Scientists predict that tar spot could soon reach as far west as parts of North Dakota and east to New York, further devastating yields. For further reading, please see: Grazing Corn Stalks with Beef Cattle and Corn stover: What is its worth? Each one of those black tar spots is the reproductive structure of the tar spot fungus, which can produce thousands of spores. Scientists predict that tar spot could soon reach as far west as parts of North Dakota and east to … It can currently be found in states such as Iowa, Illinois and Indiana. Tar spot, caused by the fungal pathogen Phyllachora maydis, is a relatively new foliar disease of corn in the United States, first appearing in Illinois and Indiana in 2015.; Look for tar spot to develop during cool temperatures (60-70 ºF, 16-20 ºC), high relative humidity (>75%), frequent cloudy days, and 7+ hours of dew at night. Get notified when we have news, courses, or events of interest to you. Cases of tar spot in corn have been reported over recent weeks in 12 Iowa counties. TAR SPOT LOVES THE MIDWEST SO FAR Figure 1, show the location of these detections. Identified by the distinctive development of stroma, this pathogen in itself is of little economic importance in the production of corn. There is a lot of discussion and questions surrounding tar spot this year in Ontario. Tar Spot, a new disease of corn caused by the fungus Phyllachora maydis, was reported for the first time in Ohio at the end of the 2018 growing season. Tar spot in Illinois corn-2020 It’s early in the season, but before we know it, corn will be chest high and we will be thinking about if in season management is needed. No matter what, it never seems fast enough. The greenness score was meant to understand the level of senescence relative to the tar spot severity level. July 1, 2020. It first appeared in the U.S. in 2015 in Illinois and Indiana. The symptoms of tar spot are primarily the presence of glossy black, raised lesions on leaves, which may be surrounded by dead tissue as the disease progresses (Figure 1). Martin Chilvers, Michigan State University, Department of Plant, Soil and Microbial Sciences, and Kristin Poley, Michigan Corn Marketing Program - Corn tar spot can look somewhat similar to common rust on corn, but the spots do not rub off or break open like rust pustules. During the first few years in the U.S., tar spot appeared to be a minor cosmetic disease with minimal impact to corn yield. Tar spot is a foliar disease of corn caused by the fungus Phyllachora maydis that has recently emerged as an economic concern for corn production in the Midwest. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. MSU is an affirmative-action, equal-opportunity employer. Don’t confuse insect frass with tar spot. Last year (2018) saw a widespread epidemic of corn tar spot across the western side of Michigan, with losses of 50 bushels per acre in particular fields. If you noticed what looks like spots of tar on your corn leaves last year, you weren’t alone. Recommended citation format: Kleczewski, N. "Managing Corn Tar Spot in 2020." In severe cases, tar spot may cause yield loss due to low test weight, reduced kernel fill, poor silage quality and other issues. Tar spot complex in corn is caused by the fungus Phyllachora maydis and Monographella maydis and has been historically found at high elevations in cool, humid areas in Latin America. Known as tar spot, the fungus has continued to infiltrate the Midwest since it was first identified in the U.S. in 2015. See All Pest, Disease and Weed Identification, See All Beer, Hard Cider, and Distilled Spirits, See All Community Planning and Engagement. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. Surrounding some of the black spots may also be a tan halo, which is called a fish-eye lesion. Recently (2017), a new corn disease was identified in Michigan named Tar Spot, caused by Phyllachora maydis. The fungus (Phyllachora maydis) responsible for this disease can overwinter on corn residue and release spores to initiate new infections. Like other corn diseases, the pathogen causing tar spot overwinters in infested corn residue. Why do we need this? These spots are ascomatum (fungal fruiting structures). If tar spot is suspected, a tissue sample should be sent to a laboratory for analysis to confirm the presence of tar spot. Yield loss due to tar spot has not been confirmed in Minnesota. The disease was detected very late in the growing season and no yield loss was reported in fields where the disease was first confirmed. Tar spot is a foliar disease of corn caused by the fungus Phyllachora maydis that has recently emerged as an economic concern for corn production in the Midwest. In 2016, it was found in eastern Iowa, Illinois, Michigan, Wisconsin and Florida. In 2020, tar spot was confirmed in Ontario, Canada and Pennsylvania. Tar spot is the latest new disease of corn to be observed in the U.S. Last year I mentioned that you should “ avoid the cosmic freakout ” around tar spot. Tar spot of corn is a relatively new disease to the U.S. Known as tar spot, the fungus has continued to infiltrate the Midwest since it was first identified in the U.S. in 2015. Tar spot in corn is recognized as small, raised, black-irregular-shaped spots scattered across the leaf surface. This information is for educational purposes only. Although tar spot pressure was relatively light across Michigan in 2019, the disease did continue to spread and is now present across most of our corn acres. Leaves with tar spot have small, raised black and circular spots, which are fungal structures called stromata (Figure 2). In Iowa in 2018, the disease was observed again along … Tar spot, a fungal leaf disease of corn, was recently identified for the first time in Pennsylvania. The project is funded by a $150,000 Rapid Outcomes for Agricultural Research (ROAR) grant from the Foundation for Food and Agricultural Research, which was matched by the National Corn Growers Association, Corteva Agriscience, Wyffels Hybrids, Illinois Corn … Tar spot, caused by the fungal pathogen Phyllachora maydis, is a relatively new foliar disease