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2007 Forest Health Highlight Page 1 

2007 Michigan Forest Health Highlights

Inside This Issue............ 

Resource Overview – Drought - Annosum Root Rot - Ash Yellows Project - Beech Bark 

Disease – Beech Management Guidelines - Emerald Ash Borer – Ash Management 

Guidelines - EDRR Update - Gypsy Moth - Hemlock Looper - Hemlock Woolly Adelgid - 

Invasive Plant Report - Jack Pine Budworm- Oak Wilt – Red Headed Pine Sawfly – Spruce 

budworm – Sirex Noctilio Wood Wasp – White Pine Problems 

Resource Overview Forests comprise 53% of the land area of the state, or about 19.3 

million acres. These forests are a critical component of Michigan’s environment and 

economy for the recreational opportunities and the products they provide. Forestry 

related industries and manufacturing employ 150,000 people statewide and annually 

contribute $9 billion to the state’s economy. Additionally, forest-based tourism and 

recreation support 50,000 jobs and add $3 billion to Michigan’s economy. Michigan’s 

forests contribute to clean air and water and reduce soil erosion.
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FFFEEEAAATTTUUURRREEEAAARRRTTTIIICCCLLLEEE

Drought continues to affect the health of Michigan’s forests. Many already drought 

stricken areas received only a fraction of normal precipitation in 2007. Precipitation totals 

across the state as estimated by National Weather Service radar are shown on the map 

below. The areas of greatest precipitation deficits were southwestern and eastern Lower 

Michigan and the western Upper Peninsula, where rainfall totals remained less than 25 

percent of normal. In some areas of the state, the month of July was one of the five driest 

on record. 

The Palmer Drought Severity Index depicts areas of long term precipitation surpluses and 

deficits. This index as of August 4, 2007 placed the entire U.P. and many areas of Lower 

Michigan in “Severe” and “Extreme” drought categories. 
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The effects of the drought are long-lasting. It takes years for trees to rebuild food reserves. 

The drought has been a major influence causing declines in susceptible tree species, 

especially when growing on dry sites with light, sandy soils or on lowland sites with 

significant water table fluctuations. Declining trees are susceptible to a host of secondary 

pests from defoliators to wood boring insects to root rot fungi. As a result, increases in tree 

mortality in oak from the two-lined chestnut borer (Agrilus bilineatus); in paper birch from 

the bronze birch borer (Agrilus anxius); in larch from the eastern larch beetle 

(Dendroctonus simplex), and in jack and red pine saplings from Diplodia and Armillaria 

were more common in 2007. Defoliators such as the gypsy moth, linden looper, fall 

cankerworm, jack pine budworm and spruce budworm were also epidemic as 

mentioned in other sections of this report. 

Percent of normal precipitation between June 2 and July 31, 2007 

Precipitation values are based on National Weather Service Stage III precipitation 

estimates (courtesy of the National Oceanic and Atmospheric Administration). 
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Annosum root rot (Heterobasidion annosum), a serious disease of red pine in the eastern 

United States, occurs in Michigan but has never been detected north of Lansing in the 

south-central Lower Peninsula. Root decay from this disease often kills infected conifers; 

infected trees that survive grow more slowly 

and are susceptible to windthrow and bark 

beetle attack. 

Surveys conducted in Wisconsin in 2006 

detected the disease in red pine stands at 

latitudes found in the Northcentral Lower 

Peninsula. The Michigan Forest Health 

Monitoring Program has stepped up 

detection efforts in northern Michigan to 

determine whether Annosum root rot is present. Recently harvested stands are at 

particular risk since fresh stumps provide an entry route for the fungus. Once established, 

the disease spreads to adjacent trees through root contact. 

Symptoms are similar to those exhibited by bark beetle-infested stands: pockets of dead 

trees, top-down dieback and thin crowns. Conks (mushrooms) and pocket rot on 

decaying stumps and roots can occur, but can be difficult to identify in the field. Also, 

bark beetles are often attracted to trees stressed by Annosum root rot and can make 

diagnosis of the primary cause of decline difficult. 

