Tom Kimmerer: Aliens & Pests

Conifers getting the ax in England

Thu, 30 Jun 2005 02:48:14 GMT

The Forestry Commission has announced plans to replace non-native trees in England's forests with native species. The intent is to restore the forests to something resembling the forests of 100 years ago, and to make forests more attractive for wildife and recreation. Up to 20 million trees will be removed over a 20 year period. Reduction of conifer shade should allow native species to reproduce, though enrichment planting will also be funded. Up to 30% of England's forests consist of ancient woodlands, stands over 400 years old, but which include lots of non-native conifers. The government had encouraged establishment of conifer plantations which today account for 15% of England's forests. Ironically, the government had paid for establishment of the conifer plantations that it is now paying to remove.

Seed parasites control development in Douglas-fir seeds

Thu, 30 Jun 2005 02:34:41 GMT

A seed is a wonderful place to live if you are a small insect. Protected by the seed coat and the fruit or cone, nourished by storage compounds like starch and fats, a developing insect has everything it needs. Many insects oviposit (plant eggs) directly into developing embryos. If an insect makes the wrong choice and oviposits into an unfertilized ovule, the developing insect may be out of luck. In conifers, unfertilized ovules become empty seeds, and the tree puts no resources into empty seeds.

Patrick von Aderkas of the University of Victoria and his colleagues found that some insects can avoid making the wrong choice by making the plant feed a larva even if the ovule was not fertilized. A tiny chalcid wasp, Megastigmus spermotrophus (Hymenoptera: Torymidae), deposits eggs in Douglas-fir ovules before they are fertilized. As the wasp larva develops, resources are directed to the seed just as if it had been fertilized. Instead of depending on the tree to supply resources to a fertilized see, Megastigmus manipulates seed development to its own advantages.

von Aderkas P et al 2005 Seed parasitism redirects ovule development in Douglas fir. Proc. Royal Society B Early Online Publishing

Corps of Engineers plants elms

Mon, 20 Jun 2005 17:20:47 GMT

The US Army Corps of Engineers is planting American elms, Ulmus americana, on a man-made island in the Mississippi River. The Corps planted 21 American elm saplings on Eagle Island to replace other species washed away in a flood. Elms once were a dominant species on Mississippi River bottomlands until they were nearly wiped out by Dutch elm disease. The new saplings come from trees with at least some resistance to the disease. The planting program is part of the US Forest Service American Elm Restoration Project.

Watching for sudden oak death in Georgia

Mon, 20 Jun 2005 17:12:25 GMT

Georgia residents are being asked to watch plants in their yard for signs of disease in an attempt to detect infection with Phytophthora ramorum, the fungus the causes sudden oak death. Special attention is being paid to camellias, lilacs, viburnum, azaleas, rhododendron and mountain-laurel. These plants are known hosts for the fungus, which usually causes leaf spots or twig dieback. The fungus can be fatal to oak trees, and the program is an attempt to eliminate the disease from home gardens before Georgia's valuable and extensive oak forest is infected. Ornamental plants were sent to Georgia from infected Monrovia nurseries in California, so state agriculture authorities suspect that infected plants are in the state. Georgia authorities quarantined plants shipped from Monrovi and other California nurseries, but not until over 49,000 plants had been sold.

Washington D.C. acts to conserve American elms

Sat, 18 Jun 2005 14:13:19 GMT

Scouts in Washington D.C., equipped with handheld computers, are surveying 8.500 American elms, Ulmus americana, on streets and city property. The scouts are looking for symptoms of Dutch elm disease. Trees with symptoms are reported to urban foresters, who then examine the trees further and prescribe treatment if necessary. The city, which once had over 25,000 American elms, has not surveyed trees in several years. With the infusion of funds from Casey Trees, scouting is now possible. American elms can be conserved through a combination of treatment and sanitation, but scouting is the first requirement. The National Park Service has a comprehensive program to preserve elms on Federal property

Scouting beetles in Central Park

Sat, 18 Jun 2005 13:24:24 GMT

National Public Radio has a story by Margot Adler about smoke jumpers climbing trees in and around Central Park looking for Asian longhorned beetle. The story includes vivid descriptions of tree climbing.

