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Tag Archive | "Oak wilt"

Oak Wilt


Ranger Steve Mueller

Ranger Steve Mueller

By Ranger Steve Mueller

 

Oak wilt can impact your home cooling when shade trees die by exposing the house to heat from the summer sun. The beauty of the yard, as well as a multitude of valuable wild neighbors surrounding your family, will disappear with an oak’s death. Prevention of oak wilt disease infection is important.

The spread of the disease can be most prevalent where new home construction occurs. Once the disease becomes established it is expensive to treat in both money and environment altering impacts.

Oak wilt is a fungal infection that clogs sapwood under the bark of oak trees. Trees ship water and nutrients upward through straw-like tubes called xylem. When the tubes become clogged and flow is stopped, the tree cannot survive. An infected tree can die within weeks. Think about it like very rapid coronary occlusion where blood can no longer supply your heart. The heart will cease to function and your entire body dies.

When water and nutrients are no longer transported throughout the tree, the leaves wilt, growing stems die, and the entire tree succumbs. Some oak species are more susceptible. The red oak group is at highest risk. The white oak group roots do not graft as extensively as red oaks and they have little plugs in their sapwood that slow the spread of fungus growth.

Grafting is common where roots overlap. You might be familiar with fruit tree grafting where a favorite apple variety can be grown on another apple tree by taking a cutting from a favored variety twig, remove a similar sized piece on another apple tree, insert the favored twig, and seal around the surgical implant. That might be an oversimplification but it is the basic process.

Where small oak roots come in contact, the thin outer bark between two roots wears and the inner tissues become interconnected. Once connected bark healing encases them together and material can flow from tree to tree. They are not Siamese twins but physiologically they are attached in a similar manner. They can be separated and it might be essential to stop the spread of oak wilt from progressing through an entire forest.

Forest treatment is expensive so prevention is the most important practice. Treatment is not detailed here.

From April Fool’s Day to the 4th of July is when it is important to prevent oak trees from experiencing open sores. Do not prune branches on oak species or cut down trees during that time. Notice oaks are specified. The fungus Ceratocystis fagacearum is the culprit killing agent. It is oak specific and can spread by two methods. One is from tree to tree through the root grafts referred to as “underground spread.”

The other is by “overland spread”. When tree bark is wounded by cutting branches, it allows sap to flow out and attracts tiny sap-feeding Nitudulid beetles that come to feast on the sweet-smelling sap. Infected trees have fungus blisters that produce spores that get on the bodies of the beetles. When the insect travels to a freshly wounded tree, the fungus is transferred and begins growth.

The adult beetles are active from early spring to the 4th of July. Completing tree and branch cutting by March and not resuming until July is important to prevent the spread of the disease.

During my forestry training I learned painting wounds with pruning sealer tree paint was not particularly important and was an unnecessary expense. Not all foresters agreed. Today applying it has become important to prevent beetle access to save oaks and should be used immediately when a tree is cut down or branches are cut.

Little things like where you place bird feeders is important. Chickadees and titmice take seeds to branches in their nature niche to peck sunflower seed hulls. In the process, they create small openings in branch bark that exposes sapwood to infection. Place feeders on other tree species or use shepherd hooks away from oaks.

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.

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State urges travelers to leave firewood at home


Perfectly round exit holes, just smaller than a dime, in tree limbs and trunks can be a sign of Asian longhorned beetle infestation. Photo courtesy of Joe Boggs, Ohio State University, Bugwood.org.

Perfectly round exit holes, just smaller than a dime, in tree limbs and trunks can be a sign of Asian longhorned beetle infestation. Photo courtesy of Joe Boggs, Ohio State University, Bugwood.org.

As the summer travel season begins, the Michigan departments of Agriculture and Rural Development and Natural Resources remind vacationers to leave firewood at home to prevent the spread of invasive tree insects and diseases.

Hauling firewood from one part of the state to another is a common way for these destructive pests to move to new locations, which could be devastating to Michigan’s native trees. The emerald ash borer already has wiped out millions of ash trees across the state. High-impact diseases, including oak wilt and beech bark disease, now are making their way through Michigan – often helped by travelers with trunkloads of wood harboring unseen fungi that can spread to healthy trees in new areas.

The fungus that causes oak wilt is visible under the bark of this split log.

The fungus that causes oak wilt is visible under the bark of this split log.