More information is available at: 

http://na.fs.fed.us/spfo/pubs/fidls/annosus/fidl-ann.htm 

If you come across conifer stands exhibiting symptoms similar to those described above, 

please contact your MDNR forest health specialist. 
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Ash yellows continues to be implicated in ash decline occurring around Michigan. FIA 

estimates place the total number of ash trees in Michigan at nearly 800,000,000. Data 

from the Rural Ash Monitoring Plot System (RAMPS), an FHM off-plot monitoring network 

established in 2004, indicates that white, green and black ash trees continue to decline 

across a variety of moisture and soil regimes within the monitoring gradients 

Ash trees under stress from ash yellows and ash decline are highly susceptible to attack by 

emerald ash borer, Agrilus planipennis. Identification of high-risk stands is a critical step in 

rapid early detection of EAB populations, and in employing silvicultural measures to 

reduce stand susceptibility and mortality. 

In cooperation with MDNR, Michigan State University began a project to assess decline 

and contributing diseases in white ash stands in Michigan. Objectives of the study are to: 

• Determine the distribution and severity of ash yellows, root and butt rots in urban, rural 

and forest ash trees across Michigan.

• Determine the frequency of occurrence of these diseases in forest stands with ash 

decline.

• Identify risk factors associated with these diseases in forested stands, including stand 

dynamics, climatic, physiographic and edaphic site factors and stand management 

history.

• Evaluate impact of these diseases on radial growth of ash.

• Quantify relationship between ash decline, ash yellows and various field symptoms, 

including deliquescent branching, witches’-brooms, basal bark cracks and epicormic 

sprouts.

• Assess role of insect vectors in establishment of ash yellows in forested stands.

Information from this study will also be used to improve the ash decline component of the 

national risk map model. 
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Beech Bark Disease 

The MDNR, in cooperation with Michigan State University, University of Michigan and 

Michigan Technological University, continue to monitor the movement of beech scale 

and the development and impacts of Beech Bark Disease (BBD). The BBD advancing 

front (e.g. areas infested with scale before fungal infection) has spread as far west as 

Munising in the U.P. and to Emmet and Charlevoix counties in the Northern Lower 

Peninsula (NLP) (See map). Isolated, satellite scale populations well ahead of the 

advancing front in both the Western U.P. and NLP 

are being studied by MSU to better understand 

scale spread rates to new areas, and colonization 

rates within stands after arrival. 

Management plans for beech containing stands 

anywhere in Michigan should now consider BBD 

vulnerability. Guidelines to manage American 

beech both within and ahead of BBD affected 

areas have been developed. Management 

strategies are influenced by the abundance and 

size of beech trees, and distance from the BBD 

advancing front. The goal is twofold: 1) To reduce 

BBD impacts ahead of the BBD killing front by decreasing the beech component such 

that a fully stocked stand remains to sustain production of both commodity and noncommodity forest resource values, and 2) To increase tree species diversity, thereby 

decreasing stand susceptibility and vulnerability to BBD and other new pests which target 

a single tree species or genera. These guidelines retain a beech component even in 

heavily BBD impacted areas. Keeping a minor beech component minimally affects 

sustained forest productivity and offers an extended period of mast production. Heavily 

scale infested trees are considered hazard trees in recreation and other high use areas. 

Created by Daniel Wieferich, MSU 

2007 

 Beech 

Scale Areas 
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Once infected, these trees will break off or “snap” unexpectedly. Scale infested beech 

are therefore removed if they pose a threat to human safety. 

