Diseases, Pathogens, & Pests


The 411 on Spotted Lanternfly (November 2021)

Spotted lanternfly has been in the news lately for its threat to agricultural commodities. In terms of the spotted lanternfly’s threat to turf and ornamental plantings, experts say it’s more of a nuisance. So far, spotted lanternfly has been found in the Mid-Atlantic region and some Midwestern states. When lanternflies feed, the adults secrete a sticky substance called honeydew.  Read More

Spotted Lanternfly Found in Indiana (July 2021)

Spotted lanternfly (Lycorma delicatula) was found in Indiana for the first time in Switzerland County earlier this week, the farthest west the insect has been found. This federally regulated invasive species has a detrimental impact upon plant growth and fruit production, especially in vineyards and orchards. Read More

Illinois Forest Health Highlights - 2020

2020 was a challenging year for everyone, but fortunately our team was able to continue visiting state parks and natural areas for forest health monitoring (with extra precautions). Overall, the 2020 growing season was less active for forest health issues than previous years, although a number of pests and diseases continued to be seen. Continuing statewide issues included possible herbicide injury to oak and other hardwood tree species, decline of spruces and pines, rapid mortality of white oaks, and the usual foliar leaf diseases...Read More

APHIS Changes Approach to Fight the Emerald Ash Borer

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) is changing its approach to fight the emerald ash borer (EAB) infestation that has spread through much of the United States. Announced via press release, the agency is publishing a final rule that removes the federal domestic EAB quarantine regulations that have proved ineffective and will redirect resources to more promising methods. Read More

Spotted Lanternfly Discovered in Oregon

According to the state’s department of agriculture, the spotted lanternfly has been discovered in the in Oregon. The Oregon Department of Agriculture released the following pest alert: A spotted lanternfly (SLF), Lycorma delicatula, was found in Oregon for the first time in October 2020 in a shipment of planters and ceramic pots from Pennsylvania. The female specimen was dead and dry. SLF was first found in North America...Read More

Bur Oak Blight Alert (September 2020)

Bur Oak Blight, as the name suggests, is a foliar disease of Bur Oak (Quercus macrocarpa). The disease was first observed in the mid-1990’s in Iowa, Minnesota, Wisconsin, and Nebraska and was discovered in Illinois in 2012. Initial reports were in northern Illinois, but the disease has since spread southward. B.O.B. affects only Bur Oak, particularly the small-acorned...Read More

Be on the Watch for Sudden Oak Death (September 2020)

In 2019, the plant disease, sudden oak death (SOD) has found its way to the Midwest via infected nursery stock and was subsequently distributed to retail stores throughout the Midwest.  Phytophthora ramorum, the causal agent (fungus) of Sudden Oak Death (SOD) was confirmed on ornamental landscape plants.  SOD has been responsible for the death of numerous oaks and other native plants in Oregon and Washington. Read More

Spotted Lanternfly Update (September 2020)

The spotted lanternfly (SLF) (Lycorma delicatula) has recently been detected in Pennsylvania, New York, Virginia, New Jersey, Delaware, and Maryland. Native to East Asia and India, SLF is considered highly invasive due to its wide host range of more than 70 plant species and lack of natural enemies. The insect arrived in North America in egg cases laid on a shipment of decorative stone in 2014 in Pennsylvania.  Read More

Guignardia Leaf Blotch on Horsechestnut and Buckeye (September 2020)

If you have noticed lately, the leaves of buckeyes and horse chestnuts (Aesculus spp.) look pretty brown and scorched.  This is probably due to a fungal leaf disease known as Guignardia leaf blotch (GLB).  Most Aesculus spp. are susceptible (i.e. Ohio, red, and yellow) however, bottlebrush buckeye (A. parviflora) and some varieties of Ohio buckeye...Read More

Keep an Eye Out for Asian Long-Horned Beetle (September 2020)

While the Asian longhorned beetle (ALB) was eradicated from the Chicago land area back in the early 2000’s it is still important to be vigilant. For the past decade, we have been focused on the emerald ash borer (EAB), but the threat from ALB is still very real and is borne out with the recent discovery in South Carolina and a nearby infestation in Ohio. The ALB is an exotic (not native to North America) invasive...Read More

Biscogniauxia or Hypoxylon Canker on Oaks and Other Hardwood Species (September 2020)

I have received a number of reports this summer of white “pads” (fungal mats), and oozing sap on the bark and trunks of oaks and other hardwood species.  It is probably Hypoxylon or another related canker-causing fungus.  Cankers are generally defined as wounds that never really heal.  Most canker-causing fungi are opportunistic and are considered secondary agents, meaning they typically attack stressed urban, landscape...Read More 

