Disease

Public comment period for HRD treatment guidelines revision closes October 16

A fruiting body of Heterobasidion irregulare at the base of a pine tree.

By Kyoko Scanlon, forest pathologist, Fitchburg. Kyoko.Scanlon@wisconsin.gov; 608-235-7532

Wisconsin DNR is seeking public comments on a proposed revision to preventative treatment guidelines for Heterobasidion root disease (HRD). Stand-level HRD treatment guidelines were originally released in 2013. A DNR technical team and stakeholder advisory committee proposed a revised version using recent research findings, operational experience, and economic considerations.

The draft document and information about the public comment process can be found at  https://dnr.wi.gov/news/input/Guidance.html#open through Tuesday, October 16, 2018. All comments must be submitted by that date.

Leaf-browning on white and burr oaks

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

Dying leaves on white oak. Photo: Mike Hillstrom.

Dying leaves on white oak. Photo: Mike Hillstrom.

During late August and September of this year, Forest Health staff received several comments about problems with white and burr oaks. Leaves on affected trees turned brown, curled and died prematurely. Some trees were almost completely affected, while others only mildly. Symptoms varied widely between trees, even between those located next to each other. After examining several samples, the DNR Forest Health Lab concluded that damage was likely caused by fungal leaf pathogens and the twig canker fungus Botryosphaeria. Because the damage occurred late in the growing season, afflicted trees will not likely suffer major impacts. Although Botryosphaeria can cause twig dieback, oak trees usually recover without long-term problems. Continue reading “Leaf-browning on white and burr oaks”

Spruce needle rust not an issue this year

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

Orange fruiting bodies of spruce needle rust erupt from needles. From a distance, the tree appears orange due to colored pustules on the needles. Photo: Linda Williams

Orange fruiting bodies of spruce needle rust erupt from needles. From a distance, the tree appears orange due to colored pustules on the needles. Photo: Linda Williams

Occurrences of spruce needle rust in northeastern and north central Wisconsin is low this year for the first time since 2013. Spruce needle rust, caused by the fungus Chrysomyxa weirii, infects spruce needles. Fruiting structures erupt from needles in August in shades of pink, yellow, and orange, greatly affecting the appearance of the trees. In addition, infected needles drop off, causing trees to look sparse.

No treatments are available for already-infected needles. Preventative fungicide treatments for yard trees may be used the following spring and early summer, but treatments must be applied before symptoms appear. Repeated treatments will be necessary; the fungicide, which must fully coat needles to be effective, washes or wears off over time.

Widespread crown dieback and delayed leaf-out of bur oak

by Paul Cigan, forest health specialist, Hayward, Paul.Cigan@wisconsin.gov. 715-416-4920 and Todd Lanigan, forest health specialist, Eau Claire, Todd.Lanigan@wisconsin.gov, 715-210-0150

Typical appearance of bur oak with crown dieback associated with cynipid gall wasp infestation in northwest WI during early summer, 2018.

Bur oak showing moderate crown dieback. Photo: Paul Cigan

Bur oak with heavy crown dieback and delayed leaf flushing in Polk County.

Bur oak with severe crown dieback. Photo: Paul Heimstead

Widespread dieback of twigs and branches and delayed leaf-out were present on bur oak trees this spring in Barron, Burnett, Chippewa, Eau Claire Polk, Rusk, and Sawyer counties, and in parts of central and east central Minnesota. Crown dieback of between 10 – 50% was observed in both mature and sapling-sized trees, although it was more common on open-grown trees and those along woodland edges. Tufted or “broomed” leaf shoots were apparent, a result of epicormic shoots developing below dead twigs and branches. Most impacted trees recovered well by early July as crowns filled in with leaves and epicormic shoots. Leaves in recovered trees appeared generally healthy and normal-sized.

Continue reading “Widespread crown dieback and delayed leaf-out of bur oak”

Be on the lookout for beech leaf disease

By Kyoko Scanlon, forest pathologist, Fitchburg. Kyoko.Scanlon@wisconsin.gov; 608-235-7532

Early striping from BLD as seen looking up into the canopy. Photo: The Ohio State University.

Early striping from BLD as seen looking up into the canopy. Photo: The Ohio State University.

Although beech leaf disease (BLD) has not been found in Wisconsin, forest owners and managers should keep an eye out for it on American (Fagus grandifolia) and, to a lesser extent, European (Fagus sylvatica) beech trees. Beech leaf disease is becoming a serious issue in parts of Ohio, West Virginia, Pennsylvania, New York and Ontario. Its cause is not yet known.