The USDA Forest Service Research Facility in Delaware, Ohio continues to 

collect scions from Michigan’s resistant trees to study Beech Bark Disease 

Resistance. These trees resist scale establishment. Without the scale, 

beech trees are not susceptible to infection by Nectria species which 

cause beech bark disease. Scions from resistant American beech have 

been collected from infested areas of both the U.P. and LP. Michigan 

has agreed to develop and maintain 1 or 2 seed orchards in the next few 

years. Eventually, resistant trees will be used to restore an American 

beech component in BBD-impacted forests and to establish resistant 

trees in unaffected beech stands. The objective of this research is to 

develop regional repositories of resistant beech germplasm and establish seed orchards 

and seed production areas that consist of a genetically diverse population of resistant 

beech. (Paraphrased from proposal written by Dr. Jennifer Koch, USDA Forest Service.) 

The Emerald Ash Borer was detected in two new locations in 

Michigan’s Upper Peninsula in 2007. Both finds - Moran and St. Ignace 

State Forest Campground - were just north (within 15 miles) of the Straits 

of Mackinac (See map below). The current EAB Quarantine now 

encompasses the Moran site, and will be modified again once all 2007 survey activity is 

completed and the St. Ignace site has been delimited. For detailed information on the 

EAB quarantine, visit the MDA website at: http://www.michigan.gov/mda

Photo by 

Jennifer Koch
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2007 EAB Detections 

Map of EAB Detections in the Upper Peninsula

New 2007 EAB detections were the result of trap tree surveys conducted by the MDA and 

Michigan Technological University (MTU). The MTU survey is sponsored by the USDA Forest 

Service in cooperation with the Michigan DNR. MTU used maps of the state’s ash 

resources and state park databases showing visits from residents of EAB infested counties 

to define areas of high EAB risk to focus survey efforts. Trap trees were deployed in state 

and federal parks and campgrounds throughout Michigan and Wisconsin. The survey 

effort also included visual inspections of firewood and ash trees in these and adjacent 

areas. The MDA surveys were more extensive, with over 4000 trap trees in the Northern tip 

of the LP and the Upper Peninsula monitored. 

Hiawatha 

National 

Forest
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Spathius agrili.

The MDNR conducts annual firewood sweeps in December, 

following closure of the firearm deer hunting season. All hardwood 

firewood left at state forest campgrounds and state parks is burned. 

This eliminates the risk of EAB emerging from infested firewood the 

following spring. During the camping season, Parks and Recreation Division employees 

inspect vehicles entering state parks for firewood. MDNR staff conduct random 

inspections of state forest campgrounds. When found, firewood that is not in compliance 

with the EAB quarantine or the MDNR Director’s order is seized and burned. The Director’s 

order prohibits moving ash wood onto state lands unless that ash is without bark attached. 

Guidelines to manage ash (Fraxinus sp.) in stands within and outside of EAB affected 

areas have been developed. Management strategies are influenced by the abundance 

and size of ash trees, and distance from EAB populations. The guide recommends 

reducing EAB vulnerability by reducing ash where abundant, and increasing tree species 

diversity. Vigorous pole-size and smaller ash should be targeted for retention. Removing 

one large ash has a much greater effect on reducing EAB population potential than 

removing many saplings or a few pole size trees. The objective is to create a stand that 

will remain fully stocked, or that will recover rapidly in the event ash is killed by EAB. 

Three exotic EAB parasites from China were released in EAB-infested areas of SE Michigan 

in 2007. The USDA Forest Service Research Station in East Lansing, Michigan released two 

parasites: an egg parasite, Oobius agrili, and a larval parasite, 

Tetrastichus planipennisi. USDA APHIS PPQ released an EAB larval 

parasite, Spathius agrili. 
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Early Rapid Detection – Scolytid 

In cooperation with USDA Animal and Plant Health Inspection Service and Michigan State 

University, the MDNR Forest Health Program conducted a Scolytid Early Detection/Rapid 

Response (EDRR) Survey in southern Michigan in 2007. This effort was part of a nationally 

coordinated survey for non-native bark beetles. Beginning 

in FY 2007, the EDRR Project for non-native bark and 

ambrosia beetles was implemented nationally. A fully 

funded national program will not survey every state 

annually but, at anticipated funding levels, approximately 

1/3 of the states will be surveyed each year. A National 

EDRR Team will set survey priorities, select target species, 

and develop protocols for state participation. 

