Fall 2002 - Volume 11, Number 3

Exotic Invasive Species

A Renewed and Continuing Threat to the Forest

by Philip T Marshal, Forest Health Specialist, Indiana Dept Natural Resources, Div Forestry

The expression "Exotic invasive Species' describes species that are found in our forest environment, or any environment. Using the word 'species', we could be talking about a plant, insect, fungus, bacteria, virus or animal. Adding the descriptive adjectives 'Exotic' and 'Invasive', the species of interest takes on a new meaning and impact to the environment that man has under management. In most cases, if not all cases, defining species as exotic invasive have negative impacts to the management goals that man applies to the forest environment or any environment.

An Exotic invasive Species is an organism that is not native to the environment. The species comes into the new environment without the parasites and predators that provide the balance found in its native range. Without the limits provided by parasites and predators, the exotic species can grow and build a population that can dominate the new environment and alter the new environment to a less desirable state. Adding 'Invasive" to describe the species adds a greater negative meaning and a greater risk to the environment and the management goal. Invasive implies that the exotic species can easily and readily spread across the range of the new environment posing a threat to native species it will displace or attack.

Exotic Invasive Species are not new to the environment around the world. Foresters, botanists, wildlife specialists, ecologists and other professionals who manage our environment are constantly concerned about and have to manage Exotic Invasive Species. Our forests have been impacted by Exotic invasive Species for centuries and continue to be an everyday event. Unfortunately, the existence of Exotic invasive Species around the world and in the U.S. has been the result, knowingly and unknowingly, of man. With the expansion and speed of international trade, new Exotic invasive Species arrive in the U.S. every year - at least in recent years, it seems to be an annual event.

As a forest pathologist and entomologist, I focus on insects, fungi, bacteria and virus that attack the trees resulting in disease. Thus, I am more interested and aware of exotic invasive forest insects and diseases. And, as I said, Exotic Invasive Species have been introduced into our forests for years. Examples of exotic forest insect and disease problems from the post include Chestnut Blight, Dutch Elm Disease, Japanese Beetle, and Gypsy Moth. In recent years, Pine Shoot Beetle, Tomicus piniperda, was introduced into the Great Lakes area. A pest of pine trees, the beetle has slowly moved south in Indiana and has now been detected as far south as Brown County. Although it is an exotic species, it is not a serious threat to pine management in Indiana because the forests are managed for hardwood species. But, pine shoot beetle poses a risk to the management of pine in southeastern U.S. because that area has vast pine forests that the beetle can attack. For information on pine shoot beetle visit this web site -http://www.ceris.purdue.edu/napis/pests/psb/

After Pine Shoot Beetle, the Asian Longhorn Beetle (ALB),Anoplophora glabripennis, came to the Midwest. First found in New York City in 1996, Asian Longhorn Beetle was found in Chicago in1998. This beetle poses a major risk to maples, the preferred species attacked in the U.S. Maples become the common street and urban tree following the death of elm from Dutch Elm Disease. And, maples are a common component of the forest. Thus, ALB poses a serious threat to the forest, both rural and urban. The efforts to eradicate ALB are having some success in Chicago as only 19 infested trees were detected in the last year. However, more ALB locations have been detected in the New York City area and the eradication goal is not progressing as well. ALB has not been detected in Indiana and other states. The adults are large

(3/4 to I inch long), active beetles that are shiny black with irregular white spots. The long antennae have alternating white and black bands. They emerge throughout the summer and it is unlikely to see an adult this late in the year. Symptoms include sawdust-like frass on the ground, dead and dying branches in the canopy and large (3/8 inch diameter) circular exit holes left by emerging adults. If you believe you have ALB, please contact the Division of Entomology & Plant Pathology (317-232-4120), your district forester or myself (812-358-3621 ). For information on ALB, visit these U.S. Department of Agriculture web sites - http://www.na.fs.fed.tis/spfo/alb and http://www.aphis.usda.gov/oa/alb/alb.htm or the Department of Natural Resources website - http://www.in.gov/dnr/entomolo/pestinfo/asian.htm.

