face it – turf is a tough competitor. From a trees perspective: The more lawn that can be replaced with mulch the better.

•

What does this portray for trees when parking lots, sidewalks, driveways, buildings, roads and other infrastructure are placed in close proximity to trees?

These structures almost always require a compacted base layer to provide additional support for the impervious surface being applied. The needs of the tree and the reach of the root plate are too often ignored leaving trees with reduced stability and with reduced capacity to uptake nutrients and moisture.

There is some good news out there… Recent methods of constructing sewer lines have dramatically reduced the potential for root intrusions. Longer sections of less porous pipe are being used for constructing sewer and water lines. This helps cut down on the conflict between tree roots and sewer lines that often results in a large, mature tree being removed.

Researchers and trials in California are looking at composite sidewalk surfaces that flex, thus giving trees room to grow and more soil to exploit for resources.

Researchers at Cornell University have been testing and working with CU Structural Soils® for some time. These soils are compactable, yet allow tree roots to penetrate. Placing these structural soils in the rooting zone under sidewalks, pavers, parking lots, roads and other structures allows trees to expand root plates farther.

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Rooting Around:... continued

So, next time you look at your favorite tree – give some thought to the root structure. You may not have the, “Oh Baby!” type of reaction, but after reading this article the roots should at least be creeping into the outer recesses of your mind.

For More Information: Bassuk, Nina. Cornell Structural Soil. Internet. Available 9/25/2001. http://www.hort.cornell.edu/department/ faculty/bassuk/uhi/outreach/csc/ Coder, Kim D. Tree Roots and Infrastructure Damage. Internet. Available 9/25/2001. http:// www.forestry.uga.edu/warnell/service/library/for98-008/index.html Coder, Kim D. “Don’t Stumble Over Surface Tree Roots” Grounds Maintenance. August 1 1998 Gilman, Edward F. Where are Tree Roots? Extension Service Bulletin ENH 137, Florida Cooperative Extension Service, University of Florida, Institute of Food and Agricultural Sciences. Internet. Available 9/25/2001. http:// edis.ifas.ufl.edu/BODY-WO017 Harris, Richard W., Clark, James R., Matheny, Nelda P., Arboriculture: Integrated Management of Landscape Trees, Shrubs, and Vines. Third Edition. Prentice-Hall, Inc. 1999.

Graphic, ISU Forestry Extension. Tree Roots October 2001. Internet. Available 9/25/2001. http://www.ag.iastate.edu/departments/forestry/ext/roots.html Graphic, The Morton Arboretum, Internet. Available 9/25/2001. http://www.mortonarb.org/research/treeroots.html Pool, Bob. “With Rubber Sidewalks, Trees Are on the Rebound,” LA Times.

14, July 2001. Internet. Available 9/25/2001. http://www.mindfully.org/Plastic/Rubber-Sidewalks.htm Randrup, Thomas B, McPherson, E. Gregory, Costello, Laurence R. “Tree Root Intrusion in Sewer Systems: Review of Extent and Costs.” Journal of Infrastructure Systems, Vol. 7, No. 1, pages 26-31. March 2001.

Soil Compaction: Causes, Effects, and Control. 2001. Internet. Available 9/25/2001. http://www.extension.umn.edu/distribution/cropsystems/ components/3115s01.html

Eastern Cottonwood (Populus deltoides) root forming a garden border.

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Fungus Targets Varieties of Spruce Trees Across County

By Jim Sturgeon

Bob Wright, quoted in this article, is an Ottertail County MG

“The Daily Journal�

Fergus Falls, Minnesota.

been affecting spruce trees for many years. He said the disease is likely not any worse now than before.

correctly. However, severely infected trees usually require two or more years of fungicide applications.

Application to large trees requires special equipment to and TCA. ensure adequate coverage.

Wright said currently, there is only one person in Otter Tail Fortunately, the disease is The disease, called RhizosCounty who does that type of phaera Needle Cast, is caused treatable. But the treatment is spraying. time-sensitive. Treating the by the fungus Rhizosphaera disease right now would be a Wright said another tree kalkhoffii. problem he has been seeing waste of money.

According to the University this summer involves another Affected trees should be of Minnesota Extension Serfungus called Anthracnose. sprayed in the spring when vice, the fungus attacks a new growth begins. A second Anthracnose attacks ash, oak, tree's needles starting from maple and other broadleaf application should be made the inner portions of the trees. two weeks to a month later. branches, then spreads upBut even with treatment, "This year has been particuward and outward. This trees need to be checked on larly bad," Wright said. "You leaves the tree with a hollow or barren appearance near its in future years to make sure see it on the leaves. It causes they haven't been re-infected. them to turn color and curl base. Occasionally, infection up. Often there is a prema"It's the susceptibility of this begins higher up in the tree particular tree," Wright said. ture loss of leaves."

