Tree Care Advisor Newsletter

Inside This Issue:

“Kings Broad-arrow Tree” Dave Hanson

1

Quick Hits /

Volunteer Opps

2

White Pine Blister Rust

Barb Kirkpatrick

2

Putting Down Roots Cliff Johnson

3

Arboricultural Myth:

Ian McKiel

5

A Thank You!

Dave Hanson

7

Research: A top 10 list Gary Johnson

8

Contacts 12

Volume 10 Number 3 Dave Hanson and Gary Johnson, Managing Editors

http://

www.mntca.org

Summer time! Things are certainly happening in the world of trees - we have bugs, storms and fungi eating States. Yes, back in 1992 it was reported that the largest organism in the world was eating Michigan (an Armillaria fungus in the family Basidiomycetes) and Cliff is telling us about one of its other attributes, foxfire. Several record breakers showed up in 1992, first was the Armillaria bulbosa covering an estimated 15 hectares in Michigan, about 9.7 metric tons and estimated at 1500 yrs old, then an Armillaria ostoyae organism in Wash-ington State checked in at an estimated 600 hectares (6 square kilometers). But, hang on, along came an aspen clone (Populus tremuloides) in southern Utah with an estimated 47,000 individual stems covering 50 hectares and with an estimated weight of 5,000 metric tons above ground. I suppose I’ll have to go on the road to get pictures for a fu-ture issue,

Ok Gary?

“King’s Broad-arrow”

Dave Hanson

We’ve all heard of the American Revolution and some of the trigger events like that little Tea Party in the Boston Harbor. Con-spiracy theorists and specula-tors might wonder, “Was it all about tea and taxation?” They would be giddy to know that - there was more to the story; in fact a tree species had a part in stirring up the American pioneers against the British Royals.

North America was home to the finest pine tree the Europeans had ever laid eyes on and it was so plentiful that early explorers (timber hunters) referred to the ex-tensive stands as “veins”.

Unbelievable trees 150 to 240 feet tall and trunks free of branches to heights of 80 feet or more were plentiful. Almost all lumber species today pale in comparison.

Lumber from these trees was very light, yet extremely strong. The wood was very easy for a carpenter or wood worker to work with and due to its characteristics and slow growth it was very re-sistant to rot.

The early American pio-neers had this timber on their properties, within their grasp, yet they were not to touch it. All of the lands were “Crown Lands” and singled out on these lands was a species of pine marked

with the “Kings Broad-Arrow” as property of Brit-ain. One can understand why the early American pio-neers, shipbuilders and other craftsmen were more than a little irritated. Donald Peattie in his book A Natural History of Trees points out that “Swamp Law” was exer-cised by many of the pio-neers. Many fine pines were cut illegally, the “Kings Broad Arrow” mark was obliter-ated and the wood was put to use.

This species and its lum-ber truly shaped early Amer-ica. Houses, businesses, bridges and countless other structures and day-to-day utility items

The King's “Broad-arrow” Trees

Continued page 10

Page 2 Quick Hits

Got Storm Damage

While I was enjoying a wet week in the BWCAW, Gary and assorted others were

out collecting storm damage data and photos In the Richfield / Edina area. Some of

the photos and related information can be seen on the U of M Forestry Extension

web site at the address below:

( http://www.cnr.umn.edu/FR/extension/gotstormdamage.html )

Photos from the June 25th, 2003

storm event.

Barb Kirkpatrick

Ramsey County TCA

Have you ever wondered why one pine flourishes in the midst of a stand of dis-eased pines of the same spe-cies? Does the pine that es-caped disease have an ‘inherited’ genetic resistance or are there other reasons it seems unaffected? Dr. Robert Blanchette, Univer-sity of MN, Department of Plant Pathology, is conduct-ing research into this phe-nomenon. Specifically, what makes some eastern white pines more resistant than others to infection by the fungus Cronartium ribicola?