The newest Exotic Invasive Species to be discovered in the Midwest is another beetle, the Emerald Ash Borer (EAB), Agrilus picnipennis. This beetle was found in and around Detroit, Michigan this June and July. As the name implies, it feeds on ash trees. Currently found in 6 Michigan counties, surveys to detect the beetle are occurring across the range of ash. This beetle is a relative to the Bronze Birch Borer and the Two Lined Chestnut Borer, which are common beetles that attack white birch and the oaks, respectively. EAB is native to Asia and the information on its biology and ecology is very limited. Defining the range of EAB in the forest may be difficult because symptoms of the disease Ash Yellows and EAB are similar. Ash Yellows is found throughout the range of ash and is present in the forests of Indiana, especially northeastern Indiana. With the limited knowledge of EAB's biology and ecology, it is not known if Ash Yellows trees will encourage and aid the spread of EAB. But it is a good assumption that they may support and aid EAB, and EAB may hasten the death of Ash Yellows trees. Like Bronze Birch Borer, EAB adults produce a 'D" shaped exit hole in the branches and stem. The adult is green and 1/4to 1/2 inch long and is present from late May to early August. If you have ash trees with extensive dieback, epicormic sprouts in the lower tree crown or along the upper bole, you may have EAB. But, you may also have ash yellows. If you have these symptoms and observe "D" shaped holes in the bark, please contact the Division of Entomology &Plant Pathology (317-232-4120), your district forester or myself (812-358-3621). For information on EAB, visit this USDA Forest Service website - http://www.na.fs.fed.us/spfo/eab  and the Michigan Department of Agriculture website http://michigan.gov/mda  using key words 'ash borer'.

Moving from a beetle to a disease, Sudden Oak Death (SOD),  Phythophora ramorum, was first reported in 1995 in California. Presently found in California and Oregon, the disease attacks and kills tanoak, coastal white oak and black oak. Other hosts include Rhododendron, huckleberry, bay laurel, madrone, bigleaf maple and California buckeye. Just recently the fungus was isolated from Doug Fir and Redwood. In the eastern U.S., red oak and northern pin oak are at risk because tests showed them to be highly susceptible. Last year the cause of SOD was identified as the fungus, P. romorum. Although only in California and Oregon, SOD poses a great risk to the oak resource of the Midwest and eastern U.S. Approximately, 40% of Indiana's forest is composed of oak species. Thus, the introduction of SOD into Indiana adds one more disease threat to oak. Oaks have enough to attack them with Oak Wilt, Oak Decline and gypsy moth. Oak wilt has been present in Indiana for many years and is a common killer of oak in northwestern Indiana. Oak Decline associated with drought, armillaria root rot and two-lined chestnut borer is common across all of Indiana. In the last 10 years, gypsy moth has entered the state (northeastern Indiana) and is approaching the time when it will start to defoliate the oak forest. Therefore, Indiana's oak resource does not need to have another exotic species attack it. To date, SOD has not been found in the Midwest or Eastern U.S. For more information on Sudden Oak Death, visit these web sites-http://www.na.fs.fed.us/sod/index.htm   and http://www.suddenoakdeath.org.

For other information on exotic invasive species, visit these web sites.

THE EXOTIC FOREST PEST INFORMATION SYSTEM FOR NORTH AMERICA - http://www.exoticforestpests.org/english/english.htm INVASIVE ORGANISMS - http://www.invasive.org/

INSECTS - http://www.invasive.org/insects.cfm

DISEASES - http://www.invasive.org/diseases.cfm

USDA, APHIS,PPQ, Invasive Species and Pest Management - http://www.aphis.usda.gov/ppq/ispm

 

The following websites provide pictures and information on forest insects and diseases:

FORESTRY IMAGES - http://www.forestryimages.org/

FOREST PESTS, Insects - http://www.forestryimages.org/insects.cfm

USDA, FS, S&PF, St. Paul Field Office - http://www.na.fs.fed.us/spfo/

If you have q question regarding the health of your tree or forest, please call, email, or write.  I am happy and willing to assist you as best I can.

Philip T. Marshal, Forest Health Specialist

Vallonia State Nursery

2782 W Co Rd 540 S

Vallonia, IN  47281

812-358-3621, pmarshal@hsonline.net, pmarshall@dnr.state.in.us

 

 

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