1994 Forest Health Highlights


The Resource

There are over 2 million acres of woodlands in Iowa largely controlled by private ownership (92%). These woodlands are dominated by oak-hickory and sugar maple-basswood in the uplands and silver maple-ash-cottonwood in the bottomlands.

Iowa's woodlands provide over 7,000 jobs in the wood products industry. There are about 300 manufacturers ranging from sawmills and pallet shops to fine furniture manufacturers, with annual sales of $860 million. In addition, Iowa's woodland are also critical for soil conservation, water quality, wildlife habitat, outdoor recreation and aesthetic pleasures. In communities, trees are a vital part for energy conservation, property values and community appearances.

Of the forested area:

Major Forest Types
Special Issues

Counties Declared Federal Disaster  Areas Iowa woodlands continue to face damage from uncontrolled livestock grazing, unsustainable management practices, and industrial and residential development. Although the state gained over ½ million acres in woodlands in the last 20 years, timber quality is for the most part declining. In cities and towns across the state, tree removals exceed tree planting and lack of tree maintenance efforts like pruning and gradual tree removal occurs only after natural disasters, such as ice storms, tornadoes, or floods.

Oak wilt is currently the most serious, persistent, forest health issue. An estimated 8,800 acres, mainly red oaks, are affected by this disease. Severing root grafts between infected and healthy trees, removing recent dead, and preventing wounds are the best means of managing the disease.

Oak decline is caused by drought and other stresses predisposing oaks to two-lined chestnut borer and other secondary insects and pathogens.

The flood of 1993 is having lingering effects on the health of forests. Over 97,500 acres of forest in 44 counties sustained standing water for more than 14 consecutive days. Flood stress predisposes trees to attacks by pests. There were over 11,000 acres of tree mortality in bottomland areas due to flooding.

The invasion of gypsy moth with its destructive potential is always looming. Infestations in nearby states will continue to pose a threat of introducing moth populations. Vigilant monitoring by trapping to identify isolated populations has thus far prevented Iowa forests from becoming generally infested.

In 1994, efforts centered on male moth trapping surveys in all 99 counties involving a total of 5,797 traps and treatment of a 90 acre infestation in eastern Polk County. The moth trapping yielded the largest male moth catch to date; an increase of 50% over 1993. Investigation efforts determined that infested nursery stock a private wholesaler in Michigan distributed through local discount retail stores and garden centers was the main culprit. It is expected that further infestation resulting from this infested nursery stock will occur over the next 5 years.

Other Issues

Counties with Ash Yellows Detected The Iowa DNR is partners with other government agencies, universities and green industry consultants in the "Iowa Forest Health Task Force". This Task Force identifies forest health issues, coordinates monitoring programs and develops strategies to manage forest health needs.

Iowa DNR foresters provided direct technical assistance to communities that suffered severe natural disasters such as the tornadoes in LeMars, Decorah, and Cresco, ice storms in Ottumwa, Albia, Fairfield, Mount Pleasant and Muscatine, and herbicide exposure in Chapin due to a chemical plant fire.

Regional Surveys

Through a cooperative project with the USDA Forest Service and the Iowa DNR, Iowa State University Department of Plant Pathology coordinated an applied research study of ash yellows, a potentially serious problem of green and white ash trees common in Iowa communities. Preliminary results seem to indicate this pathogen is present, although other problems also are affecting declining ash trees. Follow-up studies and management recommendations will be developed during 1995.

For More Information

William Farris, State Forester
Dept. of Natural Resources
Wallace State Office Building
Des Moines, IA 50319-0034

(515) 281 - 5385

Forest Health Protection
USDA Forest Service
1992 Folwell Ave.
St. Paul, MN 55108

(612) 649 - 5261

September 1995

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