Nine sites were monitored in southern Michigan, using 

Lindgren funnel traps and 3 types of lures. These lures are 

specific to a variety of conifer- and deciduous-feeding exotic bark beetles in the family 

Scolytidae. 

No species were trapped that were new to Michigan. 

Gypsy Moth 

Gypsy moth (Lymantria dispar) populations were down slightly in Michigan in 2007 with 

25,359 acres defoliated, compared with 31,545 acres in 2006 and 148,525 acres in 2005. 

While rainfall levels were below normal in many parts of the 

state beginning in early June, spring rainfall was average or 

above average and temperatures were cool. This weather 

was favorable to development of the fungal pathogen 

Entomophoga maimaiga and likely contributed to the 

statewide decline in gypsy moth numbers. 
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The Michigan Department of Agriculture no longer sponsors the Cooperative Gypsy Moth 

Suppression Program, which provided communities cost-share assistance for aerial 

pesticide applications. A handful of communities conducted locally-funded programs 

around Michigan in 2007. (Photo Courtesy – Dan Hermes) 

Eastern Hemlock Looper (Lambdina fiscellaria) larvae can be extremely destructive to 

hemlock, balsam fir, and white spruce. Hemlocks may die after one year of 

severe defoliation, fir in one or two years. Loopers have been epidemic in 

isolated areas of the state in the last few years. Populations moved from 

the Eastern U.P. to areas of Northern Lower Michigan and the central U.P. in 

2006. This year saw the second year of defoliation causing 

thin crowns, top kill and some tree mortality. Because 

loopers feed first on lower branches, it is impossible to 

detect feeding damage with aerial surveys until trees are 

heavily damaged. Hemlock should not be harvested in 

stands where defoliation is expected because: 1) Insects 

are concentrated on residual hemlock after cutting; 2) New openings can reduce 

moisture availability by increasing amount of sunlight reaching the forest floor. Drought 

stress further predisposes hemlock to injury; and 3) Careless harvesting wounds trees and 

causes stress, which contributes to stand mortality. Aerial spraying of biological 

insecticides containing B.t. (Bacillus thuringiensis) effectively protects hemlock stands from 

potentially damaging looper populations. 
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Hemlock Woolly Adelgid

The Michigan Department of Natural Resources (MDNR) continues to 

cooperate with the Michigan Department of 

Agriculture (MDA) and Michigan State University in 

efforts to prevent the Hemlock Woolly Adelgid (Adelges tsugae)

(HWA) from establishing in the Northern Lower Peninsula. HWA is an 

exotic invasive insect which feeds on tree sap, killing needles, twigs 

and branches. Infested trees eventually die. HWA was detected on 

native eastern hemlock in the Harbor Springs Area in 2006. In 20 

years of HWA survey activities this is the third time the pest has been 

detected in Michigan. The previous two findings in 2001 were restricted to nursery stock 

that was quickly destroyed. This is the first time that HWA has been found on native 

hemlock. 

All imported hemlock and adjoining native trees were removed and destroyed. The MDA 

also treated a perimeter of hemlock with a systemic insecticide to eradicate difficult to 

detect HWA. Treatments were repeated in the spring of 

2007. These sites will be treated again in the spring of 

2008. The MDA continues to look at other hemlock in 

the area to determine whether additional infested 

nursery stock have been planted in Michigan. 

The MDA established a Hemlock Woolly Adelgid Quarantine in December 2000. The 

quarantine prohibits the movement of hemlock seedlings and nursery stock, logs, lumber 

with bark, uncomposted chips with bark and uncomposted bark from infested counties of 

eastern states and from California, Oregon, Washington and British Columbia. 