Cronartium ribicola is the causal agent of white pine blister rust (WPBR) This causal agent originated in

Asia, subsequently estab-lished itself in Europe in the 18th century, and then was introduced to North Amer-ica circa 1906. It is believed that the fungus first arrived in New York from Germany on nursery grown white pine seedlings. This is the strain of C. ribicola that exists in Minnesota today. A second strain of C. ribicola was intro-duced to Vancouver Island, British Columbia around 1920. During the early 1900’s white pine was exten-sively logged as a premium timber species. By the 1950s WPBR had spread to most of the commercial white pine regions in North America. Recently a third strain of C. ribicola has been identified in the Southeastern United

States.

To best manage a disease, one must understand it’s life cycle. WPBR is a fungal dis-ease with a rather compli-cated life cycle. This disease cannot spread from pine to pine, but rather requires an alternate host (Ribes spp.) to complete the disease cycle. There are 5 spore stages to WPBR: two (pycniospores and aeciospores) occur on pine, and the remaining three (urediospores, teliospores, and basidiospores) occur on the alternate hosts, currant and gooseberry (Ribes spp.) bushes. For many years it was thought that eradicating the cultivated European black currant (Ribes nigrum) would eliminate this disease. After

Research Update: Management of White Pine Blister Rust

Branch flagging and dieback

associated with white pine

blister rust.

Yellow aeciospores (fruiting

bodies) on bark of white pine. Continued on page 11

Page 3

Cliff Johnson

Carver County TCA

Carver and Scott County

Master Gardener

Research uncovers answer

to stumps that glow in the

dark

The question was one

of the more unusual I’ve

been asked in 11 years of

fielding horticultural phone

calls: “Can you explain

why the stumps in my

backyard glow at night

when I walk out to put a

trash bag in the garbage?”

My first impulse was to

ask whether the caller had

been hitting the gin a little

too heavily before bed-

time.

Fortunately, I went

with my second impulse,

which was to explain that I

couldn’t explain the phe-

nomenon but I would find

out and call him back.

A little internet search-

ing led to a fascinating dis-

cussion of -- and you

may know it by any one of

these names -- biolumines-

cence, foxfire, will-o’-the-

wisp, faerie fire or honey

fungus.

Each of the names re-

fers to a soft glow or light

coming from leaf-covered

ground or dead wood. Lu-

minous wood, most com-

monly called foxfire, has

been known for centuries

among people living near

forests. Foxfire is a curios-

ity, an educational toy for

children, and part of folk

tales and cultural myths

concerning elves, ghosts,

and supernatural “cold”

fires. Mark Twain makes

reference to it in Adven-

tures of Huckleberry Finn.

What causes a stump

to glow in the dark? Is it

fungal, algal or extraterres-

trial?

Despite all the ro-

mance and myth sur-

rounding foxfire, its

source is fungi rotting

wood, explains Kim

Coder, a forestry profes-

sor at the University of

Georgia. The most com-

mon luminous fungi in a

forest is a tree root rot

and wood decayer. The

glow of foxfire comes

from rapidly growing and

healthy fungal cells

(rhizomorphs) consuming

wood.

Around 40 species of

fungi and certain bacteria

are capable of carrying out

chemical reactions that

give out light, sometimes

causing the wood or

leaves they attack to be-

come luminous. One of

the most common species

growing on rotten stumps

capable of luminescence is

honey fungus (Armillaria

mellea).

The technical name for

foxfire is bioluminescence

-- the emission of light

from living things (i.e., fun-

gus). Bioluminescence is

produced by the sudden

decay of a high-energy

molecule to a lower en-

ergy form. One way to

understand biolumines-

cence, Codor says, is by

comparison to photosyn-

thesis. Bioluminescence is

the reverse of photosyn-

thesis. In photosynthesis, a

living organism captures

light and carbon dioxide to

make organic materials

Putting Down Roots

Douglas fir trunk rotting on the

forest floor

Rhizomorphs or shoe strings of

armillaria species. Look under

the bark of dead and dying trees

and you may find these struc-

tures.

Page 4

and release oxygen. In bio-

luminescence, light and

carbon dioxide are re-

leased by breaking apart

organic materials using

oxygen.

Nature provides in-

stances of biolumines-

cence in other creatures,

including bacteria, animals,

fish and insects, including

fireflies. Some mystery re-

mains attached to foxfire,

however, since research-

ers are unable to ascertain

any survival advantage for

fungi emitting this strange

glow.