Previous story: Smoke Jumpers in Central Park

Adult Asian longhorned beetle, Anoplophora glabripennis. Photo courtesy APHIS, US Department of Agriculture

Emerald ash borer update: Costs climbing quickly

Sat, 18 Jun 2005 03:02:30 GMT

In the two years since the "EAB" was first found in Ohio, over 200,000 trees have been cut down in an effort to confine the infestation. As we have reported previously, new outbreak areas have been found this year. Ash removal has been paid for by funds from the US Department of Agriculture. As the borer infestation spread, costs may be shifted to land owners. At least 10% of all trees in Ohio are ash trees (of several species). The Ohio state forestry division estimates that if the infestation spreads throughout the state, direct costs for removal could top $1 billion. This does not include the cost of the lost of ash trees in forests, including the timber value and the loss of ecosystem services. Nor does it include the cost of street tree removal by cities or the cost of increased heat loading of city buildings with the loss of shade trees.

In Ann Arbor, Michigan, residents will probably vote in November on a referendum to allocate $4 million for ash removal in the city. This does not include the cost of tree replacement. Timely removal is critical for controlling the spread of "EAB" but also to remove hazardous trees. Ash trees attacked by "EAB" die quickly and become hazardous, with falling dead limbs and entire trees prone to falling.

Some smaller towns are trying to head off the borer by using state and federal funds to replace ash trees before the borer arrives. Bowling Green, Holland, Rossford, Sylvania and Rossville Ohio are removing ash trees and replacing them with species that are not susceptible to "EAB".

"EAB" information can be found at http://www.emeraldashborer.info.

Adult emerald ash borer, Agrilus planipennis. Photo by James Zablotny, US Department of Agriculture

Emerald ash borer update

Wed, 15 Jun 2005 17:23:41 GMT

Roving bug-detection patrols will be scouting southwestern Ontario this summer looking for evidence of "EAB". The inspection areas are mostly outside Essex County and Chatham-Kent, where thousands of trees have been cut to stop the spread of the Asian insect, which is lethal to ash trees. Inspectors will be visiting sawmills, private campgrounds and provincial parks looking for ash firewood that might have been brought in from infested trees. Last year, 22 fines of C$400 were imposed on people who illegally moved firewood out of the quarantined areas. Movement of wood by people is a much greater threat than natural movement of the beetle, since firewood can be hauled over long distance in a short time. Adult beetles have begun emerging in Ontario, and will be colonizing new trees However, the extent of new damage will not be known until fall or spring, after larvae have fed on the tree stems and girdled the trees.

In Ohio, tree climbers have inspected trees in Maumee Bay State Park and found beetle larvae in seven trees. The trees have been removed. Ash trees within 200 yards of the infested trees were girdled to create 'trap trees.' Stressed trees are more attractive to ash borers than unstressed trees. Girdled trees are more attractive to adult beetles than ungirdled trees and trap trees may attract all the emerging adults, preventing them from flying further afield and spreading the infestation. Trap trees will be removed next spring before adult beetles emerge. The effectiveness of this strategy is not known. It is probably less effective than removing all ash trees in the area, but removal budgets are tight.

Adult emerald ash borer, Agrilus planipennis. Photo by James Zablotny, US Department of Agriculture

Tangled Bank

Wed, 15 Jun 2005 16:49:10 GMT

The latest Tangled Bank is up at Geomblog. Tangled Bank is a blog carnival for science writers. The current offering has lots of great articles and is worth a visit.

Emerald Ash Borer: conflicts between landowners and state

Mon, 13 Jun 2005 17:04:17 GMT

There are continuing conflicts between property owners and state authorities trying to enforce ash tree removal to prevent spread of "EAB". We have previously reported several stories on these conflicts. In Port Huron, MI, property owners are trying to stave off the ash removal program by treating the trees with systemic pesticides known to deter the beetle. However, the treatments are expensive and need to be repeated annually with no end in site. State authorities have not agreed to permit treated trees to remain. Since the state has no guarantee that the property owner will continue treatment, or that the treatment is 100% effective, authorities are unlikely to permit the trees to stand.

The "EAB" control program requires removal of healthy ash trees within 200 ft. of infested trees (farther in some states). Property owners often do not recognize the need to remove apparently healthy trees. It is a difficult task for agricultural authorities to sell property owners on the need to remove trees, especially prized shade trees, when there is nothing wrong with them. This is a public relations problem for the states trying to prevent spread of the "EAB".

