Insect

Prepare for the return of gypsy moths in spring

Posted on March 30, 2020April 20, 2020 by margueriterapp

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.

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Where are you, blue ash?

Posted on February 25, 2020February 25, 2020 by patricialindquist

By Dan Buckler, DNR urban forestry assessment outreach specialist, Madison, Daniel.Buckler@wisconsin.gov, 608-445-4578

It is no secret that the emerald ash borer (EAB) has a voracious appetite. This pest has eradicated unprotected green and white ash in many communities in southern Wisconsin and can be expected to eventually impact all communities in the state. EAB is also damaging wetland and riverine forests by eliminating green and black ash from these woodlands, which had already become less diverse and resilient from the loss of American elm from Dutch elm disease.

While EAB can feed on all American ash species so far tested, some are less favored than others and thus take less damage from the pest. Reduced feeding pressure may allow such species to persist in the presence of EAB. Blue ash (Fraxinus quadrangulata) is one of these less preferred hosts of EAB. This tree, a native of the Midwest and South, enjoys calcareous soils and has been found growing naturally in southeast Wisconsin. Even before EAB, it was considered a Threatened plant in the state, though it is common in states to the south of us. It’s an unusual tree but some communities and individuals have planted blue ash across the state.

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Wisconsin DNR Forest Health 2019 Annual Report

Posted on February 25, 2020February 25, 2020 by patricialindquist

The DNR Forest Health team recently completed the 2019 Forest Health Annual Report summarizing impacts from pests, diseases and weather on the health of Wisconsin’s forests. Highlights from 2019 include:

• Dramatically increased decline and mortality from EAB in southern WI

• New county and township detections of oak wilt

• Record-breaking precipitation and major storm damage

• Summary of state nursery studies

To read the report, follow this link.

Fighting invasives together through responsible firewood practices

Posted on February 17, 2020March 23, 2020 by margueriterapp

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

Posted on January 30, 2020February 25, 2020 by margueriterapp

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

Posted on January 6, 2020July 15, 2022 by margueriterapp

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.

2019 Forest Health Annual Report now available

Posted on January 6, 2020January 6, 2020 by margueriterapp

Forest health annual report now available for 2019.

The Forest Health Annual Report summarizes notable impacts for that year of pests, diseases and weather on the health of Wisconsin’s forests. The report is a collaborative product created by DNR forest health specialists from around the state. It outlines the damage and spread of both native and invasive pests and diseases during that year and puts these into context of observations from previous years. Management programs and their results are also described. Highlights from the 2019 annual report include:

Dramatically increased decline and mortality from emerald ash borer in southern WI
New county and township detections of oak wilt
Precipitation record and major storm damage
Summary of state nursery studies on Diplodia sapinea, galls on jack pine seedlings, and testing new fumigants to replace methyl bromide

This year’s annual report is available on the DNR forest health homepage. Previous annual reports, including historical reports dating back to 1951, are archived and available upon request. Contact your local forest health specialist if you’d like digital copies of any archived annual reports.

Snow fleas spring to surface in early December

Posted on January 6, 2020January 7, 2020 by margueriterapp

By Todd Lanigan, forest health specialist, Eau Claire. todd.lanigan@wisconsin.gov; 715-210-0150

Snow fleas are a species of springtails that are active during winter and are generally found in groups where their dark-colored bodies stand out against the white snow. While often observed in late winter or early spring, they also come to the surface on warm winter days, making an early December appearance in west central Wisconsin something to note but not altogether unusual given the relatively warm weather in the area.

Tiny flecks against an impression in snow are hundreds of snow fleas at surface.

Easily mistaken for specks of dirt or debris, snow fleas are tiny soil-dwelling animals that gather on the surface of snow on warm winter and spring days.

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New map illustrates damage from EAB

Posted on December 2, 2019December 2, 2019 by margueriterapp

Forest health staff recently produced a map that highlights a gradient of damage from southeastern to northwestern Wisconsin, which roughly corresponds to the length of time EAB has been present in these parts of the state. Whatever the level of damage, homeowners and landowners should consider treating healthy ash, including trees that have responded well to previous treatments, or removing declining, untreated ash before they become hazardous and even more costly to remove.

County-level map of damage from EAB to ash tree populations in 2019

County-level assessment of damage to ash population by emerald ash borer, 2019.

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Invasive plants, ticks and you