Colorado blue spruce - Picea and spreads downward and "Even if there was no disease, Anthracnose can be here tooutward. pungens. Foreground is the day, gone tomorrow, accord"The Colorado Spruce is the the Colorado Blue Spruce blue form - background is wouldn't hold up as long as ing to Wright. He said this most susceptible," said Master the green form. area has experienced the Gardener Bob Wright of Bat- we would like them to.

They're not suitable to our problem for three years in a tle Lake. "The Black Hills area as we're just discoverrow.

Spruce is less susceptible." ing."

The good thing about AnWright said humidity has According to the extension thracnose is that the tree will something to do with the funGreen Ash trees: (Fraxinus gus activation, but the time of service, the first sign of infec- survive without treatment. pennsylvanica) tion occurs in late fall or in Left - defoliation by ash an- year also is a factor.

"No treatment is recomthe spring one year after inthracnose mended," Wright said. "It isn't "It just takes the right condifection. The second summer Right - unaffected. worthwhile. And really, after tions at the right time for the after infection, symptoms apyou see it, it's too late anyspores to settle pear as yellow needles which way." out on trees," later turn purplish-brown and Wright said.

If leaves are lost early, the drop from the tree.

"They're wind tree will re-leaf. Some trees A protective fungicide with borne, that's won't come back until the the active ingredient how they get next year. Treatment would chlorothalonil can prevent around." be recommended only when a new growth from becoming transplanted tree or small Wright said the infected. Rhizosphaera Needle stem has been infected two naturally occurCast may be controlled in one years in a row. ring fungus has year if fungicides are applied There's a fungus among us. It has been around for a long time. And slowly, it attacks spruce trees.

"The reason people think there's a big problem is apparently because more people are now aware of it," he said.

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Bug Plagues Widen State Ag Director Seeks Quarantine Reynoldsburg, Ohio Agriculture Director Fred Dailey today announced that Emerald Ash Borer (Agrilus planipennis), a destructive exotic pest from Asia, has been identified in ash trees in Hicksville in Defiance County, including at a wholesale landscape nursery and at a tool handle manufacturer. Dailey will seek an emergency quarantine to restrict ash trees, firewood, branches, and logs from movement off affected properties.

"We will work aggressively to prevent Emerald Ash Borer from taking hold in Ohio and elsewhere and causing damage like in Michigan," Dailey said. "I have initiated steps to quarantine the state and have asked for additional federal funding to accomplish this goal. The quarantine will allow us to regulate areas with known infestations in order to prevent further spread."

Ohio Department of Agriculture officials collected Emerald Ash Borer adults from trees on one property in Hicksville on August 7 after they received a call from a nursery owner indicating they suspected a problem. The sample was positively identified as Emerald Ash Borer on August 13.

Survey workers have identified borer damage on at least eight properties and will continue to look for affected properties in the area. Indiana officials are conducting a similar search across the state line just three miles west of

Hicksville.

The Emerald Ash Borer belongs to a group of insects known as metallic woodboring beetles. Adults are dark metallic green in color, 1/2 inch in length and 1/16 inch wide, and present only from mid May until early August.

Citizens can help by reporting signs of Emerald Ash Borer to the Ohio Department of Agriculture Division of Plant Industry at 800-2821955. They should also refrain from moving ash trees, lumber, or firewood inside or beyond the borders of Defiance County and alert the department at 800-282-1955 if they receive such items from Defiance County.

More information on detection and identification is available at the Ohio Department of Agriculture's web site at www.state.oh.us/agr.

been infested in the industrial area near Weston Rd. and Steeles Ave. W. The beetle is about 20 to 35 millimeters long with a glossy black finish with white dots on its back and two large antennae with banded white and black segments.

"It is like trying to find a needle in a haystack because the beetles spend most of their life inside trees," Ubbens said. The outbreak "is the first case in the history of Canada," he said.

Trees at risk include maple, elm, ash, poplar, alder, willow, and various fruit trees.

Ubbens said the beetle, which travels from China by burrowing into wood packaging, infested trees in Chicago in 1998, New York City in 1999, and New Jersey in 2000-01.

