South Central WI Forest Health

White pine blister rust can girdle branches

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By Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665

White pine branches that suddenly turn red may be a sign of white pine blister rust. White pine blister rust is a fungal infection that creates expanding “dead spots” or cankers on the branches or main stem of host trees. Eventually the fungus grows enough to girdle the branch or main stem and the needles fade from green to pale green to rusty red. Orange, spore-producing pustules erupt around the edges of the canker in the spring.

Orange pustules erupt through the bark and around the margins of a white pine blister rust canker. Photo by Jean Romback-Bartels.

Orange pustules erupt through the bark and around the margins of a white pine blister rust canker. Photo by Jean Romback-Bartels.

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Gypsy moth spray program begins in May

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The 2020 gypsy moth slow-the-spread program, operated by the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) is expected to begin aerial spraying in the second half of May to slow the westward spread of gypsy moth.

Map of counties to be sprayed in 2020.

Map of counties where slow-the-spread treatments will occur in 2020.

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Protect oak trees by pruning after July, not before

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By Don Kissinger, urban forester, 715-348-5746, Don.Kissinger@wisconsin.gov or Paul Cigan, plant pest and disease specialist, 715-416-4920, Paul.Cigan@wisconsin.gov

Anyone with oak trees in their yards or on forested lands should avoid pruning or cutting them from April through July to protect them from oak wilt.

Sap-feeding beetle on diseased oak tree in Sawyer County.

Sap-feeding beetle on diseased oak tree in Sawyer County.

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Severe spruce needle diseases expected in 2020

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By Bill McNee, DNR forest health specialist, Oshkosh, bill.mcnee@wisconsin.gov, 920-360-0942

Wet weather in 2019 created ideal conditions for Rhizosphaera kalkhoffii and other needle cast fungi to infect spruce needles. Since it takes about a year for the needles to show symptoms, heavy and widespread needle diseases are expected to be seen on spruce trees in 2020. 

Lower branches of an infected spruce tree have lots of missing needles and some that are browning.

Loss of older needles on an infected spruce.

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Prepare for the return of gypsy moths in spring

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By Bill McNee, DNR forest health specialist, Oshkosh, bill.mcnee@wisconsin.gov, 920-360-0942

Gypsy moth eggs are expected to start hatching as temperatures warm in the next few weeks. Now is a great time for homeowners to check their trees for egg masses and treat or remove any that are found. Removing the egg masses now will help protect trees from defoliation and reduce future caterpillar populations.

Gypsy moth larvae hatching from egg masses on an outdoor bowl.

Gypsy moth larvae hatching from egg masses on an outdoor bowl.

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Nominations Open For “Invader Crusader” Awards

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By Tara Bergeson, DNR invasive species team leader, 608-264-6043, Tara.Bergeson@wisconsin.gov

Nominations are being accepted through March 23, 2020 for “Invader Crusaders.” These awards go to individuals, groups and organizations who made outstanding contributions in 2019 to prevent, control or eradicate invasive species that harm Wisconsin’s native wildlife and wetlands, forests, prairies, lakes and rivers.

The Wisconsin Invasive Species Council is seeking nominations for exemplary efforts at addressing issues surrounding terrestrial and aquatic invasive plants and animals. The awards will be presented in both volunteer and professional categories.

To submit a nomination, download and fill out a nomination form available on the Wisconsin Invasive Species Council’s Invader Crusader webpage. Email the completed form to invasive.species@wisconsin.gov by March 23.

A panel of Wisconsin Invasive Species Council members will review the nomination materials and select the award winners. All nominators and winners will be notified by mid-May 2020.

Recipients of the awards will be recognized at an awards ceremony on June 11 at Olbrich Botanical Gardens in Madison.

Invasive species are nonnative plants and animals that cause great ecological, environmental or economic harm, and some can even affect human health. Once an invasive species becomes established in an area, it can be difficult to control. The most important action Wisconsinites should take is to avoid moving invasive species or the materials that might harbor them to new places.

To learn more about what you can do to stop the spread of invasive species, visit the DNR invasive species webpage.

Fighting invasives together through responsible firewood practices

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By Marguerite Rapp, forest health communications specialist, marguerite.rapp@wisconsin.gov, Andrea Diss Torrance, invasive insects program coordinator, andrea.disstorrance@wisconsin.gov, and Tim Allen, DATCP forest pest program coordinator and nursery inspector, timothy.allen@wisconsin.gov, 715-891-8158

This time of year, many Wisconsinites warm up with firewood, whether that’s in a wood stove for the home or a bonfire with family and friends. While firewood is one of the most sustainable heat sources available, the forests that produce it are threatened when firewood infested by invasive species is moved long distances. Fortunately, we can reduce this threat together through responsible use, movement and sale of firewood and wood products.

Man loads firewood into arms from back of truck. Continue reading “Fighting invasives together through responsible firewood practices” →

Check your trees for EAB and plan for spring

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By Bill McNee, forest health specialist, Oshkosh, bill.mcnee@wisconsin.gov, 920-360-0942

The cold winter months are a great time to think about emerald ash borer and whether ash trees in your yard are suitable for treatment. The pest is currently the most damaging threat to trees in Wisconsin, killing more than 99 percent of the ash trees it infests.

Two side-by-side images depicting different stages of flecking on ash trees - on left side is light flecking in the upper canopy of a tree, on the right side is more severe flecking that extends down the trunk of the tree

Woodpecker flecking is an early sign of EAB infestation when it appears in the tops of trees (left). As the infestation progresses, flecking continues down the trunk and into lower parts of the crown (right).

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Upcoming forest health events

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Learn more about forestry and forest health issues with these upcoming events in February and March! We link to conference brochures and webpages where you can find detailed information, including registration prices and deadlines where applicable. Continue reading “Upcoming forest health events” →

Protect your trees from disease by pruning when they have no leaves

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By Paul Cigan, forest health specialist, Hayward, paul.cigan@wisconsin.gov, 715-416-4920

With the new year upon us, healthy lifestyle habits are sure to be on many people’s minds as they plan for changes in diet and exercise. The new year is also the perfect opportunity to make healthier choices for trees! Winter is the ideal time for tree pruning while avoiding harmful, disease-carrying pests such as the tiny beetles that carry oak wilt from one tree wound to another.

“The best time to prune trees that lose their leaves is during winter when the trees are dormant,” said DNR forest health specialist Paul Cigan. “Not only is it easier to see where pruning is needed when leaves are gone, but disease-carrying pests are inactive due to the cold, making pruning both more effective and less likely to invite unwanted pests.”

While pruning in winter reduces the risk of spread through beetles, Cigan pointed out that the disease can spread year-round in firewood. “Several recent oak wilt finds in northern Wisconsin, including a first-ever find in Forest County, may have been the result of infected firewood brought from areas with oak wilt,” Cigan said. “Keep oak firewood where it is cut for one year, or until the bark is naturally loose, to prevent the spread of oak wilt,” he advised.

For more information, visit DNR webpages for oak wilt and firewood.

Pruning tips

Yard trees and trees in urban settings should be pruned throughout their entire life to maintain strong structure and remove dead wood. Young trees should be pruned to establish a central trunk, proper trunk taper and good branch structure and spacing. Older trees should be pruned to remove dead and/or hazardous limbs. “Pruning should not remove more than 25 percent of the live tree crown, and the lower third of deciduous tree trunks should be free of limbs,” advised DNR urban forestry coordinator Don Kissinger. You can find more detailed, step-by-step tips for tree pruning in this DNR tree pruning publication. 

Certified arborists who offer pruning and other tree care services can be found at waa-isa.org/arborists/search.asp.