Year: 2017

Oak leaves dropping, but it’s not oak wilt!

Posted on by colleenrobinson
This oak tree near Pelican Lake dropped leaves due to Cylindrosporium both in 2011 and again this year. This will not cause mortality of the tree.

This oak tree near Pelican Lake dropped leaves due to Cylindrosporium both in 2011 and again this year. This will not cause mortality of the tree.

The small round leaf spots characteristic of infection by Cylindrosporium fungi

The small round leaf spots characteristic of infection by Cylindrosporium fungi.

In September and October, I visited several northern red oaks that were dropping leaves, but none of them looked like they had oak wilt. The dropped leaves were still green but had many perfectly round tan dots on their surface. I collected some leaves and sent them into the lab to verify the causal agent. One of these trees had shown similar symptoms in 2011. At that time, Brian Schwingle (who has since taken his forest health skills to the Minnesota DNR) looked at it and diagnosed Cylindrosporium leaf spot. I suspect the same this year. I’ve found trees of all ages with similar leaf spots in Marinette, Oconto, Oneida, Vilas, and Waupaca counties. Impacted trees often dropped some of the infected leaves, although a lot of green leaves (with additional leaf spots) remained on the tree. These trees should leaf out normally next year.

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

Oak skeletonizer showed up late this season

Posted on by colleenrobinson
Oak skeletonizer is a tiny caterpillar that feeds on oak by removing just the lower layers of the leaf, leaving the paper-thin upper epidermal layer.

Oak skeletonizer is a tiny caterpillar that feeds on oak by removing just the lower layers of the leaf, leaving the paper-thin upper epidermal layer.

This is the same leaf as above, just being held up to the sky so you can see how there is one very thin layer of leaf left where oak skeletonizer was feeding.

These two pictures are of the same leaf.  In this photo, the leaf is being held up to light to show how there is one very thin layer of leaf left where oak skeletonizer was feeding.

Oak skeletonizer (Bucculatrix ainsliella) is a native insect that defoliates oak in Wisconsin. Damage was observed in most counties in northeast and central Wisconsin. There are two generations per year. Damage from the first generation this year barely showed up at all, but defoliation by the second generation became quite noticeable in late August and September. Continue reading “Oak skeletonizer showed up late this season” →

Oak bullet gall

Posted on by colleenrobinson
Round hard galls from oak bullet gall wasps can impact growth of young oaks if the population is high enough.

Round hard galls from oak bullet gall wasps can impact growth of young oaks if the population is high enough.

There are a lot of galls on oak. One that can cause some problems at heavy densities is the oak bullet gall. These galls, sometimes called rough bullet galls, can quickly become unsightly. I usually see them on burr oak and occasionally on swamp white oak. They are caused by a gall wasp. The galls start out green-colored, eventually darkening to brown as the season progresses and the gall wasp larvae grow inside. Continue reading “Oak bullet gall” →

Spider mites cause bronzing on oak leaves

Posted on by colleenrobinson
Bronzing along the veins of this oak leaf is due to feeding mites.

Bronzing along the veins of this oak leaf is due to feeding mites.

In August and September, I observed bronzing due to mites feeding on some young swamp white oaks. The tops of the leaves were very bronzed along the main veins, while the undersides of the leaves remained unaffected. When looking at the leaves with my hand lens and under the microscope, I saw a very heavy infestation of mites. Mites suck plant juices from the cells of the leaf.

Continue reading “Spider mites cause bronzing on oak leaves” →

Tiny spikey aphids on maple leaves

Posted on by colleenrobinson
These spikey aphids, marked with blotches of brown and tan, are maple aphids.

These spikey aphids, marked with blotches of brown and tan, are maple aphids.

As I wandered through the woods one day in September, I noticed some spots on a sugar maple leaf. When I flipped it over, I discovered tiny black dots on the underside. They looked like tiny flea beetles to the naked eye (they were very tiny), but I didn’t know of any flea beetles on maple. After putting them under the microscope, I discovered that my tiny bugs weren’t beetles at all, they were maple aphids! They are tiny, dark, and spiky! Cute little suckers! They weren’t doing any significant damage to the leaves that I could tell, although all the leaves in that area had at least a few aphids on the underside. I’ll watch this area next year to see if I can find them again.

