1998 Michigan Forest Health Highlights
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.

major forest types in Michigan table

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 interagency oak wilt initiative is underway, lead by 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 collected will be made available on the Web in 1999. In addition, new high-resolution satellite imagery is being evaluated for use as an oak wilt detection tool.

Michigan has experienced a hundred-fold increase in gypsy moth defoliation in the past two years, with 301,778 acres affected in 1998. Much of the defoliation occurred in the oak and aspen types of the east central Lower Peninsula, and in the mixed oak types of the southwestern Lower Peninsula. Dry spring conditions have not been favorable for development of the gypsy moth fungal pathogen Entomophaga maimaiga during this period. In recent years, Entomophaga has been credited with dramatic collapses of local gypsy moth population in the Lower Peninsula.

The 5-year Slow the Spread Project in Michigan's Upper Peninsula ended in 1998. The western Upper Peninsula will continue to be part of a multi-state pheromone trap monitoring effort. An isolated gypsy moth infestation detected in Delta County in the south central Upper Peninsula will be the site of public education efforts designed to help residents make informed decisions about dealing with this pest.

A study by Michigan State University is looking at the role of temperature in gypsy moth egg mass mortality. Preliminary indications are that exposure to high daytime temperatures in late winter may account for significant mortality of egg masses located on tree trunks above snowline.
1998 defoliation in Michigan
The jack pine budworm defoliated 63221 acres in 9 counties in north central Lower Michigan. Several stands have suffered two consecutive years of moderate to heavy defoliation, and some topkill and mortality is expected in 1999. Extensive pre-salvage operations are underway in the region to harvest older, high-risk stands of jack pine.
Other Issues
Windstorms and tornadoes damaged 70,241 acres of forestland across the two peninsulas in 1998. A widespread, straight-line wind moved across Lake Michigan on May 31 and damaged several stands across the central and northern Lower Peninsula. Salvage efforts focused on removal of damaged pine to reduce the risk of bark beetle attack..

Sphaeropsis shoot blight-damaged red pine in several stands in the Northern Lower Peninsula and the Upper Peninsula. Plantation and natural red pine growing in the open and under mature red pine overstories were affected. In several cases, infection was traced to wounds caused by hailstorm damage. Sphaeropsis damage in red pine growing west of Manistique in the Upper Peninsula was occurred when infection occurred in wind-damaged branches.

Low levels of spruce budworm defoliation were detected in isolated areas in the South-central and Western Upper Peninsula and on Drummond Island. This may be the beginning of a regionwide outbreak, although historical records would indicate that a budworm outbreak is still a few years off. The last epidemic began in the late 1960's and ended in the early 1980's. Spruce plantations with minor balsam fir components have suffered periodic defoliation from spruce budworm since the collapse of the last epidemic.

Porcupine damage was at an all time high in Upper Peninsula red pine plantations. Aerial photography was used to document and assess damage in the central part of the peninsula.

Complexes of spring defoliators were common in Upper Peninsula hardwoods last year. Bruce spanworm and spring cankerworms damaged sugar maple in many areas. Localized areas of heavier defoliation quickly reflushed by mid-June. This could signal a building epidemic. Based on historical records that point to a ten-year cycle, forest tent caterpillar populations are expected to build in 1999. The last outbreak occurred in the late 1980's and early 1990's.

Projects
The Michigan Impact Monitoring System (MIMS) is a long-term monitoring effort that began in the early 1990's in cooperation with the University of Michigan and the Department of Natural Resources. Extensive measurements are made each year on over 600 forested plots located in oak, aspen and northern hardwood stands across the Lower Peninsula. To date, the data indicates that the region's forests are generally healthy, with the exception of the northern pin oak type in the north-central part of the peninsula. Age, drought stress, gypsy moth and other stressors have combined to cause significant mortality in this type. Oak regeneration is also poor across much of this type, where feeding by deer has also been a factor. Competition from red maple on many oak sites is becoming a serious problem. Prescribed burns and herbicides are among the tools being considered by land managers in an effort to maintain oak in these areas

The Basswood Decline Project continues to examine the causes of a decline detected in the northern hardwood type by the MIMS plots and by the Forest Health Monitoring (FHM) System. Several plots established in stands with a basswood component are tracking growth and vigor of basswood trees. In addition, surveys are being done to determine the insect complex responsible for repeated basswood defoliation in the Lake States.

A study is underway to evaluate the use of commercially available and native mycorrhizae at Wyman State Nursery in Manistique, Michigan in cooperation with Michigan Technological University. The study will assess whether Rhizopogon spp. and native Laccaria spp. can successfully infect nursery red and jack pine seedlings. The study will also evaluate a 14-year-old planting of mycorrhizae inoculated seedlings on the Baraga Forest Unit to see if the fungi are still active.

In cooperation with Michigan State University, a study is under way to look at alternative methods of regenerating white pine in Michigan. White pine weevil and white pine blister rust incidence will be assessed in relation to tree growth, site and stand characteristics in white pine stands in the Upper and Lower Peninsula. Test plots will also be established to evaluate white pine regeneration methods on abandoned agricultural land, when underplanted below a hardwood overstory, and in mixed species stands.

For more information contact:

Gerald Thiede,
State Forester
P.O. Box 30028
Lansing, MI 48904
(517) 373-1275
Michigan Logo

Forest Health Protection
Northeastern Area
USDA Forest Service
1992 Folwell Avenue
St. Paul, MN 55108
(612) 649-5261

Northeastern Area, S&PF logo
Updated: December 1999.......



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