I found an interesting

website (http://

www.stumps.biz/

honeyfungus.htm) for a

stump-removal company

in northern England. A

page of their website is

devoted to honey fungus

and offers the following

facts:

1. Aristotle noted honey fungus 2000 years ago.

2. In medieval times people lit hay barns with clus-ters of rhizomorphs, and roots covered with rhi-zomorphs were consid-ered to have medical power. These were the

original magic wands.

3. Soldiers in WWI put pieces of decaying wood on their helmets; the glow helped them avoid comrades in nighttime trenches.

4. In WWII fire wardens covered timber stacks to prevent enemy aircraft spotting them.

Honey fungus is the

woodlands’ hyenas, jackals

and vultures rolled into

one. It is a scavenger. It

cleans up woodland

whether it wants it or not.

It reduces the lignum and

cellulose to glucose, which

insects can digest. With-

out honey fungus the sur-

face of the world would be

piled high with the corpses

of dead trees.

The greatest interest in

foxfire and honey fungus

appears to be in the UK. I

even discovered a website

by an organization called

the North West Fungus

Group. NWFG was estab-

lished in 1994 as a regional

umbrella group to pro-

mote an interest in fungi in

the Northwest of England

and Wales, UK. What do

you suppose a typical

NWFG monthly meeting

consists of?

Setting out to see fox-

fire can be difficult, espe-

cially where there is light

pollution. Coder says that

foxfire is a very low-

energy light. He suggests

picking overcast or

moonless nights without

surrounding artificial lights.

Your eyes will need to be

fully dark-adjusted for 20-

30 minutes. Leave flash-

lights off and get away

from any other types of

light reflectance other

than starlight. Forget flash-

lights, fires, candles, watch

lights, or other light

sources. Passive photo-

multiplier binoculars (night

scopes) can be helpful. Fi-

nally, Coder suggests, be-

ware the other denizens

of the nighttime forest.

Given all the interest in

foxfire, perhaps I should

suggest to the Scott

County caller that he

charge admission for

guided tours of his lumi-

nescent backyard stumps.

Honey mushrooms - the fruiting

structure of Armillaria species.

The mushrooms appear in late

summer or early autumn con-

firming the presence of armil-

laria.

All photos for this article cour-

tesy of the Unite States Depart-

ment of Agriculture, Forest

Service.

Source: Forest Insect and Dis-

ease Leaflet number 78,

Armillaria Root Disease.

Page 5 Arboricultural Myth:Tree Fertilization Will Fix any Malady

Ian McKiel, Horticulture Student, University of Minnesota

Most people think of tree fertilization as food for trees. It provides nu-trients the plant needs for fast growth, greener leaves, and a longer life span. Putting a tree on a regular diet of nitrogen and other essential nutri-ents is equated to making sure a child gets healthy meals. Whether or not this is the case, it does seem to be the public per-ception. So, why is it then that at the first sign of a problem, a wilted leaf or dead branch, the immedi-ate response is to fertilize? Would it make sense to give a child with a broken arm a cupcake and expect everything to be fine?

This perception of fertilizer as a catchall rem-edy for trees is wide-spread, and the green in-dustry does little to change it. Many media gardening “experts” have been heard to say that the first thing to be done when there is any sign of a plant problem is to blanket on the fertilizer. Even a

published paper on trees from the University of Wisconsin Extension states, “If leaves are light green or yellow-green, you’ll need to fertilize. Fertilizer is probably also needed if trees and shrubs show short annual twig growth, excessive dead wood, or sparse foli-age.”(Hasselkus) When reliable sources swear by it, how can this practice be wrong?

Unfortunately, it is. A tree is a system in which nutrients provided by fer-tilizer are only a part of the total function. Chlo-rosis or yellowing of the leaves, heavy dieback, and stunted growth are all signs of a tree going through stress. To fertil-ize in response to symp-toms like these is not only ignoring the actual cause of the stress, but also has the potential to add stress to the tree.