The MDNR Forest Health, Inventory and Monitoring Program completed Hemlock Woolly 

Adelgid and Beech Scale Rapid Early Detection Surveys for the fourth straight year. Areas 
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throughout the state with abundant hemlock, either near recreation sites or adjacent to 

nurseries, were surveyed for HWA. If American beech were present in HWA survey areas 

and survey sites were outside of known beech scale areas, they were examined for 

beech scale. No adelgids or new beech scale areas were found in 2007. 

Invasive Plants 

This was the 4th year of an effort to eradicate garlic mustard (Alliaria petiolata) from an 

eighty acre northern hardwoods site in the Eastern Upper Peninsula. 

This is a seven year prescribed burn project which includes follow-up 

use of glyphosate herbicide to treat plants missed by the spring burns. 

Treatments are designed to stop the spread of the plant and 

eventually eliminate garlic mustard. Garlic mustard populations have been greatly 

reduced with few second year, fruit-bearing plants produced. Additional monitoring of 

plant community responses to burning and herbicide treatments is planned for 2008. 

Jack Pine Budworm

The Jack Pine Budworm (Choristoneura pinus pinus) defoliated 158,500 acres in 2007, a 

slight increase from 150,645 acres in 2006. The budworm is the most significant pest of jack 

pine in North America. Stands older than 50 years are most susceptible to damage. Jack 

pine over 50 years old that has suffered 2 or more defoliations during the past 3 years is at 

highest risk of top kill or mortality. 

Damage surveys in 2007 were conducted to assess potential tree mortality and project 

future volume losses. In the Lower Peninsula, affected stands were only lightly or 

moderately defoliated this year and had little or no defoliation in 2006. Little mortality or 

top kill is expected in these stands in 2008; no pre-salvage sales are scheduled but 

defoliation levels will be monitored next season. The management objective is to reduce 

jack pine rotations on state land to 50 to 60 years, significantly reducing the risk of 

budworm-triggered mortality. 
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Jack pine stands in Iron and Dickinson Counties in the southwestern Upper Peninsula are 

experiencing top kill and mortality as a result of repeated budworm defoliation. Harvest 

operations are underway to salvage dying trees and to remove high-risk stands. 

Significant budworm defoliation also occurred in the Yellow Dog Plains in Marquette 

County, the Danaher Plains in Schoolcraft County and in Luce County. In addition to 

older, high-risk stands, defoliation is also occurring in young, sapling- and pole-sized jack 

pine stands. 

Oak Wilt (Ceratocystis fagacearum) continues to spread naturally and artificially through 

much of the Lower Peninsula. Overland spread of oak wilt through firewood movement 

and the wounding of oak by activities such as branch pruning continue 

to plague efforts to slow the spread of this fatal disease. Sap-feeding 

beetles (Nitidulid sp.) responsible for spreading oak wilt are most active 

in the spring and early summer. These small (1/4-inch long) beetles pick 

up spores from diseased trees and transmit them to oak trees that have been injured. To 

slow the overland spread of oak wilt, harvesting restrictions are observed on state land. 

Forests where red oak trees will remain after the harvest cannot be cut between April 15 

and July 15. 

Beginning in 2004, U.S. Forest Service Oak Wilt Suppression funds have supported a joint 

MSU Extension and MDNR effort to rid the Upper Peninsula of this threat to its oak 

resources. Oak wilt has been detected in two counties, Menominee and Dickinson (See 

map above). The objectives of this program are to: 1) Remove oak wilt from the U.P. by 

detecting and treating all infection centers; 2) Educate affected communities to prevent 

the reintroduction of oak wilt; and 3) Demonstrate an approach for detecting and 

effectively treating oak wilt infection centers throughout Michigan. In 2008, 22,053 feet of 
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root-graft barriers were created around 25 oak wilt epicenters using a vibratory plow. Red 

oak within the epicenters will be removed before the spring, 2008 to prevent overland 

spread from infected trees. These treatments will remove oak wilt from approximately 600 

acres of oak forest. Landowner and public education 

was achieved via newspaper articles, training sessions, 

site visits generated via detection efforts and public 

inquiries, and distribution of educational materials. To 

date, 20 miles of root-graft barriers have been 

established and approximately 150 oak wilt epicenters 

removed. With one more year of suppression activities, 

most epicenters will have been treated, greatly 

reducing the potential for overland spread. 

