Author: colleenrobinson

Six new counties quarantined for EAB

Since the August newsletter, it was announced that six new counties would be quarantined for emerald ash borer (EAB). The find in Chippewa County was due to a vigilant landowner while the other finds were due to trapping by USDA APHIS.

Wisconsin counties quarantined for EAB (WI DATCP)

WI counties quarantined for EAB  (DATCP). Most of Wisconsin is EAB-free, including most of the northern half and the yellow areas in all
quarantined counties. EAB has been confirmed only in those cities, villages and townships
colored dark green.

Continue reading “Six new counties quarantined for EAB”

Look for next year’s gypsy moth infestations

Gypsy moth egg mass.

Gypsy moth egg mass

Early fall is the best time for property owners to determine whether gypsy moths will be a problem next year. Gypsy moth egg masses are tan-colored and about the size of a nickel or quarter. Egg masses will not hatch until next spring, which means landowners have plenty of time to plan to minimize gypsy moth damage next summer. New egg masses produced this year feel hard, whereas those that are older are soft and appear faded. Most egg masses will be found on tree trunks and the undersides of branches, but they can also be found on buildings, firewood piles, vehicles and other outdoor objects. 

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New video on buckthorn control available

Common buckthorns retain leaves late into the fall.

Common buckthorns retain leaves late into the fall.

The following article offers a glimpse of the good work that happens after DNR awards grants through its Weed Management Area – Private Forest Grant Program (WMA-PFGP).  Dick Ballou, the driving force of the Cedar Lake Buckthorn Project, takes us through his efforts to raise awareness of that forest scourge -common buckthorn- and control its spread.  The next application deadline for WMA-PGRP grants is April 1, 2018.  More information on applying for the grant can be found here.

Imagine the frustration of eagerly awaiting your opening day of deer hunting, having your stand in a perfect location and learning at daybreak that the woods around your stand are not as you expected? Several years ago, I prepared for bow hunting and found a perfect location for the deer stand, except for one small problem, a 20-foot tall tree full of leaves. Thinking the tree’s leaves would be gone by mid-October, I placed the stand nearby and went home. Returning in October, the “perfect” location was seriously compromised by the same tree – full of leaves – obstructing my view. Later, I learned the tree was invasive common buckthorn that currently threatens woodlots from New England to Wisconsin and beyond. This experience led me to start the Cedar Lake Buckthorn Project and create this video on buckthorn control. Continue reading “New video on buckthorn control available”

Winged ants

A mass emergence of winged ants. Large ones are unmated females and smaller ones are males. They will fly off to mate and start their own colonies. Photo by Mike Kamke.

A mass emergence of winged ants.  Photo by Mike Kamke.

On August 29, and again in early September, a mass emergence of winged ants occurred in southern Vilas County and some areas of northern Oneida County. Mass emergences of winged adults are part of a reproductive strategy used by ants to overwhelm predators, in the hope that a few of the new queens will mate and establish their own nests. When weather conditions are right, winged individuals from many ant colonies in an area will emerge and fly away to mate and start their own nests.

Winged ants consist of large winged females and smaller winged males, but many folks that reported these insects were concerned that they were seeing swarms of wasps since most people aren’t accustomed to seeing ants with wings. Once new queens and males fly away from the nest, they will eventually drop to the ground, shed their wings, mate and start a new nest. These events are relatively rare for folks to see as they are very short lived, with the winged ants generally being gone within a day.

Oak wilt continues to be found in the north

In this photo two oak trees have died from oak wilt (yellow dots). One tree is currently wilting and dropping its leaves (purple dot).

In this photo two oak trees have died from oak wilt (yellow dots). One tree is currently wilting and dropping its leaves (purple dot).

In August, I reported that we’d found oak wilt in Cloverland Township in Vilas County, in Arbor Vitae Township northeast of Woodruff, (on the southern border of Boulder Junction Township), and along Nabish Lake Road in Boulder Junction and Plum Lake Townships.

So, what’s new since then? Another tree killed by oak wilt was identified on the western side of Plum Lake in Plum Lake Township in Vilas County; another tree died in Washington Township just north of the city of Eagle River. I’m still waiting on results from a suspicious tree in northern Three Lakes Township in Oneida County. In many cases spring storms, which occurred during the high-risk period for overland transmission of oak wilt, were to blame for new oak wilt infections. But in some cases, disease was due to logging or pruning that occurred during the high-risk period for overland transmission of oak wilt. It’s important to know where oak wilt is and to minimize your risk.

For more information, visit the DNR oak wilt web page.

 

Continue reading “Oak wilt continues to be found in the north”

Oak wilt update for Rusk, Washburn, and Sawyer counties

Early-summer logging damage resulted in oak wilt infection of nearly 20 mature n. red oaks. Oaks injured during spring are most vulnerable to infection due to an abundance of viable fungal spores, spore-carrying beetles, and large diameter water-conducting vessels in springwood.

Mature northern red oaks killed by oak wilt in Sawyer County. Photo by Paul Cigan

Late-summer aerial and ground surveys revealed new oak wilt infections within northern red oak stands in Rusk, Sawyer and Washburn counties. Below is an update on the finds in each of the counties.

In Rusk County, aerial detection surveys led to the confirmation of 10 new infections on county forest property. Suspected factors for these infections include spring storm damage and latent detection of past infections caused by logging damage during unrestricted spring harvesting. The county forestry department continues to use cut-stump herbicide treatments to control below-ground transmission. They plan to continue follow-up monitoring of treated pockets and have reported encouraging results to date; only a few pockets treated between 2015 and 2016 contained newly infected oaks on or near the edge of the treatment zone.

Continue reading “Oak wilt update for Rusk, Washburn, and Sawyer counties”

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

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

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

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

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.

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