Disease

New UW-Madison Plant Disease Diagnostics Clinic listserv

Posted on by patricialindquist

The UW-Madison Plant Disease Diagnostics Clinic (PDDC) provides expertise in diagnosing plant diseases, and information on plant diseases and their control to agricultural and horticultural producers and businesses, as well as home gardeners, throughout the state of Wisconsin. 

If you are interested in receiving regular updates on the educational materials and programs provided by the PDDC, please email Brian Hudelson at pddc@wisc.edu to have your email address added to the new clinic listserv, “UWPDDCLearn”.  This listserv will provide announcements of when new content is posted to the PDDC website (https://pddc.wisc.edu/), including (but not limited to) new and revised University of Wisconsin Garden Facts/Farm Facts/Pest Alerts fact sheets, the Wisconsin Disease Almanac (a weekly summary of diagnoses made at the PDDC) and monthly clinic web articles.  The listserv will also provide announcements about upcoming PDDC outreach programs. 

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Educational HRD video now available

Posted on by margueriterapp

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

The Wisconsin DNR recently created a short video on Heterobasidion root disease (HRD) to compliment the updated guidelines that were released in 2019. The 5-minute educational video covers HRD biology, its significance as a tree disease, signs and symptoms, as well as preventative measures that landowners can take to reduce its introduction and spread. This is a great video for forestry professionals, landowners and the general public to learn more about HRD. Continue reading “Educational HRD video now available” →

White pine blister rust can girdle branches

Posted on by margueriterapp

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

White pine branches that suddenly turn red may be a sign of white pine blister rust. White pine blister rust is a fungal infection that creates expanding “dead spots” or cankers on the branches or main stem of host trees. Eventually the fungus grows enough to girdle the branch or main stem and the needles fade from green to pale green to rusty red. Orange, spore-producing pustules erupt around the edges of the canker in the spring.

Orange pustules erupt through the bark and around the margins of a white pine blister rust canker. Photo by Jean Romback-Bartels.

Orange pustules erupt through the bark and around the margins of a white pine blister rust canker. Photo by Jean Romback-Bartels.

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Gall rusts on jack pine

Posted on by margueriterapp

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

There are three things you may find interesting about gall rusts on jack pine at this time of year. The first is that as winter recedes, closer examination of the galls on jack pine shows that squirrels like to chew on them. The squirrels seem to prefer the smaller galls, with most chewing marks being observed on galls less than 2” in diameter. They eat the galls by scraping off the outer layers, leaving behind telltale teeth marks.

Chewing marks on a branch gall caused by gall rust.

Squirrels sometimes feed on galls, scraping away the outer layers and leaving teeth marks behind.

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Damage from heavy winter snow and ice

Posted on by margueriterapp

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

Heavy ice and snow loads can cause significant problems for trees. Branches can break under heavy loads, and entire tree tops loaded with snow can come crashing down in windy conditions. Trees that are repeatedly weighed down or tipped over by snow, only to have more snow pile up on them, can be further impacted.

Four images of winter damage to jack pine, including stem failure from gall damage, root failure due to Armillaria root disease.

Clockwise from top left: jack pine broken at site of gall on main stem; trees that break at their base due to heavy snow loads are not able to recover; previous attack from pine root collar weevil (yellow arrow) weakened this tree near its base; heavy snow load and a major root weakened by Armillaria caused this tree to break (yellow arrow) and tip over.

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Protect oak trees by pruning after July, not before

Posted on by margueriterapp

By Don Kissinger, urban forester, 715-348-5746, Don.Kissinger@wisconsin.gov or Paul Cigan, plant pest and disease specialist, 715-416-4920, Paul.Cigan@wisconsin.gov

Anyone with oak trees in their yards or on forested lands should avoid pruning or cutting them from April through July to protect them from oak wilt.

Sap-feeding beetle on diseased oak tree in Sawyer County.

Sap-feeding beetle on diseased oak tree in Sawyer County.

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Severe spruce needle diseases expected in 2020

Posted on by margueriterapp

By Bill McNee, DNR forest health specialist, Oshkosh, bill.mcnee@wisconsin.gov, 920-360-0942

Wet weather in 2019 created ideal conditions for Rhizosphaera kalkhoffii and other needle cast fungi to infect spruce needles. Since it takes about a year for the needles to show symptoms, heavy and widespread needle diseases are expected to be seen on spruce trees in 2020. 

Lower branches of an infected spruce tree have lots of missing needles and some that are browning.

Loss of older needles on an infected spruce.

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Wisconsin DNR Forest Health 2019 Annual Report

Posted on 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 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” →

Oak wilt found in Forest Co. and northern townships

Posted on by margueriterapp

By forest health specialists Paul Cigan, Hayward, paul.cigan@wisconsin.gov, 715-416-4920 and Linda Williams, Woodruff, linda.williams@wisconsin.gov, 920-360-0665

Oak wilt has been found for the first time in Forest County and several new northern townships in 2019. These previously undocumented infections were detected using a combination of ground surveys, forester and landowner reports and aerial survey flights. This deadly fungal disease of red oaks has now been confirmed in 65 of Wisconsin’s 72 counties.

Updated oak wilt detection map shows new county and township detections described in text.

Oak wilt detection map as of January 1, 2020.

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