There are many factors that can cause stress to a tree, and many different visible symptoms to that stress. Putting aside the fact that what is the “normal” appearance

of any given species is highly variable, there are several common abnormal traits that indicate stress. Chlorosis, or yellowing of the leaves, can signify a lack of nutrients, as can stunted annual growth or dieback in the canopy. However, assuming fertili-zation is the remedy to any of these symptoms without further investiga-tion risks not only the tree’s further decline, but the possibility of accelerat-ing the process. Consider for example, a Littleleaf Linden (Tilia cordata) planted in a boulevard showing significantly re-duced stem growth over the past two years, and some dead branches within the canopy. An ap-plication of a general fertil-izer could be detrimental once it was discovered that a new sidewalk and curbs were constructed shortly before the tree began showing signs of stress. “Fertilizer, espe-cially nitrogen, causes the tree to grow more leaves faster. The energy that should be used for defense is redirected to growth.

Quercus alba leaf pair - Leaf on

the left has definite inter-veinal

chlorosis. Will Fertilizer help?

Not likely - This tree is the

source of the leaves above. The

chlorosis is not consistent

throughout the tree. There is

more going on here than a nutri-

ent issue.

Pinus strobus: White Pine

- Twisted needles.

- Off color?

Is this herbicide damage?

Is this a nutrient deficiency?

Not at all - remember the num-

ber one diagnostic rule:

- Properly identify the host and

its characteristics!

Host is: Pinus strobus ‘Contorta’

Page 6 Fertilizer continued

An overfertilized tree may be susceptible to disease and is in danger of using up all of its remaining en-ergy reserves” (Van Ells). In this case, fertilization may now put the tree un-der greater stress, and could lead it downward in the spiral to becoming strained, and subsequently firewood.

In the above exam-ple, visual inspection of the tree was the method of determining that fertilizer was needed, and that is a good first step. However, once a nutrient deficiency is suspected, it is impera-tive to do a soil test. This will show the concentra-tion of micro (required in small amounts) and macro (required in larger amounts) nutrients. Most Minnesota soils have a suf-ficient amount of micronu-trients and nitrogen will be the limiting nutrient (generally soils have enough potassium and phosphorous to support most plants). The micro-nutrient most commonly lacking in Minnesota soils is iron, which results in iron chlorosis (Gillman).

Soil tests will also show the pH of a sample. pH refers to how acidic or alkaline the soil is. On a scale of 1 being the most acidic and 12 being the most alkaline, soils can range typically anywhere from 3.3 to 8.5. Different tree species tolerate dif-ferent pH levels. If the pH of the soil is outside the range that a tree will tol-erate, the root system is prevented from function-ing normally. The ions that cause pH to be either acidic or alkaline can tie up nutrients, thus preventing the roots from taking up those nutrients even if they are present in suffi-cient quantities in the soil. Therefore, piling on even greater amounts of nutri-ents that the tree is unable to access is obviously a waste of money, time and effort in this situation.

Once a soil test has determined specific nutrients are absent, fer-tilization is an effective way to give the tree the support it needs to grow. With trees, as in most cases, it’s better to investi-gate a little further than a

little later.

For More Information on the Value of Fertilizing Trees:

http://www3.extension.umn.edu/distribution/horticulture/DG7410.html#deter

http://www1.uwex.edu/ces/pubs/pdf/A2308.PDF

http://www.wnrmag.com/supps/2002/oct02/ouch.htm

http://www.agctr.lsu.edu/enr/urban_shade/fertilization.asp

Note: Hasselkus wasn’t misquoted, but in the paragraph preceding the quote he does talk about soil tests. I believe it’s more a case of bad writing than anything else, but a layman wouldn’t know that and might take the information at face value.

Information from a reliable

source - these lindens are ap-

proximately the same age. Note

the obvious disparity in height,

dbh, and crown. One could

surmise that fertilizer is re-

quired - the real problem oc-

curred at planting time. This is a

planting depth problem.

Leaves of a Pin Oak exhibiting

chlorosis - this is typically a high

pH problem and there are

remedies, but it is not a one

time solution.

Page 7 A Campus Field Day

We had fun! This is a public thank you to several TCA laborers. On June 18th the following people took part in harvesting 120 trees from the TRE nursery planting depth study on the U of M Saint Paul Campus.