Asian Longhorned Beetle Eradicated from Canada (September 2020)

According to an announcement via, the Asian longhorned beetle (ALHB) has been eradicated from Canada. Read a summary of the report below or continue to the website for the full report: The Asian longhorned beetle (ALHB) has been eradicated from the cities of Mississauga and Toronto in the province of Ontario. This was the only known population of ALHB in Canada. ALHB is a highly destructive...Read More

Pine Beetle Update (September 2020) - CLICK HERE

Oak Wilt (July 2020)

Oak wilt is a serious fungal disease which continues to kill oak trees in residential areas, parks, farm woodlots, and forests throughout Illinois. The oak wilt pathogen was first detected in Wisconsin in 1944 and has slowly spread throughout the central and eastern United States, including Illinois. Oak trees are the only known host. Oaks trees within the red and black group (pointed leaf lobes) are more susceptible than oaks...Read More

Black Canker of Willow (July 2020)

Willows (Salix spp.) can be beautiful additions to the landscape. These iconic trees can be found growing naturally in river bottoms, along ponds, rivers, and streams; all areas with consistently moist soil. In the landscape, where soil moisture is much more variable, willows can be stressed by drought, increasing damage from a number of canker diseases to which they are already very susceptible, including Botryosphaeria...Learn More

APHIS Declares Elimination of Ralstonia Incidents (June 2020)

On June 11, the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) and its State partners announced they have successfully completed actions to eliminate Ralstonia solanacearum race 3 biovar 2 from U.S. greenhouses. This announcement comes just two months after the pathogen was first detected in a Michigan greenhouse in April. R. solanacearum race 3 biovar 2...Read More

Needlecast Diseases: Not Just a Spruce Problem (June 2020)

Many are familiar with Rhizosphaera needlecast of spruce. If you aren’t, please see these two articles by Janna Beckerman and  Megan Haas for more information about the disease and it’s management on spruce. The common name for the disease, needlecast, describes the ultimate fate of the needles: they are cast off. Loss of leaves or needles hurts some trees more than others...Read More

Keeping Tabs on the Spotted Lanternfly (June 2020)

For those living in Pennsylvania and the Mid-Atlantic region, the spotted lanternfly (Lycorma delicatula) must carefully be tracked and monitored. The spotted lanternfly is an invasive species from China that first arrived in Berks County, Pennsylvania, in September 2014. Ever since its arrival, the spotted lanternfly population has steadily increased. The spotted lanternfly is a planthopper and prefers to feed on the tree of heaven...Read More

What You Need to Know About the Current Ralstonia Situation (May 2020)

Since the discovery of Ralstonia solanacearum Race 3 biovar 2 in a Michigan greenhouse last month, experts from across the industry have moved quickly to make sure the problem does not spread. Last week, AmericanHort’s Horticultural Research Institute hosted a webinar that offered vital information on the challenges in identifying this strain of Ralstonia, and what you can do to minimize risk...Read More

Whoa! Don’t Get Walloped by Whiteflies (April 2020)

For U.S. produce growers, whiteflies are pernicious pests that feed on produce, ornamental plants and hemp throughout North America. There are more than 1,500 species of the eponymous pale-winged bug.  According to J.C. Chong, turf and ornamentals entomologist at Clemson University, the greenhouse whitefly (Trialeurodes vaporariorum) and especially the sweetpotato whitefly B-biotype (Bemisia tabaci...Read More

The Battle Against Rose Rosette (February 2020)

One of the most important tenets of plant pathology is that the first step to effectively controlling a plant disease is identifying its cause. Otherwise, control measures could be ineffective, leading to further plant loss and wasted time and resources. This is especially true of rose rosette disease (RRD). Typical symptoms of RRD are known and widely accepted; they include rapid elongation of new shoots...Read More

Scouting for Boxwood Blight (February 2020)

The 2019 growing season was a big year for boxwood blight in Oregon. The disease, caused by the pathogen Calonectria (Cylindrocladium) pseudonaviculata, has caused substantial damage to boxwood shrubs in U.S. nurseries and gardens since it was first discovered in 2011. Only two Oregon nurseries found boxwood blight in 2011. That number expanded to 12 by 2019. So, how do you know...Read More

Fight the Fire Blight (September 2019)

It’s common knowledge that certain bacteria can make people sick, but did you know that bacteria can cause plant diseases as well? They most certainly do. The first bacterial pathogen to be identified was anthrax, a disease affecting sheep and cattle in 1876. Shortly after that, the first bacterial plant disease was confirmed – fire blight on apples and pears. Read More

Pesticide Use & Regulation in Illinois

We are governed by the Illinois Pesticide Act (415 ILCS 60) which recognizes that "pesticides are valuable and necessary to Illinois' agricultural production and to the protection of man and his environment from pests, but it is essential to our general health and welfare that they be regulated to prevent adverse effects on man and his environment." 

