1999 Forest Health Highlights - Michigan

file:///X|/netsite-docs/lps32615/1999%20Forest%20Health%20Highlights%20-%20Michigan.html[4/2/2015 11:21:59 AM]

The Resource

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 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, water, and reduce soil

erosion.

Special Issues

Incidence of the vascular disease oak wilt has increased in several areas around the Upper

Peninsula and the Northern Lower Peninsula of Michigan. In response, a statewide oak wilt

initiative is underway in cooperation with the Michigan Department of Agriculture and the

Michigan Department of Natural Resources. This effort will focus on detecting new and

established oak wilt pockets across the state, and working with local communities to

suppress the spread of infection centers. 

Detection will be accomplished through ground surveys conducted by state, federal, and

private foresters, consultants, and nursery inspectors. Information is being maintained in a

database that links field observations with extensive GIS datasets. This will be the first time

specialists and resource managers will be able accurately track the occurrence of oak wilt in

Michigan over time. This data will be available to the public on the Web in 2000. 

The introduction of exotic organisms is perhaps the most serious threat to our native forest

ecosystems. Several agencies including the Michigan Department of Agriculture, the U.S.

Forest Service, USDA Animal and Plant Health Inspection Service, university forest

entomologists and the Michigan Department of Natural Resources are preparing contingency

responses to the possible introduction of the Asian longhorned beetle, and other invasive

exotic pests in Michigan. Although uninfested border counties will be surveyed for the pine

shoot beetle in 2000, the comprehensive survey for the PSB will be discontinued in 2000.

Steps have been initiated to rescind the PSB quarantine. This decision is based on the need
1999 Forest Health Highlights - Michigan

file:///X|/netsite-docs/lps32615/1999%20Forest%20Health%20Highlights%20-%20Michigan.html[4/2/2015 11:21:59 AM]

to focus limited resources on more serious pests, and the lack of control measures to slow

down the natural movement of the PSB. Quarantine enforcement will continue until

rescinded.

A fly that attacks the seed heads of the invasive exotic plant spotted knapweed has been

introduced in the Lake States. This insect is establishing very well throughout Michigan.

This is just the beginning. To be successful, other biocontrols must be introduced until the

knapweed's competitive advantage is "normalized". It will then contend for space and

nutrients as do native plants that have evolved with a cadre of natural limiting factors. 

Extreme winds and hailstorms in the past two years damaged red pine plantations in

Northern Lower Michigan and the Upper Peninsula. Resulting branch and stem injuries were

infected by Sphaeropsis sapinea (=Diplodia) causing dramatic top kill and whole branch

flagging in young plantations. This disease causes shoot death, stem cankers and a

phenomenon called collar rot. Collar rot girdles the stem at ground level and can kill

seedlings and small trees. Research at the University of Wisconsin indicates that red pine

seedlings that develop symptoms after planting may have been infected at the nursery. There

are no effective controls once a tree is infected with Sphaeropsis. Avoiding stressful

conditions, like planting red pine on poor sites, can help reduce the incidence of infection.

Harvesting mature red pine trees can help reduce infection on young red pine seedlings and

saplings growing below. 

Pine bark beetle populations have been increasing in the northern Lower since 1997. Red

pine stands stressed by lack of moisture are susceptible to damage by this insect. Adult

beetles fly to stressed red pine trees in the spring and lay eggs. Larvae burrow into the tree to

feed on the live tissue below the bark. Extensive feeding can girdle and kill trees. When

conditions are favorable for bark beetle outbreaks, red pine harvests are restricted to the

winter season. Treetops and branches left on site are chipped or cut and scattered to

discourage adult beetles from using the material to lay eggs.

Other Issues

Michigan experienced a two-fold

decrease in gypsy moth defoliation in

1999, where 176626 acres were defoliated

in the Lower Peninsula. This is down
1999 Forest Health Highlights - Michigan

file:///X|/netsite-docs/lps32615/1999%20Forest%20Health%20Highlights%20-%20Michigan.html[4/2/2015 11:21:59 AM]

from 301,778 acres affected in 1998. In

several aspen and mixed aspen stands,

large aspen tortrix defoliated 69,826

acres in the Lower Peninsula. Gypsy moth

and aspen tortrix were active in the same

stands in many areas. In the Upper

Peninsula, large aspen tortrix populations

were high for the third consecutive year,

defoliating 182,000 acres, with spotty

defoliation on another 535,000 acres. In

some areas of the Upper Peninsula, a

combination of forest tent caterpillar

and tortrix defoliated several aspen and

mixed aspen stands. Bruce spanworm

and spring cankerworm defoliated

105,000 acres of sugar maple stands, and

caused spotty defoliation on an additional

228,000 acres.

The jack pine budworm defoliated 10573 acres in 9 counties in north central Lower

Michigan. Jack pine stands on state land were evaluated in 1999, high-risk areas were

identified based on age and site characteristics, and efforts are underway to harvest these

stands prior to next outbreak. The current Lower Peninsula outbreak is in its third season.

Based on historical information, budworm populations are expected to begin declining

noticeably next season. In the Upper Peninsula, populations have been low for several years,

and populations are expected to increase. Spruce budworm activity in the Upper Peninsula

has been spotty for the last few years with no significant population buildup detected. Thin

cedar crowns were common in central Upper Peninsula in 1999 and were easily mistaken

for spruce budworm defoliation in mixed lowland conifer cover types. A heavy seed year

thinned new foliage and gave cedars a distinct brown color. 

European pine shoot moth damage was common in many parts of the state in 1997 and

1998. The concern that populations were building as they did 30 to 40 years ago subsided in

1999 as little shoot moth damage was detected. European pine shoot moth overwinters on

snow covered lower branch whorls of young red pine. Heavy snows in 1995 and 1996

contributed to a population buildup but low snow accumulations in 1997 and 1998 provided

little protection for larvae and likely triggered a population collapse. 

Damage from windstorms and tornadoes declined in 1999 in Michigan, where it was

limited to isolated timber blowdown on state land. One exception was the tornado that

leveled the town of Comins, Michigan in the northeastern Lower Peninsula. While there

were no injuries, damage to the town and immediate surroundings was extensive. 

Michigan State University has established 50 permanent plots throughout Southern Michigan

to survey the incidence of dogwood anthracnose. Approximately 2/3's of the plots have no

signs of anthracnose. The survey indicates that dogwood anthracnose infested areas are

spotty and occurrence appears highly correlated to suburbs that use landscaping services. The

study also indicates that Michigan has many landscape nurseries with infected stock
1999 Forest Health Highlights - Michigan

file:///X|/netsite-docs/lps32615/1999%20Forest%20Health%20Highlights%20-%20Michigan.html[4/2/2015 11:21:59 AM]

originating from several other states.

Gerald Thiede, 

State Forester 

P.O. Box 30028 

Lansing, MI 48904 

(517) 373-1275

Forest Health Protection 

Northeastern Area 

USDA Forest Service 

1992 Folwell Avenue 

St. Paul, MN 55108 

(612) 649-5261

Updated: December 1999.......

Michigan Forest Health Highlights - Previous Years

98 97 96 95 94

Forest Health Highlights home page | General Regional Highlights

Forest Health Monitoring home page