To make the list complete we also had Patrick Weicherding and Katie Frerker lend-ing a hand. With this large group the work went fairly quickly. Many of the removals were completed with an air knife, while some were shoveled out of the ground. The trees were then placed in a tank of water until data and photos could be gathered on each individual. Results are promising, yet are still being finalized. Thanks! I apologize to those that may not have been contacted. Due to short notice and tight schedules - E-mail was used to get in touch with people.

Joe Baltrukonis Bruce Nelson

Renae Chesley Gail Soens

Bret Hubert and son Tyler Kim Sullivan

Annette LeDuc Sara Tinetti

Stem

Future SGR

Photos from the field:

Look to the arrows for some fine

Future SGR examples on lindens

Gary and the air knife

“Just demonstrate it one more

time, please.”

This group probably wasn’t

learning as slowly as they made

Gary believe. Gary had been

duped!

At left:

The swim tank

and data collec-

tion area.

There are actually several

potential SGRs in this

photo.

There are actually several

potential SGRs in this

photo.

Page 8 Research - A Top 10 List

An Update on Stem Girdling Roots and Planting Depth Research, or

"No, that's not what I said!"

by Gary R. Johnson

It's been awhile since I've chatted with you about the ongoing work at the University regarding tree health and depth of soil over roots. Many of you went through the TCA core course training several years ago when we were just beginning our research. And for many of those people, regular atten-dance at update sessions and conferences has kept to pretty much up-to-date on the status of our work and recommendations. However, not everyone has the opportunity to attend update sessions, so I thought that I would take the time to fill you in and maybe dispel some rumors.

Rumor number one: Gary is doing all of this research. False. Gary is part of a great team that keeps expanding. Currently, the core research team includes Patrick Weicherding (Extension urban forester), Dave Hanson, Chad Giblin (TRE research nursery manager), and Jeff Gillman (Department of Horticulture). Quite often we are joined by others when we do work in areas off-campus: Doug Courneya (Olmsted County Extension Horticulturist), Rich Hauer (MN Dept. of Agriculture) and many TCAs who have devoted many volunteer hours at the research nursery. I don't want to slight any of the TCAs who have helped, but I want to particularly applaud the help that Bruce Nelson has contributed on a weekly basis at the nursery. And finally, Mike Haugen, grounds manager for part of the St. Paul campus, who has helped us so many times by providing the Air Knife that has made our lives more bearable during root collar examinations and harvesting trees.

Now maybe you'll understand why I look bothered when people refer to this as "Gary's research."

Rumor number two: Everyone knows about this problem now and contractors or growers can be sued if they plant trees too deep or harvest/grow trees with too much soil over the roots. This kind of relates to an associated rumor: Minnesota now has standards that require all tree roots to be within one inch of the soil surface. Both are false.

First of all, not everyone knows about our research work, so we have a lot more work to do espe-cially regarding getting the word out. Most people still believe that "deeper is better," unfortunately. And many growers and contractors have not received the information or are resisting the new infor-mation. Passing on the information to both audiences require the same approach: do it respectfully, with an open mind, and not in a confrontational manner. No one will be receptive to this research if it's stuffed down their throats. They WILL choke on it, and spit it out! Our challenge is to present it to them in a manner that they will see the benefits to their landscapes and their pocket books.

Minnesota HAS NOT developed any standards regarding the maximum amount of soil allowable over root systems. There are several municipalities and agencies that have developed their own standards or specifications, but they are unique to those entities. For instance, MnDOT will only accept trees/shrubs with less than 4 inches of soil over the root systems. Then, when those trees and shrubs are planted, enough topsoil and roots must be removed so that the first true branch roots are within an inch of the soil surface. Other communities such as Minneapolis and St. Paul also have specifications, some more strict, some more liberal.

Therefore, in the absence of standards, growers and contractors can't be sued or denied payment…unless they don't adhere to the specifications of those particular agencies or municipalities contract-ing the materials or services. So, does that leave the average person totally helpless? Nope. Draw up your own specifications for accepting plant materials or landscape installations. Then, the provid-ers know what to expect and have the choice to provide you with plant materials or services based on the specifications in your contract. You do it when you buy a new car or house, don't you? Do it

Mike Haugen: Demonstrating

root excavations with the air

knife on elms in the TRE nurs-

ery.

Planting specifications diagram

showing trunk flare, stakes,

watering and backfilling.