Continue reading “Be on the lookout for beech leaf disease”

Balsam fir mortality in many counties around the state

Counties shaded in blue are where balsam mortality has been reported, but the is even more widespread than this map indicates.

Counties shaded in blue are where balsam mortality has been reported, but it is even more widespread than this map indicates.

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

Reports of balsam fir suddenly turning rusty red to brown and dying have been coming in steadily this spring and summer. The accompanying map shows where this has been reported so far this year.

Spoiler alert! There are no insect or diseases involved. It appears the cause may be unusually severe winter drying or winter damage.

Continue reading “Balsam fir mortality in many counties around the state”

White pine bast scale and fungus

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

Branches in the mid- and lower-crown of this white pine are being killed by white pine bast scale and a fungal disease.

Branches in the mid- and lower-crown of this white pine are being killed by white pine bast scale and a fungal disease. Photo: Linda Williams

White pine bast scale and canker fungus has been identified in two sites in Oneida County. This insect/fungus complex is a new issue in the state; those who work with white pine should be alert for signs and symptoms.

White pine bast scale, a native scale, is tiny, black, oval-shaped, and lacks both eyes and legs. It uses a long stylet to siphon sap from outer layers of phloem (bast) of twigs and branches. White pine bast scales live under lichens on white pine branches. Although lichens don’t directly harm trees, they provide shelter for scale insects.

Continue reading “White pine bast scale and fungus”

Region-wide needle tip browning on red pine

Typical appearance of needle tip browning on lower portion of red pine crowns

Red pine with needle tip browning on the lower crown. Photo: Paul Cigan

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

Although no tree mortality is associated with the condition, widespread needle tip browning on red pine has been observed for the second consecutive year across much of the upper Great Lakes region. The condition is heavier in some places than others, but once in a stand or location, tends to be evenly distributed. Needle tip browning is common on the lower half of mature red pine crowns. On two- to three-year-old needles, the outer half to three-quarters of the needles appear reddish brown to straw-colored while needle bases remain green. Black or dark brown necrotic bands and spots are often present on symptomatic needle tips. Lower crown thinning is also common on symptomatic pine. Newly impacted needles will gradually lighten in color from reddish brown to straw-colored as dead needle tips dry out through the growing season. Continue reading “Region-wide needle tip browning on red pine”

Rhizosphaera needle cast disease on spruce

Spruce trees affected by rhizosphaera needle cast disease will have thin foliage in the lower parts of the tree, and branches may die in severe cases. Some trees are more susceptible, like the tree on the far left and the tree on the far right.

Spruce trees affected by rhizosphaera needle cast disease will have thin foliage in the lower parts of the tree, and branches may die in severe cases. Some trees are more susceptible, like the tree on the far left and the tree on the far right. Photo: Bethany and J.R. Pulham

By Linda Williams, forest health specialist, Woodruff.  Linda.Williams@wisconsin.gov; 715-356-5211 x232

 Are the lower branches of your spruce tree suddenly looking very thin? Rhizosphaera needle cast disease, caused by a fungal pathogen, can severely impact spruce, killing needles and causing them to drop prematurely. Wet years such as 2017 are great for the fungus, but bad for trees. Spring 2016 was also unusually wet, allowing the fungus to start to build up. With all the rain and wet conditions of 2017, the disease exploded. Continue reading “Rhizosphaera needle cast disease on spruce”

New “Tick App” available

Ticks pose increasing health threats throughout North America

Ticks pose increasing health threats throughout North America. Photo: WI DNR

from the May 2018 edition of RECReport, for the WI DNR Bureau of Parks and Recreation Management

The University of Wisconsin-Madison, a partner in the Midwest Center of Excellence (Center) in Vector-Borne Diseases, has announced that “Tick App” is now available for download. Tick App is a phone application that is part research tool and part educational tool with the goal to transition towards a preventative tool over time.

The Center would like to enroll people, by the app, in their study to determine the risk for tick encounters, assess the success/failure of self-reported prevention strategies, and educate people at the same time. Participation is entirely voluntary. When people download the app, they will go through a sign-up process—and about 5 minutes of questions—so the researchers can assess risk factors for tick exposure.

When people are in the app they can complete daily tick diaries (asking about activities and tick exposure) and can report a tick. Users can even send in an image for identification after the report is completed. For more information on the Tick App, visit http://www.thetickapp.org or tickapp@wisc.edu.