In cooperation with USFS S&PF Unit pathologists, MDNR Forest Health Program conducted 

oak wilt suppression activities on two infection centers in the northern Lower Peninsula. 

Root graft barriers were created by severing 

symptomatic trees and extracting stumps using 

backhoes and excavating equipment. Extracted stumps 

were inverted, placed back into the hole and covered 

with dirt. Only symptomatic trees were treated. Treatment 

areas will be monitored for 3 years and additional 

symptomatic trees will be removed if found. Wood from 

infected trees was burned to prevent development of 

spore-producing pressure pads. 

Michigan 

Oak Wilt Counties 
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Cost analyses indicate that, if effective, this method is more cost-effective than traditional 

root graft barrier installation using a vibratory plow. Also, it can be used in soils too rocky 

to allow vibratory blades to penetrate. 

The Red-Headed Pine Sawfly (Neodiprion lecontei) is an important defoliator of 

ornamental, natural-growing, and 

plantation pines. Heaviest infestations are 

commonly on pines growing under stress, 

particularly those at the edges of hardwood 

forests, on poor soils, and where there is 

heavy competitive vegetation. The sawfly 

primarily infests trees less than 15 feet tall. 

Heavily defoliation results in top kill and tree 

mortality. Moderate to heavy defoliation stunts height growth and forking of the main 

stem often results. Sawfly populations have been active in the eastern Upper Peninsula 

and the northern Lower Peninsula since 2002. Sawfly populations collapsed in Mackinac 

County plantations that were treated with Dimilin from 2003 through 2006. However, the 

sawfly remains epidemic in other areas of the central and eastern U.P., most notably 

western Chippewa, northern Luce and Marquette counties. 

Spruce Budworm (Choristoneura fumiferana) defoliated 24,669 acres in several counties in 

Michigan’s Upper Peninsula. Areas of light to heavy budworm defoliation have been 
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visible for the last few years. Isolated areas of mature to over mature spruce/fir in the 

south central and north central Upper Peninsula have top kill and tree mortality caused by 

repeated defoliations.

Sirex Noctilio Wood Wasp 

EAST LANSING, Mich. -- An exotic wood wasp, Sirex noctilio, has made its way to Michigan, 

according to Deb McCullough, Michigan State University (MSU) 

forest entomologist. 

“The wasp was recently captured in a trap in Macomb County,” 

McCullough says. “The larvae of this insect feed in stressed, dying or recently killed pine 

trees. Sirex noctilio has been an important pest in pine plantations in Australia, New 

Zealand and some South American countries.” 

McCullough says the wood wasp is native to Europe, Asia and North Africa, but was 

discovered in New York in 2005 and in Ontario in 2006. 

“Like many other wood-boring insects, it probably came to North America in solid wood 

packing material and it was likely present for several years before it was discovered,” she 

says. 

The discovery of Sirex has led to many residents’ claims that their trees may be infested 

with the pest. There are some important aspects of the Sirex noctilio capture in Michigan 

that residents need to know before they claim they have seen or have trees infested with 

the pest. 

“First, horntails, including Sirex noctilio, are related to wasps,” McCullough says. “Horntails 

can look very similar to a wasp, and many people will likely mistake the bluish-black wasps 

that they see around their home for a horntail. 

“Second, there are 23 different species or subspecies of horntails that are native to North 

America,” she adds. “Some species colonize pines or other conifer trees. Other horntail 
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species colonize hardwood trees -- 

beech, for example, is a common 

host. Virtually all horntails are some 

combination of yellowish-brown or 

black in color and they all look alike. 

Even entomologists have a difficult 

time trying to distinguish one species 

from another. Native horntails are not 

considered a problem. Because they 

colonize dying or recently dead trees, 

they play an important role in 

decomposition and nutrient cycling.” 