MnDOT has an extensive

specifications booklet which is

often referred to by municipali-

ties. Once the specs are in

place - then policing begins.

Diagram courtesy of USFS.

Research - A Top 10 List Page 9

with plants or installation services, too.

Rumor number three: Pot-bound trees will end up with stem girdling roots. Not if the stem isn't buried in the container soil! Oh, I suppose it COULD happen. I've seen plenty of trees with stem girdling roots above ground. However, we still don't know if tissues in the flare area of a tree react the same as pure stem tissues. There is a possibility that roots can graft to flare tissues, with little to no harm.

Encircling roots become problematic when they come into conflict with buried stems. If that stem is buried 6-10 inches below ground and there are encircling roots within a few inches of the stem, I can almost guarantee you that stem girdling roots will develop.

Rumor number four: Growers, retailers and landscape companies know they are selling/planting trees that will be short-lived, which just gets them more business in the future. Oh, come on! There may be some like that out there, just as there are unscrupulous politicians, doctors, dentists, mechanics and teachers. But I honestly believe from my experience that they represent a small mi-nority. Most are just ignorant of the problem and research.

Rumor number five: If we get growers, retailers and installers to fall in line with best practices for growing and planting trees, our problems with stem girdling roots will be over. False; not as long as people keep over-mulching trees. Plus, most trees and shrubs are still planted by homeown-ers who still believe in "deeper is better."

Rumor number six: All trees with stem girdling roots will die. Well actually, they will die, but not necessarily from stem girdling roots or planting depth problems. Some actually live with SGRs deeply imbedded in the trunks for many years and look just fine. But it's just like any other stress on a living organism, and SGRs affect some trees more severely and quickly than others.

The problem with doing research is that all recommendations are based on probability: what is the likelihood of failure when you plant 1000 trees too deep? Well, if they're littleleaf lindens, over 90% will eventually have problems with stem girdling roots, and if a straight-line windstorm rips through the area, expect about 3/4 of them to snap off at compression points from SGRs. However, you cannot walk up to one tree and say "this is the tree that will have problems and fail in a windstorm." When you work with your clients, that is what they are asking you, and you can only give them probability information, not specific to that one tree in their yard.

What we have found: trees with 50% or more of their stem circumference compressed by SGRs will decline in health and condition faster, will be short-lived, and are more likely to fail in wind-storms…but it depends! (don't you hate that word?) Are all other growing conditions ideal? How big is the tree? Is it 10 feet tall or 70 feet tall? Is it in a wind-protected area, or is it facing the full force of winds in a new subdivision? Is there decay associated with the compression or elsewhere in the tree? Is it a dense tree, like a spruce, or more open, like a honeylocust? SGRs are part of the diagnosis and predictive process.

Rumor number seven: All trees planted too deep will get stem girdling roots. Nope, but de-pending on the species and size of the tree planted, a significant number will develop them. Then, their health and condition can be affected as in rumor number six.

Rumor number eight: Stem girdling roots are the biggest problems associated with planting too deep. They are definitely a huge problem, but a bigger problem is simply the lack of soil oxygen and moisture that deep planted roots have at their disposal. The deeper you entomb roots (regardless of soil type), the less oxygen and moisture is available to a plant, most critical is the oxygen. Way too many trees and shrubs die long before they can develop SGRs simply

Continued Page 12

Planting Depth Study: F24 A sugar maple planted with first

order roots at 10 inches. No

SGRs after 3 years, but some

adventitious roots (see arrows).

Commercial site: Overmulch-

ing commonly referred to as

“the mulch volcano”

Note the pop can (arrow) - it

is dwarfed by the mulch pile.

Page 10 King's “Broad-arrow” (from page1)

were built from the wood of Eastern white pine (Pinus stro-bus L.). However, the popu-larity of white pine brought with it a very high cost. East-ern white pine was exten-sively harvested during the 1800’s on into the early 1900’s leaving very few “virgin” old growth stands today. Eastern white pine has made a remarkable re-covery and an indication of white pines reproductive ca-pability shows in another common name used around some Northeastern States, “old field pine.”