Ron Gordon, a director of solid waste collection for the North York area, said his ofWed, September fice has been instructed, not 17, 2003 to pick up yard waste from Beetle threatens maple, the 1,800 or so homes they elm, ash trees service until the infestation

By JACK BOLAND, TORONTO SUN has been isolated and the affected trees destroyed.

Hundreds of trees in an industrial area of North York "In all probability we are and nearby Vaughan have going to chip it. And that been infested by the Asian should destroy the larvae. long-horned beetle. The bee- (Trees and waste) will be tle has been positively identi- then put into compost sites fied by the Canadian Food and the heat should destroy Inspection Agency in broad- the remaining larvae," leaf trees in the area borGordon said. dered by Finch Ave., north to "We are going to lose Steeles Ave., and from Hwy. thousands of trees in the 400 west to the Humber north end of the City of ToRiver. ronto. I do not want to lose Richard Ubbens, of the City hundreds of thousands of of Toronto forestry office, trees," Mammoliti said. said hundreds of trees have

For information on the Emerald Ash Borer visit: http://www.na.fs.fed.us/ spfo/eab/

Emerald ash borer (Agrilus planipennis) Photo Courtesy of: http:// www.na.fs.fed.us/spfo/pubs/ pest_al/eab/eab.htm

For more information on the Asian long-horned beetle visit: http://www.na.fs.fed.us/ spfo/alb/

Asian long-horned beetle (Anoplophora glabripennis) Photo courtesy of: http:// www.na.fs.fed.us/spfo/ albpestalert/index.htm

Contact Phone Numbers Program Contacts:

TCAAG Members:

Paula Denman, Chair – 612-338-1871, pjdenman@mn.rr.com Bob Condon – 952-890-1228, bobnbunny@juno.com Gary Johnson – 612-625-3765 or grjonson@.umn.edu Laurie Drolson – 651-464-9829, ldrolson@yahoo.com Dave Hanson – 612-624-1226 or dlhanson@umn.edu Mailing Address: 115 Green Hall, 1530 Cleveland Ave. North, St. Paul, Bruce Granos – 952-423-5211, bjgbjgbjg@hotmail.com Mimi Hottinger – 507-388-4838, mimih@mctcnet.net MN 55108 Barb Kirkpatrick – 651-490-9816, sambucus@attbi.com

County Contacts: Anoka County (Patrick Weicherding) – 763-755-1280 or weich002@umn.edu Blue Earth – (507)389-8325 Carver County (Jackie Smith) - (952) 442-4496 or smith515@umn.edu Dakota County (Barb Stendahl) – 952-463-8002 or stend004@umn.edu Hennepin County (Bob Mugaas) – 612-374-8400 Olmstead County (Doug Courneya) – 507-285-8250 or courneya@umn.edu Ramsey County – (Doug Foulk) – 651-777-8156 Scott County (Jackie Smith) - (952) 492-5410 or smith515@umn.edu St. Louis County (Bob Olen) – 218-726-7512

Additional Reference Contacts: Debby Newman (Info-U) – 612-624-3263 Don Mueller, DNR Forestry – 651-772-6148 or don.mueller@dnr.state.mn.us Great River Greening – 651-665-9500 Ken Holman, DNR Forestry – 651-296-9110 or ken.holman@dnr.state.mn.us Rich Hauer, Minnesota Department of Agriculture (certified tree inspector workshop coordinator) 651-296-0592 or rich.hauer@state.mn.us Paul Walvatne MNDOT – 651-284-3793 or Paul.Walvatne@dot.state.mn.us Tree Trust – 651-644-5800

Leaves of Three Quiz Answers...

Photo 1) Harmless. This character is boxelder (Acer negundo). Young boxelder can easily be confused with poison ivy since it often has leaflets grouped in threes. Look for the white ”blush” on the green to purple stem and look for opposite branching.

Photo 2) Harmless to a certain extent. There are spines on the Rubus species (raspberries) and there are many wild varieties. Often they will be growing in and amongst poison ivy or vice versa. Most raspberries, besides the thorny stems have leaves with toothed margins and prominent veins.

Photo 3) Be careful here. Two are harmless, one is not. Poison ivy is the character on the right. Note the leaves of three with notched margins.

How about the other two - Center is a Rubus spp. and on the left is hog-peanut (Amphicarpa bracteata).

Photo 4) Looks like poison ivy - has a long trailing petiole like poison ivy. Leaf margins are notched and oppositely branched.

Again refer to photo 1 for a better picture of boxelder.

Photo 5) No trick here. This photo is the real thing. Toxicodendron radicans.

Parting shots: Left is the seed of Toxicodendron radicans. Right is the seed of Toxicodendron vernix.