Adult emerald ash borer, Agrilus planipennis. Photo by James Zablotny, US Department of Agriculture

Emerald ash borer extends range in Ohio

Mon, 13 Jun 2005 16:54:26 GMT

The "EAB" has spread in northern Ohio, and is now in downtown Toledo and Maumee Bay State Park. State officials are planning aggressive ash tree removal programs for both areas. The Maumee Bay infestation is particularly worrisome:

"The most disconcerting news for state officials was the discovery of infested trees at Maumee Bay State Park in eastern Lucas County. That means the beetle has moved perilously close to the Lake Erie shoreline and could spread eastward across northern Ohio - something officials have been fighting to avoid. They fear the pest will be much harder to stop if it enters wetland areas in state preserves and the Ottawa National Wildlife Refuge in Ottawa County that have limited road access.

"I can confirm it has been infested," Lee Anne Mizer, agriculture department spokesman, said yesterday of Maumee Bay State Park. She refused to elaborate, indicating the state plans to discuss details on Monday." - Toledo Blade

Adult emerald ash borer, Agrilus planipennis. Photo by James Zablotny, US Department of Agriculture

Winter moths defoliating in New England

Mon, 13 Jun 2005 16:49:13 GMT

The winter moth, Opheroptera brumata, was introduced into North America from Europe. Caterpillars of the winter moth are summer defoliators of maples, apples and blueberries. Long a problem in southern Canada, the winter moth has established itself in Massachusetts and Rhode Island. Winter moth adults emerge in November and December, and many communities in Massachusetts had dense flights of the moths last fall. These areas are now seeing extensive defoliation.

Defoliated trees are weakened somewhat, but spring defoliations are generally followed by a flush of new growth and recovery. Several years of consecutive defoliation can reduce tree vigor, especially if other stressors such as drought also reduce vigor. Defoliation can severely depress fruit production. The winter moth is unlikely to become as serious a problem as the gypsy moth, and effective biological control agents are already known. In Canada, winter moths have been controlled by the introduction of a predatory wasp, Cyzenis albicans, and Massachusetts authorities are raising trial populations of the wasp. It could take several years before wasp populations are high enough to control the winter moth.

The last few years have seen major increases in defoliation from multiple causes in New England. Defoliation by native insects is at all-time high levels. Insect outbreaks are often regulated by weather. Mild winters, such as we have had in recent years, permit higher insect populations to survive. Global warming is thus a likely cause of increased insect infestations.

A tree mystery: Death of a hemlock

Tue, 31 May 2005 18:45:01 GMT

A hemlock tree, planted in a yard 14 years ago, died suddenly. The homeowner left town with the tree apparently healthy and returned two weeks later to find the tree had lost all its needles. On inspection, all the above-ground parts of the tree were dead. We excavated the tree with an Air Knife to see if there were below-ground signs or symptoms that might indicate the cause of death. We found extensive injury to the cambium, phloem and xylem below the ground level of the tree.

Stem of a dead hemlock showing extensive injury.

What caused all this damage? Read more for the solution.

Alien woodwasp in New York

Tue, 24 May 2005 18:13:44 GMT

A single female specimen of Sirex noctilio, a European woodwasp has been found in Fulton NY. The woodwasp has been devastating pine forests in the southern hemisphere and has the potential to do the same in North America. The woodwasp deposits a toxic mucus and spores of a toxic fungus, Amylostereum areolatum, when it lays eggs in the sapwood of conifers. Primarily a pest of pine, other conifers can be infested as well.
The insect was discovered by E. Richard Hoebeke, a Cornell University entomologist, during a routine survey of bark beetle traps from throughout New York. The Sirex specimen is the first female ever caught in the eastern US, but it is highly unlikely to be the last. A female was found in Indiana in 1992 and several males have been intercepted. Federal and state agencies are setting up traps throughout the region to determine whether there are other woodwasps present.

If more woodwasps are present, and they probably are, a battle like the ones underway against the Emerald ash borer and Asian longhorned beetle will ensue. Attempts will be made at quarantine. There is an established control method in use in the southern hemisphere using a parasitic nematode

Photo by Kent Loeffler, Cornell University

Emerald Ash Borer Awareness Week

Tue, 24 May 2005 11:22:43 GMT

Governors of three states, Michigan, Ohio and Indiana, have declared the week of May 22 Emerald Ash Borer Awareness Week. The goal of the declaration, coming at the beginning of the summer travel season, is to try to slow the spread of the insect. People are the major long-distance vectors of the insect, carrying firewood and other wood products out of quarantine areas into uninfested areas. With the season for beetle emergence approaching, this is an especially critical time to avoid spread of infested material.