As farming left the Eastern States in the 1860’s for the Midwestern prairies, white pine was able to re-inhabit the abandoned fields and to-day there are once again nearly pure stands of eastern white pine.

One of the whispering pines of the north woods, Eastern white pine has 5 soft needles per fascicle or bun-dle. The needles are roughly 2.5 to 5 inches long, dark bluish green in color, soft and very flexible. The needles tend to persist until the end of the second season or the spring following that.

The 3 to 5 inch cones of eastern white pine are small in comparison to its cousins out west. Western white pine (Pinus monticola) cones can be up to 10 inches while those of sugar pine (Pinus lambertiana) can be up to 20 inches in length.

Around Minnesota white

pine is found on a variety of sites, but develops best on the well drained, moist, sandy loams of ridges. As the tree matures and begins to gain advantage over neighboring trees the top begins to spread with the branches reaching distinctively upward much like the horns of a stag. This trait makes white pine fairly easy to distinguish along Northern Minnesota’s skyline and even within the confines of the Metropolitan area.

While the bark of a young white pine is quite smooth and has a greenish tint, with age the bark of white pine becomes quite dark and fur-rowed or ridged. The bark is not as fire resistant as some of its cohorts such as red pine. For this reason white pine is often found within the mosaic of the forest on the east side of lakes, streams and ridges protected from the fires driven by westerly winds.

The cool shade of a pine grove, the pine scent and the whisper of the wind through the boughs have long made pine stands of the north woods a pleasing site to visit. The experience touches hu-man emotions so strongly that pines are often a choice for urban landscapes. Unfor-tunately, the white pine is not always the perfect or even the best choice for urban environments. It grows here, don’t get me wrong. It can grow to be quite large but the Twin Cities are a little

hot and dry, being along the western edge of the white pines range. With this in mind, realize that white pine will require a consistent moisture regime (mulch) and young trees require protec-tion from harsh drying condi-tions (wind and sun) of win-ter and summer. Road salt in the form of salt spray is an-other damaging agent preva-lent around the State of Min-nesota. Proximity of a land-scape site to a road should always be considered when choosing white pine as it is quite susceptible to salt dam-age.

Now, I refer you to two other sources: First, in this issue look to Barb Kirkpatrick’s companion arti-cle on white pine blister rust. This disease must be consid-ered when white pine is on the list to be planted on a site. Second, refer back to Mike Zin’s article titled “Pines”, Tree Care Advisor Newsletter, vol 9, number 1, pages 18-21 (January 2002, available on the web).

So, the next time you hug your white pine, maybe not, or you are standing in a grove of whispering white pine think about the early pioneers and their disdain for the “King’s Broad-arrow” emblazoned on the white pine on their property. In reality the Revolutionary War was about many things and believe it or not the East-ern white pine weighed heavy in the decision to go to war.

Eastern white pine cones

Note the rougher bark at the

base of the tree

Eastern white pine branch tip

5 needles per fascicle on an

eastern white pine

Note the smooth bark in the

picture

Page 11 King's “Broad-arrow”

Works Cited:

Peattie, Donald C., A Natural History of Trees of Eastern and Central North America. Houghton Mifflin Company, Boston MA, 1991

implementing an extensive eradication program in the white pine regions of the United States, it was realized that wild Ribes also serve as an alternate host to WPBR. Thus a new strategy for man-agement of this disease was developed that focused on selecting and improving blis-ter rust-resistant white pines.

For decades, it has been noted that wild white pines exist that appear to be resis-tant to blister rust. If the mechanism(s) by which a re-sistant tree protects itself from infection could be iden-tified, we may then be one step closer to being able to screen and grow blister rust-resistant eastern white pine. This is where Dr. Blanchette’s research comes into play. He has artificially inoculated different strains of white pine with C. ribicola and studied the plants responses at a microscopic level.

What Dr. Blanchette and his graduate students have found is that some white pine families tested reacted differ-ently in his study to infection by C. ribicola. Normally the fungus initially infects needles and then moves into the

branch, and then into the main stem where it attacks the food and nutrient con-ducting tissues of the tree. This results in cankering which gradually kills the tree.