Whether Sirex noctilio will become an important pest of pine in Michigan or other areas of 

North America is yet to be determined, McCullough says. 

“We have many insect species that colonize stressed, dying or recently killed pines,” she 

says. “Sirex wood wasps will have to interact with and compete with those native insects 

for that same pine resource. In addition, we do not yet know if Sirex noctilio is established 

in Michigan or if the insect collected in the trap was simply dispersing from an infestation 

in Ontario. Wood wasps are very good fliers and it’s quite possible this particular insect 

originated in Ontario. Many traps were set in Michigan this year for Sirex noctilio following 

the identification of the infestations in Ontario last year. After horntail flight ends (late 

summer) and once all the horntails collected from traps or trap trees have been 

identified, we’ll have a much better idea of whether Sirex noctilio is actually established in 

Michigan.” 

She also notes that Sirex noctilio will face native natural enemies in North America and 

possibly an introduced biological control. There are at least two groups of native 

parasitoid wasps that will attack the horntail larvae. In addition, an active biological 
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2007 Forest Health Highlight Page 19 

control program that was developed in Australia makes use of parasitic nematodes. 

Methods have been developed to inoculate pines and introduce the nematode into Sirex 

noctilio populations. Research is underway in the U.S. to assess potential non-target effects 

of the nematode. If results indicate that the nematode can be safely released, the 

methods developed in Australia will likely be used to establish the nematode in Michigan. 

More information about Sirex noctilio can be found on several Web sites including: 

http://na.fs.fed.us/spfo/pubs/pest_al/sirex_woodwasp/sirex_woodwasp.htm, 

http://www.aphis.usda.gov/plant_health/plant_pest_info/sirex/index.shtml, and 

http://www.treesearch.fs.fed.us/pubs/12997. 

To determine if you have an insect that could be Sirex noctilio, contact the MSU Plant Pest 

Diagnostic Clinic at 517-355-4536, or your local county MSU Extension office. 

Contact: Robin Usborne 517-432-1555, ext. 169 or Deborah G. McCullough 517-355-7445 

White pine branch mortality has been observed in a number of areas in the Northcentral 

Lower Peninsula. This phenomenon was first noted in 2006 and was significantly more 

wide-spread in 2007. While present across a number of 

habitat types, it is particularly evident in and adjacent to the 

Au Sable and Manistee riverine systems. It was determined 

that white pine blister rust was not the cause of this branch 

mortality. 

Examination of the boles of trees near the affected branches 

revealed numerous small, angular cankers not apparently 

associated with wounds or branch stubs. The identity of the 

fungus causing these cankers is not known. Michigan State 

University will attempt to isolate a causal agent from these cankers from samples 

collected at the site. 
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Ips bark beetles, black staining in the branches and bole, and pockets of resin on the 

affected branches were also observed. Forest Health staff with the Michigan DNR will 

continue to monitor the situation for development of additional symptoms, or spread of 

the problem to other areas. (Photo U.S. Service)

 White pine mortality was observed, in a residential private woodlot in Crawford County in 

the Northcentral Lower Peninsula. Several sapling-sized white pines in this area were killed 

during the current growing season, where no appreciable 

mortality was noted for the previous several years. 

Mortality was scattered, and the trees all seem to have 

been affected at about the same time. Examination of 

the trees consistently revealed the presence of insects in 

the root collar area, accompanied by a black stain, 

presumably related to Ceratocystis or Leptographium. In 

addition, activity of Ips bark beetles was noted in the boles 

of most of these trees, but it is not known whether these 

insects contributed to the death of these trees. The trees 

likely died due to the combined effects of drought, insect 

attack and root injury caused by the black stain fungus. 

DNR personnel will monitor this site for development of additional mortality, and Michigan 

State University will attempt to isolate the cause of the black stain in the root collar area. 

Contributed by Dr. Joe O’Brien, USFS