“Visual inspection does not always reveal disease or insect damage in wood,” said Gina Alessandri, MDARD’s Pesticide and Plant Pest Management Division director. “Disease may be in an early stage, and insect larvae can be hidden under bark. The safest choice is to burn firewood at or near the location it was harvested.”

Travelers are encouraged to buy firewood at their destination, burn it all on-site and not take it home or to their next destination. In most public and private campgrounds, firewood is available on the premises or from nearby firewood vendors.

It is a good idea to purchase firewood within a short distance of where it will be used. For ease in finding a local vendor, use www.firewoodscout.org. For day trips that include a cookout, bring charcoal or a cook-stove instead of firewood.

In- and out-of-state quarantines limit movement of regulated wood items to prevent the spread of invasive species and tree diseases. In Michigan, it is illegal to transport hardwood firewood in violation of the MDARD EAB Quarantine.

“It’s recommended that travelers do a little firewood homework before their trip,” said Jason Fleming, chief of the Resource Management Section in the DNR Parks and Recreation Division. “Many out-of-state visitors live in areas under quarantine for pests such as thousand cankers disease or Asian longhorned beetle, and it is illegal to move any regulated items (including items such as firewood and wood chips) from quarantined zones out of those states and into Michigan.”

Quarantines for Asian longhorned beetle include areas of New York, Massachusetts and Ohio. The Asian longhorned beetle is not known to be in Michigan, but the public is asked to look for signs of this invasive beetle, including round, 3/8-inch-diameter exit holes in tree trunks or limbs. Asian longhorned beetle larvae feed on a wide variety of tree species including maple, birch, elm, willow, buckeye, horse chestnut and other hardwoods. The damage caused by Asian longhorned beetles ultimately will destroy an infested tree.

Anyone observing an actual beetle or a tree that appears to be damaged is asked to report it. If possible, capture the beetle in a jar, take photos, record the location, and report it as soon as possible through the U.S. Department of Agriculture’s Asian longhorned beetle website, www.asianlonghornedbeetle.com or contact MDARD at 800-292-3939 or MDA-info@michigan.gov.

More information on the Asian longhorned beetle and other invasive forest insects and tree diseases can be found at www.michigan.gov/invasivespecies. Select the “take action” tab to learn more ways to avoid transporting invasive species during the recreation and travel season.

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Do not move firewood between state parks 


Lethal tree infection caused by transport of firewood

OUT-Oak-wilt

Oak wilt outbreaks are increasing in Michigan and the Department of Natural Resources has conducted treatment at several state parks to halt the spread of the disease.

Oak wilt is an introduced disease that causes rapid death of infected trees. The fungus is easily transported by beetles from infected wood to nearby wounded trees. Trees cannot be cured of oak wilt, and once a tree is infected the disease can rapidly spread to neighboring trees through underground root graft connections. The loss of large numbers of oak trees in parks can be dramatic, both for the park visitor experience and the ecology of the natural habitat.

“The likely cause of the oak wilt outbreak at Michigan state parks is the movement of infected firewood into campgrounds,” said DNR natural resources steward Heidi Frei. “Campers and other park visitors can help prevent the spread of the oak wilt fungus by not moving firewood between campgrounds.”

DNR Parks and Recreation Division staff has been working the last several years to stop the spread of oak wilt at Michigan state parks throughout the state, including P.J. Hoffmaster, Otsego Lake, Interlochen, Warren Dunes and Hartwick Pines state parks; and Fort Custer, Rifle River, Waterloo, Brighton, Pinckney and Island Lake recreation areas.

Treatments in 2014 included using a vibratory plow fitted with a special blade (designed and fabricated at the DNR’s Forest Fire Experiment Station in Roscommon) that severs grafted tree roots, isolating healthy trees from infected trees. Treatment also included the application of fungistats, which inhibit the growth and reproduction of fungi, and which have been used in areas declared critical dune habitat.
“If left unchecked,” Frei said, “oak wilt will continue to spread and result in large pockets of standing dead oak trees, which may be hazardous to park visitors.” Some parks, such as P.J. Hoffmaster, have experienced considerable losses. More than 100 large red oaks, including the most picturesque grove of red oaks in the campground, have been killed by oak wilt.
For more information on oak wilt prevention and stewardship, visit www.michigan.gov/foresthealth or contact Heidi Frei at 517-202-1360 or freih@michigan.gov.

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