One seed source of inocu-lated seedlings exhibited a ‘hypersensitive-like’ response where death of cells adjacent to the infection site oc-curred. Keep in mind that C. ribicola is an obligate parasite that needs live host cells to stay alive. The death of host cells surrounding the infec-tion effectively restricted the fungus, as its colonization could not continue without live host cells. Additionally, when non-infected seedlings from this resistant family were examined under the electron microscope a greater portion of their nee-dle stomata were plugged with wax when compared to infected seedlings’ stomata from the same strain. This seems to be significant be-cause C. ribicola initially in-fects pine by penetrating the needle stomata with its hy-phae. It is thought that this wax covering the stomata may play a role in preventing the fungus from penetrating

into the needles. So there appears to be two mecha-nisms of defense at work in this first white pine seed source: cell death adjacent to the infection, and wax cov-ered stomata.

Two other families of seedlings responded differ-ently to inoculation by exhib-iting a concentration of phe-nolic compounds near the site of infection. These phe-nolic compounds appear to restrict hyphal growth as these seedlings also exhibited some degree of resistance to infection.

To date, Dr. Blanchette’s research has shown some intriguing results. Primarily, there seems to be more than one way white pine respond to and resist infection by the fungus C. ribicola. Further-more, these responses ap-pear to be genetic in nature. If research can unlock the ‘genetic code’ that makes white pine rust-resistant, per-haps some day eastern white pine will once again flourish in massive numbers.

White pine seedling trials.

Seedlings inoculated with

Cronartium ribicola .

Ribes spp. growing in a green

house for use in the white pine

blister rust trials.

The alternate host for C. ribi-

cola

Photos for Barb’s article cour-

tesy of Doctor Robert

Blanchette, University of Min-

nesota, Professor in the De-

partment of Plant Pathology.

White Pine Blister Rust (continued from page 2)

because their roots are too deep and the root systems wither away. No soil oxygen, no root growth. Poor soil oxygen, poor root growth. Poor root growth, unhealthy plants above ground. Unhealthy plants above ground, plants that are more vulner-able to common insect problems, diseases and other environmental stresses.

Our research has shown that at least with bicolor oak, green ash, littleleaf linden and sugar maple, deep planting (regardless of the presence of SGRs) leads to declines in health and condition above ground. Someday with more research, we'll know more about other species, but I have no reason to believe that most others will be dramatically different from these species.

Rumor number nine: Stem adventitious roots are bad roots. False, if they are growing away from the stem. Only those that are growing back or around the stem can develop into girdlers and potentially harm the tree. So, if they're growing away from the stem, they're doing no harm.

Rumor number ten: Tall or bare-rooted or grafted trees MUST be buried deeply, otherwise they will lean too much or windthrow during storms, or die from cold winters. False. Our research conducted in 2002 revealed that there is no advan-tage to deep planting in regards to stability. Other research conducted on grafted fruit trees in the early to mid-1980's had the same conclusions. If it's real windy and the trees are poorly rooted, you'll probably need to straighten them regularly or give them some temporary staking…regardless of planting depth. And burying the graft union adds no extra winter hardiness pro-tection. As a matter of fact, it weakens the trees' long term health.

Sooooo many rumors, so little time. I hope this clears up some of the misunderstanding surrounding our work, what we feel we have learned, and all that we feel we still need to learn. This research is in its infancy, relatively speaking, but we're plugging away and added three new research projects to our plate this year. Little by little we're learning more and hopefully helping you as TCAs to better help your clients (and keep your own trees alive!). Stay tuned for more.

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 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 cour-neya@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

TCAAG Members: Paula Denman, Chair – 612-338-1871, pjdenman@mn.rr.com Bob Condon – 952-890-1228, bobnbunny@juno.com Laurie Drolson – 651-464-9829, ldrolson@yahoo.com Bruce Granos – 952-423-5211, bjgbjgbjg@hotmail.com Mimi Hottinger – 507-388-4838, mimih@mctcnet.net Barb Kirkpatrick – 651-490-9816, sambucus@attbi.com 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

Research - A Top 10 List (From page 9)

Below is a link from Ken Holman - Minnesota DNR.

The .pdf brochure Experts Agree Don't Top Your Tree info is from the Missouri Community Forestry Council.

http://www.mocommunitytrees.com/images/MOBroch2002.pdf