Emerald ash borer: firewood transport to UP banned

Tue, 24 May 2005 11:10:02 GMT

As the summer camping season begins, Michigan has announced a ban on firewood taken across the Mackinac Bridge to the Upper Peninsula (UP). Checkpoints will be set up on the highway to the bridge and firewood will be confiscated from campers travelling to the UP.

This week is Emerald Ash Borer Awareness Week, as the season for emergence of the beetles approaches. Michigan authorities hope to prevent further outbreaks of the beetle in the UP. To date, there have been "EAB"s found in only one location in the UP.

American chestnuts on Ohio surface mines

Tue, 10 May 2005 14:39:12 GMT

Ohio has begun planting American chestnut on surface mines in the eastern part of the state. The project is part of the American Chestnut Foundation's effort to restore chestnut to its former glory, uses blight-resistant hybrids of American and Chinese Chestnut. The breeding project, expected to take at least 100 years, mates American chesnuts with Chinese chestnuts and selects resistant progeny. These will then be backcrossed through consecutive generations to select for trees with nearly pure American chestnut characters and genes, but with the blight resistance of Chinese chestnut. The project is led by Brian McCarthy, a forest biologist at Ohio University.

American chestnut was once the dominant species in mid-slope Appalachian forests. They accounted for up to 70% of the stocking (basal area of all the trees) in these forests. Chestnuts produce starchy nuts rich in protein and fat and were an important food resource for wildlife, and for people and their livestock. The tree was wiped out by an epidemic of chestnut blight, caused by the fungus Endothia parasitica. The blight killed billions of trees in only a few years as it swept down the Applachians. My friend Junior Marshall recalls that one year at Robinson Forest the fall colors of the chestnut were magnificent and the following year (1939), they were all dead.

Surface mines may seem an odd place to plant chestnuts. However, they appear to do well in some mine sites. I have found American chestnut on mine spoils in eastern Kentucky.

Smokejumpers in Central Park

Fri, 29 Apr 2005 18:48:23 GMT

The US Forest Service has assigned a group of five smokejumpers (professional forest fire fighters) to Central Park in New York. Their goal is not to fight fires, but a more insidious problem, the Asian longhorned beetle (Anaplophora glabripennis). The smokejumpers have been trained in tree climbing methods and are inspecting trees in and around Central Park from the canopies. Visual inspection from the ground has proved ineffective in finding small outbreaks of the tree-killing beetle. The inspection comes after two trees with active infestations were found a few blocks from the famed park. By inspecting trees from the canopy, authorities hope to locate and destroy any beetle infestations before they overwhelm the park. The smokejumpers have already found one infested elm tree near the park out of 1700 trees inspected so far. That tree will be removed and destroyed.

Ash borer eradication underfunded

Wed, 27 Apr 2005 18:34:47 GMT

Cutting down all the ash trees near infested trees is the only effective measure to try to control "EAB" ("AP"), but it is expensive. The USDA has refused to release funds designated for "EAB" control, and Michigan now lacks adequate money to eradicate trees. Instead, Michigan officials are turning to the trap tree method. Since Agrilus beetles are preferentially attracted to stressed trees, girdling a tree makes it into a trap tree, one that should be attractive to female beetles looking for a place to lay eggs. The trap tree method is useful for measuring insect populations, but it is not an effective method to get rid of beetles.

Michigan requested $37.8 million of federal funds for beetle control, but received only $11 million. The USDA has given no reason for the shortfall. The USDA has so far given no reasons for the lack of funds, which were appropriated by Congress.

"EAB" eradication has also been underfunded in Ohio, where $11.6 million was requested but only $8 allocated. Michigan and Ohio congressional representatives are trying to get USDA to free up more funds.

Even if USDA comes up with the full funding, eradication efforts are likely to fail. There are too many opportunities for people to break the quarantine on infested counties, by carrying logs and firewood away. No amount of eradication will stop the beetles until people cooperate fully in the quarantine.

