Forest Health News

Heavy seed crop leads to sparse-looking trees

Posted on by margueriterapp

Todd Lanigan, forest health specialist, Eau Claire, Todd.Lanigan@wisconsin.gov, 715-839-1632

You may have noticed some of the elms and maples had a lot of brown in them at the end of May and early June. Some elms and maples produced a lot of seed this spring, which reduced the amount of energy available for producing leaves. With fewer leaves and more of the brown, papery seeds, the trees can take on a thin, brown appearance.

Heavy seed years can occur for many reasons. It happens naturally from time to time and it can also be stimulated by environmental stressors. A couple of examples of environmental stressors are: excessive moisture, winter injury and frost damage to roots.

The cause of this year’s heavy seed production is anyone’s guess. There does not appear to be a common pattern between the affected trees to indicate whether it was simply a normal heavy seed year or related to an environmental factor.

 

Browning on tamarack needles

Posted on by margueriterapp

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

Defoliation from larch casebearer (Coleophora laricella) is showing up in some areas of northeast and northcentral Wisconsin. The defoliation is patchy and of moderate intensity, resulting in trees with various degrees of browning due to the insect’s feeding habits. Some appear pale yellow or brown throughout the crown while others only have partial browning.

Defoliated larch needles turn yellow then brown.

Defoliation by larch casebearer will cause needles to turn yellow then brown. Trees will usually send out more needles and be green again by mid-summer.

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Branch flagging caused by jack pine resin midge

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

Jack pine shoots are flagging over a large area of northern and west central Wisconsin this summer due to feeding injury from the jack pine resin midge. Symptoms include scattered dead branch tips and pitch masses on terminal buds and on twigs where larvae feed.  

Jack pine with dead branch tips caused by jack pine resin midge. Photo: Paul Cigan.

Jack pine with dead branch tips. Photo: Paul Cigan.

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Native caterpillars not a major concern for trees

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Mike Hillstrom, forest health specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov, 608-513-7690

Eastern tent caterpillars (ETC) are hatching and beginning to feed on host trees, including cherry, apple and crabapple. Landowners and homeowners may notice the white silken tents forming in branch forks. Although they form unsightly tents, ETC is a native insect so management is not typically necessary. Even completely defoliated trees will put out new leaves within a few weeks.

A group of eastern tent caterpillars warm themselves on white silk tent before leaving to feed on black cherry leaves.

If landowners want to remove the tents the best time to do so is early morning or evening when the caterpillars are inside. Unless it is raining, eastern tent caterpillars leave their tents each morning to feed throughout the day before returning at night. Caterpillars can be removed either by hand if they are within reach or with a rake if they are high in the tree. They can then be killed by soaking them in soapy water or sealing them in a trash bag. Insecticides are rarely necessary but should penetrate inside the tent if used. Do not prune branches, burn tents or soak them with WD-40. These methods are more harmful to the tree than ETC defoliation and are not recommended.

For more information on eastern tent caterpillar, read this factsheet from UW-Madison Division of Extension.

Protect yourself from ticks and tickborne illnesses

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Bill McNee, forest health specialist, Oshkosh, Bill.McNee@wisconsin.gov or 920-360-0942

Adult deer tick. Credit: Scott Bauer, USDA Agricultural Research Service, bugwood.org.

So far this spring we are off to a busy tick season, with many reports and photos being sent in to DNR staff. Ticks can be found year-round in Wisconsin but are most active from May to September. Some species, including the deer tick responsible for Lyme disease, carry infectious diseases that elevate them from mere nuisance to serious health threat.  Lyme disease is most often spread by very small, immature ticks known as “nymphs.” Adult deer ticks can also transmit Lyme disease, but because they are larger, they are more likely to be discovered and removed compared to the tiny nymphs which can be as small as a chia or sesame seed.

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Needle and leaf diseases are back!

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Mike Hillstrom, forest health specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov, 608-513-7690

It’s nearly summer and the usual cast of disease characters are on the scene following wet spring conditions. Rhizosphaera needlecast and other needle diseases impacting spruce continue to be a major concern for landowners and homeowners. Diseases in hardwoods are also popping up. For more information on needle and leaf diseases affecting trees in Wisconsin and resources to learn more, click below to read full article. 

A row of spruce trees with dead branches and missing needles caused by Rhizosphaera needlecast.

Spruce trees impacted by Rhizosphaera needlecast.

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Branch tips littering the ground under your trees?

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

Have you been noticing branch tips scattered on the ground beneath spruce, fir or pine trees this spring? You may be seeing one of a few things – damage from small animals or breakage caused by the harsh winter we had. Fortunately, the damage from either is unlikely to do serious harm to your trees. 

Spruce branch tips found on ground were clipped from tree by squirrels.

Spruce branch tips found on ground were clipped from tree by squirrels.

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Educational EAB DVDs available for order

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Educational EAB DVDs.

Marguerite Rapp, communications and education/outreach specialist, Madison, Marguerite.Rapp@wisconsin.gov, 608-843-3506

The Forest Health Program has educational DVDs on the emerald ash borer (EAB) available for order. Produced in 2010 by the Wisconsin Cooperative EAB Program, the DVDs contain three videos to help viewers identify emerald ash borer, ash trees and signs of infestation. Each video is between 3-6 minutes in length.

If you would like free copies of this DVD for yourself or to share with partners and organizations in your community, please send an email to Marguerite.Rapp@wisconsin.gov that includes your name, mailing address and total number of copies needed. Please share this offer with anyone who may be interested.

Northwestern county forests trap for EAB

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

Several forestry partners will be trapping EAB in the northern region in 2018 using baited prism traps similar to this one.

EAB purple prism trap in ash tree.

A number of county forestry partners in northwest Wisconsin are trapping for emerald ash borer (EAB) on their properties this year with technical assistance from the DNR forest health team. Potential captures of EAB may give officials a better understanding of the invasive beetle’s distribution in the region that can support forest management planning and public awareness. Partners conducting trapping include Bayfield, Douglas, Rusk, Sawyer counties and the Barron County Conservation District. Landowners and property managers are encouraged to report signs and symptoms of EAB activity to their regional forest health specialist.

Learn more about emerald ash borer and signs/symptoms of infestation at the DNR emerald ash borer page.

Another low year for forest tent caterpillar

Posted on by margueriterapp

Paul Cigan, forest health specialist, Hayward, Paul.Cigan@wisconsin.gov, 715-416-4920 and Linda Williams, forest health specialist, Woodruff, Linda.Williams@wisconsin.gov, 920-360-0665

Newly hatched forest tent caterpillars on egg mass.

Forest tent caterpillar larvae emerging from egg mass.

Forest tent caterpillar egg surveys conducted in northern counties indicate hardwood defoliation from this native insect will remain low in 2019, sustaining a 16-year trend. The last FTC outbreak affected northern Wisconsin from 1999 – 2002. Cooler and wetter than average spring weather may indirectly reduce caterpillar populations by enhancing the activity of pathogenic fungi. Please report any possible defoliation to your regional forest health specialist.

To learn more about this insect, visit the DNR forest tent caterpillar webpage.