Individuals wishing to purchase and/or apply restricted use pesticides in Illinois are required to successfully complete a competency examination and receive a license from the Illinois Department of Agriculture. LEARN MORE

Turf Management Tool - Product Efficacy Against Specific Pests

Search for a particular herbicide, fungicide, or insecticide by typing the product name into the search bar at the top of the page to learn more about that product.  Or to learn more information about product ratings against particular pests you can click on the diseases, insects, or weeds button on the home page, click on a particular pest, and find the products rated as most effective against that particular pest on a 1 to 4 scale (4 being the best).  

Click here to access the tool

Bayer Introduces New Spanish Pest Identification Guide for Greenhouses and Nurseries (July 2020)

The Environmental Science business of Bayer, part of the company’s Crop Science division, has created a new Spanish Pest Identification Guide to effectively communicate important technical information about pests to Spanish-speaking laborers in greenhouse and nursery operations. Digital versions of the guide — in both Spanish and English — can be viewed, printed or downloaded for free...Read More

Boxwood Blight

Emerald Ash Borer

Updated Guide to Chemical Control of Emerald Ash Borer - CLICK HERE

What is Emerald Ash Borer - CLICK HERE
Emerald Ash Borer Detection by County and Year -

Insecticide Options for Protecting Ash Trees from Emerald Ash Borer - CLICK HERE
New Tips for Managing Emerald Ash Borer (Jan 2019) - CLICK HERE

Box Tree Moth

Box tree moth (Cydalima perspectalis) is considered a high-consequence defoliating pest of boxwood, with other possible hosts. Box tree moth (BTM) is a Eurasian native moth. The larvae are voracious defoliators of Buxus. The pest is established in western Europe, where it has been extremely damaging to boxwood in the landscape. Roughly two years ago, it was found in an urban Toronto neighborhood. In May 2021, the Canadian Food Inspection Agency (CFIA) confirmed the presence of box tree moth (Cydalima perspectalis) in a St. Catharines, Ontario, Canada nursery. On May 26, 2021, USDA imposed a federal order prohibiting the importation of all Buxus, Ilex, and Euonymus spp.plants from anywhere in Canada until further notice. 

Box Tree Moth Resources
Horticultural Research Institute Webinar on Box Tree Moth - CLICK HERE
Insecticide Options for Box Tree Moth Management - CLICK HERE
Photographic Guide of Boxwood Pests & Diseases - CLICK HERE
ox Tree Moth Management Practices for Growers -

Japanese Beetle

Following a series of regulatory incidents in 2017, the state of Colorado is apparently moving to tighten requirements for some incoming shipments of container-grown plants.  In rule changes that will take effect April 15, 2018 if approved as expected, container-grown plants in pots up to 16 inches in diameter will continue to be able to be certified and shipped under the Japanese Beetle Harmonization Plan’s Container Accreditation option.  However, nurseries not producing consistent with that option will need to use an approved insecticide dip or drench treatment for any containers larger than 7 inches in diameter or of a volume classified in the American Standard for Nursery Stock as a trade #1 or larger. The requirement will apply to incoming plants from Japanese beetle-infested areas, and also to Colorado-grown plants moving out of areas declared infested in the state. 

Spotted Lanternfly

 This plant hopper feeds on a wide range of plants and trees. It is a serious threat to grape, apple, oak, walnut, poplar, stone fruit and logging industries. Grapes, orchard fruits, hops, and trees are most at risk. It is native to China and was first detected in Pennsylvania in September 2014. Spotted lanternfly feeds on a wide range of fruit, ornamental and woody trees, with tree-of-heaven being one of the preferred hosts.


Brian Walsh, Penn State Extension Horticulture Educator based in Berks County, Pennsylvania, discusses the latest SLF management research on insecticide trials and treatment recommendations during a Horticultural Research Institute THRIVE Webinar - WATCH NOW

Management of Invasive Plants and Pests of Illinois

Illinois Designated Exotic Weeds List (525 ILCS 10/) Illinois Exotic Weed Act - It shall be unlawful for any person, corporation, political subdivision, agency or department of the State to buy, sell, offer for sale, distribute or plant seeds, plants or plant parts of exotic weeds without a permit issued by the Department of Natural Resources. CLICK HERE TO ACCESS LIST

Illinois Designated Noxious Weeds List - CLICK HERE

University of Illinois Extension Guide to Identifying Exotic Weeds - CLICK HERE

How to Identify Common Invasive Plants (Videos from The Morton Arboretum)