Geneva Convention won't save trees

Tue, 26 Apr 2005 15:11:03 GMT

A Florida couple has lost their latest effort to save the grapefruit trees in their back yard. Florida is struggling with citrus canker, caused by the bacterium Xanthomonas axonopodis pv. citri. Quarantine rules require all trees within 1900 ft. of an infected tree to be destroyed. The Boca Raton couple, Edmund and Laura Gerstein, sued to stop their two grapefruit trees from the ax. They claimed that the Geneva Convention prohibited government destruction of civilian food sources in time of war. Claiming that the war on terrorism and the Iraq war could cause a food shortage, the Gersteins posted the Geneva Convention on their front door and tried to stop agriculture officials from cutting the trees. The court didn't buy it and the trees have been cut down.

Mammoth Cave dogwoods threatened

Mon, 25 Apr 2005 20:58:13 GMT

More than half the flowering dogwoods (Cornus florida) in the forests of Mammoth Cave National Park are dead. The trees have succumbed to dogwood anthracnose, caused by the fungus Discula destructiva. While over 3/4 of trees in the park are dead or infected, park ecologists may be able to slow the spread of the disease by managing the forest canopy: the fungus spreads most rapidly in moist understory conditions. These are also the conditions in which dogwoods grow best, but they do well in sparser upland forests as well. Controlled burning may help open up canopies to sunlight, reducing humidity and the threat of infection. (Oddly, the AP article about this issue refers to these trees as 'white dogwoods', rather than the correct name flowering dogwood).

Emerald ash borer: fines for moving infested firewood

Mon, 25 Apr 2005 20:00:36 GMT

A Michigan tree service owner has been fined $300 for taking "EAB" ("AP") infested firewood from the Detroit area to the Upper Peninsula. Orville Wonsey, owner of OGW Tree Service had a contract to cut infested ash trees in the Detroit area, and was convicted of the misdemeanor count of insect pest and plant disease quarantine violation. Wonsey had taken firewood to two counties, Gratiot and Luce, and sold it, according to agriculture officials. Michigan legislators are now looking to increase penalties for quarantine violations.

Moving infested wood is how the "EAB" gets around quickly. Left to its own devices, "EAB" spreads very slowly. The sole long-distance vector ash borers is people. It is especially egregious for a tree service operator to be involved in spreading this serious pest. It is impossible for such a person to claim ignorance.

Update: The question of whether "EAB" is in the Upper Peninsula is not clear from the news article linked above. Gratiot county is in lower Michigan, and there is an infestation. Luce County is in the UP, and it is not clear whether the movement of firewood by Mr. Wonsey or others has led to an infestation. Time will tell. Thanks to Jeff B. of the Forestry Forum for clarifying this.

Emerald ash borer in Hancock County, Ohio

Tue, 12 Apr 2005 15:39:37 GMT

"EAB" ("AP") has been found in Hancock County in northeastern Ohio. Infested trees were found just south of the Wood County infestation where eradication efforts are underway. The infestation in Hancock County is probably the result of people moving firewood or logs in violation of quarantine orders. Scouts are exploring Hancock County to determine the extent of the infestation.

PBS show on invasives

Tue, 12 Apr 2005 14:46:02 GMT

PBS has a new National Geographic series, "Strange Days," beginning on April 20. The first episode is about invasive species. There is a lot of useful information available on the show's web site.

Lack of federal support slowing emerald ash borer control

Fri, 08 Apr 2005 16:34:35 GMT

Michigan, which is fighting a losing battle to prevent the spread of emerald ash borer, will have to limit ash tree removal because of a lack of federal funds. The original plan was to remove all ash trees within 1/2 mile of infested trees in seven Michigan counties. The state expected $25 million in federal funds for the project but received only $11 million.

Instead of removing healthy trees around infestations, state officials were only able to remove infested trees and girdle additional trees to create 'traps' for the emerging insects this spring. Creating trap trees could slow the spread of adult beetles, since the preferentially seek out weak trees. However, this is a stopgap measure an will only serve to build up beetle populations over time.

The state is trying to eliminate ash borer infestations at several 'gateway' locations - areas from which the borers could spread to the Upper Peninsula or to Ohio or Indiana to the south and the St. Clair River to the east.

Of course, this strategy assumes that emerald ash borers will spread by themselves. It is much more likely that people moving firewood or logs out of the quarantine area will bring infestations to new locations.

The federal government has increased funding for emerald ash borer control, but the funds are spread between three states (Michigan, Indiana, Ohio) with infestations. Federal funding would need to double to meet the quarantine needs of all three states.