of corn in the United States, first appearing in Illinois and Indiana in 2015.; Look for tar spot to develop during cool temperatures (60-70 ºF, 16-20 ºC), high relative humidity (>75%), frequent cloudy days, and 7+ hours of dew at night. Tar Spot can cause severe yield loss. In the Latin American region, P. maydis and another fungus coinfect corn plants and cause the tar spot complex. Tar spot appears as small, raised, black spots scattered across the upper and lower leaf surfaces. It appears that scouting is critical to get fungicide applications at the beginning of an epidemic. Check out the MSU Fruit and Vegetable Crop Management Certificate Program! More details about this disease and its causal agent can be found in this publication from Crop Protection Network. Pictures can be emailed to chilvers@msu.edu or via Twitter @MartinChilvers1. There is no threat from this disease to the 2020 crop since corn across the state is already in late reproductive stages and harvest is underway. The pathogen started appearing in Midwest states over the last few years. Michigan State University Plant & Pest Diagnostics, Facebook Checkoff Check-in video interview on tar spot, Fungicide efficacy table for control of corn diseases, YouTube video demonstrating tar spot symptoms. The Agronomy Highlight discussion is an opportunity to ask the author questions about the highlighted article, get updates from Penn State Extension Agronomy Educators around the commonwealth, share observations from your part of the state, and request content for the next issue of Field Crop News. There are no hybrids currently available that are completely resistant to tar spot, but some varieties may have more resistance than others. Iowa State University plant pathologists are part of a new $300,000 research project to study and mitigate tar spot on corn. (Photo by … Fungicides. It was first reported in northwest IN and north-central IL in 2015 by Kiersten Wise, Gail Ruhl and Tom Creswell from Purdue University. By Tom Block 11/30/2020. However, identifying areas where tar spot may have been present in 2020 will be important for monitoring and managing this disease moving forward. Tar Spot, a new disease of corn caused by the fungus Phyllachora maydis, was reported for the first time in Ohio at the end of the 2018 growing season. This is a potentially yield-limiting disease that arrived initially in the US in 2015 and made headlines during the 2018 growing season when there was widespread economic impact in the Midwestern states. This year there have been several additions in products, and some new diseases as well. Tar spot is caused by the fungus Phyllachora maydis and can be identified by the raised, black spots that appear on corn leaves and husks. Tar spot appears as small, raised, black spots scattered across the upper and lower leaf surfaces. Tar Spot of Corn Tar Spot, a new disease of corn caused by the fungus Phyllachora maydis, was reported for the first time in Ohio at the end of the 2018 growing season. Learn more about the weekly Agronomy Highlight discussion . Topics: Crops. Tar spot was first detected in the US in 2015 and has quickly spread through the Corn Belt. These signs are easiest to see on green tissue but can also be found on dried leaves and fodder (Figure 2). The 4-H Name and Emblem have special protections from Congress, protected by code 18 USC 707. When conditions such as high relative humidity and prolonged leaf wetness are present the likelihood of tar spot is greater. Originally observed only in high valleys in Mexico, it has proliferated and spread to South American tropics and parts of North America. In 2020, tar spot was confirmed in Ontario, Canada and Pennsylvania. Kiersten Wise, University of Kentucky . Tar spot, a new disease of corn caused by the fungus Phyllachora maydis, was reported for the first time in Ohio at the end of the 2018 growing season. Permalink . As wet, moderate weather persists this spring, farmers should be on the lookout for this relatively new disease. BP-90-W Diseases of Corn: Tar Spot Identification While a preliminary identification of tar spot can be made visually, a laboratory diagnosis is required to distinguish it correctly from other pathogens. Surrounding some of the black spots may also be a tan halo, which is called a fish-eye lesion. Testing of several fungicides is underway across the state and the Midwest for managing tar spot. Tar spot was first detected in the US in 2015 and has quickly spread through the Corn Belt. This is a potentially yield-limiting disease that arrived initially in the US in 2015 and made headlines during the 2018 growing season when there was widespread economic impact in the Midwestern states. You can also access these additional resources: This article was published by Michigan State University Extension. Raised black lesions indicative of tar spot (Alyssa Collins, Penn State), Figure 2. Tar spot, a fungal leaf disease of corn, was discovered last week for the first time in Pennsylvania in Lancaster County. Tar spot was first detected in the US in 2015 and has quickly spread through the Corn Belt. It is not yet known if tar spot will be a persistent threat to the region. Scientists predict that tar spot could soon reach as far west as parts of North Dakota and east to New York, further devastating yields. Phyllachora maydis is a plant pathogen causing ascomycete diseases in corn, and is more commonly referred to as tar spot. It first appeared in the U.S. in 2015 in Illinois and Indiana. Tar spot in corn. View our privacy policy. Since 2015, this disease has spread and can now be found in several states (Figure 1). Jeffrey W. Dwyer, Director, MSU Extension, East Lansing, MI 48824. Tar spot of corn is a relatively new disease to the U.S. Corn tar spot is caused by the fungus Phyllachora maydis. At that time, it was found mostly in counties close to the Indiana border, as the disease continued to spread from the middle of country where it was first confirmed in 2015. In both situations these were fields with a history of the disease. Corn tar spot is caused by the fungus Phyllachora maydis.