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

 

Jumping galls cause defoliation on white oaks

Posted on by colleenrobinson
Brown areas on these white oak leaves were caused by a heavy infestation of jumping oak gall.

Brown areas on these white oak leaves were caused by a heavy infestation of jumping oak gall.

Jumping oak galls caused by tiny wasps form on the underside of white oak leaves.

Jumping oak galls caused by tiny wasps form on the underside of white oak leaves.

If you were in Waupaca County this summer, you probably noticed that large white oaks were looking pretty brown. They were being defoliated by a tiny gall wasp called jumping oak gall (Neuroterus saltatorius). The small galls, which develop around tiny larvae on the undersides of oak leaves, fall off the leaves in late summer. Continue reading “Jumping galls cause defoliation on white oaks” →

Acorn weevils

Posted on by colleenrobinson
The round hole at the edge of the fallen acorn’s cap was created when an acorn weevil larvae chewed its way out to find a place on the ground to overwinter.

The round hole at the edge of the fallen acorn’s cap was created when an acorn weevil larva chewed its way out to find a place on the ground to overwinter.

In some areas of Oconto County, a large percentage of the acorns on northern red oaks dropped early. Most of those acorns were infested with acorn weevil, although at the time they dropped they looked whole. After sitting for a few days, acorn weevil larvae started to emerge in hopes of burrowing into the soil to find a place to spend the winter.

Adult acorn weevils have very long narrow snouts and feed on acorns that are still attached to the tree. They chew a small hole in the acorn, then lay an egg (or several eggs) in the hole. They then plug the hole with fecal pellets, camouflaging their work. The eggs hatch and larvae begin feeding within the acorns. In the fall, the acorn drops to the ground and the larvae chew their way out, after which they bore into the soil to spend the winter underground. There is a different species of acorn weevil that feeds on acorns that have already fallen.

Even though the acorns looked perfect when they dropped, the insects had already been at work on them. Floating acorns in water will allow you to sort out the ones that are damaged, even though you may not see damage on the outside.

Written by: Linda Williams, forest health specialist, Woodruff, (Linda.Williams@wisconsin.gov), 715-356-5211 x232.

 

2017 Urban and Community Forestry Questionaire

Posted on by Ellen Clark

This month, nearly 700 communities across the state will receive a request in the mail to complete a questionnaire for an important project to determine the current management of community tree populations in Wisconsin.  The study is being jointly conducted and sponsored by the University of Wisconsin – Stevens Point, the Wisconsin Department of Natural Resources Urban & Community Forestry Program, and the USDA Forest Service.  It serves to provide important information for the state program since the last community survey in 2008 and as a student project at UW – Stevens Point.

Continue reading “2017 Urban and Community Forestry Questionaire” →

Hoppe Tree Service partners with Brown Deer High School to utilize urban wood

Posted on by Ellen Clark

This fall semester, students at Brown Deer High School won’t have to worry about whether or not they have enough lumber supplies and project ideas to perform during their Industrial Arts Wood Shop classes. This is thanks to a partnership between the school and Hoppe Tree Service.   The partnership centers around the concept of using locally sourced urban wood from Hoppe Tree Service’s Urban Wood Lab Store.  The agreement not only provides lumber for the school, but also allows the student’s non-profit “business” to earn money by processing wood and creating crafts that Hoppe’s Urban Wood Lab Store can then sell to consumers. Continue reading “Hoppe Tree Service partners with Brown Deer High School to utilize urban wood” →

Conversations about the Wisconsin Community Tree Map

Posted on by Ellen Clark

The following article was written by Elizabeth Dierickx, Marketing Specialist at Plan-It Geo, LLC, based on conversations she has had with DNR staff members.

I recently had the pleasure of sitting down with Dan Buckler, DNR Urban Forest Assessment Specialist and Laura Lorentz, DNR Urban Forestry Policy & Partnership Specialist to talk about Wisconsin’s new Community Tree Map. This exciting tool has brought a lot of new excitement and opportunity to the states community forests; the Community Tree Map has the potential to assists the urban forestry team in developing policies based on data driven analysis, has given them a better tool to make recommendations, and helped to create awareness about the urban forest with community members and decision makers. Continue reading “Conversations about the Wisconsin Community Tree Map” →