First reported in the U.S. in Illinois in 1924, it has been a problem in Mid-Atlantic States and the eastern region of the Corn Belt for decades. Table 1. Entomology Image Gallery > Plant Diseases and Damage > Corn > Gray Leaf Spot. Denazareno, N.R.X., P.E. Several batches of spores from lesions can be produced during the growing season, resulting in severe epidemics [1, 2]. Individual lesions may be 3 to 4 inches long and 1/16 to 1/8 inch wide, depending on the distance between veins. The fungus Cercospora zeaemaydis causes this common leaf blight. This article will discuss how to diagnose Gray leaf spot, the disease cycle of the pathogen, impacts of the disease, and management recommendations. After about two weeks, lesions appear tan to brown in color and rectangular in shape, bordered by the veins of the leaf (Fig. Corn also requires ample space as it grows large in size and is pollinated by wind. It is essential that resistant varieties be used in fields with a history of Gray leaf spot, particularly in Delaware where the disease is endemic. As many as 5-20 gray leaf spot lesions are present on the ear leaf and, in some fields GLS lesions are also present on the leaf above the ear leaf. As the lesions expand, large areas of leaf tissue can be destroyed (Figure 2). Gray Leaf Spot in Corn Gray leaf spot (G LS) is caused by the fungus Cercospora zeae-maydis. Gray Leaf Spot is a fungus found in corn nearly every growing season. Gray leaf spot on corn, caused by the fungus Cercospora zeae-maydis, is a peren- nial and economically damaging disease in the United States. It attacks leaves, leaf sheaths, stalks, and sometimes outer Gray leaf spot is typically the most serious foliar disease of corn in the U.S. corn belt, although other diseases can be more important in areas and years where weather conditions do not favor gray leaf spot. Cause. Gray Leaf Spot. Gray leaf spot requires extended periods of high humidity and warm conditions. With time lesions can coalesce and form large necrotic areas and decimate the canopy (Figure 2). Scouts should pay particular attention to the lower three leaves of the corn plant from the period just before tasseling to two weeks after tasseling. In grasses other than maize it is caused by Pyricularia grisea, which only infects perennial ryegrass, tall fescue, and St. Augustine grass in places with warm and rainy climates. When temperatures begin to increase during the spring, the fungus will produce spores. Early lesions are small, necrotic spots with yellow halos that gradually expand to full-sized lesions. Under the proper circumstances significant loss photosynthetic area of the canopy occurs, resulting in reduced yield. 67:842. Gray leaf spot is due to a fungus called Cercospora zeae-maydis, and can be economically damaging to corn crops. It is believed that an increase in no-till and conservation tillage farming has contributed to the increase of this disease [1]. Gray leaf spot severity is unpredictable and multiple factors should be considered when making the decision to use fungicides to control Gray leaf spot. Corn is the only crop know to be attacked by this fungus. Gray leaf spot normally thrives on susceptible hybrids when temperature and humidity are high. Practices that promote the decomposition of corn residue will greatly reduce the amount of the fungus present to cause disease [6]. Airborne spores are spread locally and regionally from corn debris. When the temperature is in the high 90s and grass is too wet to mow at 11:30 a.m., scout gray leaf spot. There are numerous fungicides available for control of Gray leaf spot. Several years out of corn may be required in no-till situations. Lesions of GLS elongating on corn leaf. Spores are dispersed by wind and splashing water. Gray Leaf Spot: Corn Farmers' Biggest Rival As every veteran corn producer knows, corn is susceptible to a myriad of foliar fungal diseases . Gray Leaf Spot, or GLS, is only known to affect corn. During the growing season, foliar fungicides can be used to manage gray leaf spot outbreaks. First reported in the U.S. in Illinois in 1924, it has been a problem in Mid-Atlantic States and the eastern region of the Corn Belt for decades. The spores can be wind-blown or water-splashed onto the lower leaves. Jennifer M. Rees, Extension Educator Tamra A. Jackson, Extension Plant Pathologist. Gray leaf spot of corn, while of little consequence in the US before 1970, has become a major concern to many corn producers in recent years. Frances M. Latterell, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. Symptomatic leaves have... Disease Cycle. This article is in the public domain and not copyrightable. The light-brown color changes to a silver-grey color as environmental conditions (warm and humid) allow for the production of fungal conidia (spore-forming structures). GRAY LEAF SPOT OF CORN Patrick E. Lipps Professor/State Extension Specialist Department of Plant Pathology The Ohio State University OARDC, Wooster Gray leaf spot (GLS) is a foliar disease of com caused by the residue-borne fungus, Cercospora zeae-maydis. (Source: Dr. Pat Lipps (ret.) Symptoms and Signs. Severe outbreaks of Gray leaf spot can result in losses resulting from  reduced photosynthesis and grain fill [2]. much impact gray leaf spot will have on corn production. Wise says some level of gray leaf spot can be found in almost corn field in Indiana, but she cautions that deciding to apply fungicide should be based on the level of disease and the four factors she outlined. Gray Leaf Spot of Corn Gray leaf spot of corn is caused by the fungus Cercospora zeae-maydis. One of the most common foliar corn diseases in Tennessee is gray leaf spot (caused by a fungus – Cercospora zea-maydis), especially in continuous corn fields (see Images 1 and 2). Gray leaf spot of corn is caused by a fungal pathogen Cercospora zeae-maydis (Syn. Most fungicides provide protection for an average of 21-28 days. Customers can see the effectiveness of hybrid resistance based off of a score (ranging from 1 to 9) that is assigned to Pioneer brand products. GLS is considered one of the most significant yield-limiting diseases of corn worldwide. This can result in a higher risk of stalk lodging and stalk rots due to a loss of structural integrity. Signs of Gray leaf spot are often first noticed on the lower leaves. Gray leaf spot lesions on corn leaves hinder photosynthetic activity, reducing carbohydrates allocated towards grain fill. Gray leaf spot starts as small necrotic (dead tissue) light-tan spots. It occurs almost every growing season and is considered to be the most serious disease of corn in the Corn Belt, year in and year out. Entomology Image Gallery > Plant Diseases and Damage > Corn > Gray Leaf Spot. In accordance with Federal law and U.S. Department of Agriculture policy, Cooperative Extension is prohibited from discriminating on the basis of race, color, national origin, sex, age, or disability. College of Agriculture & Natural Resources, 531 South College Avenue Lesions on resistant hybrids are smaller and the disease develops more slowly than on susceptible hybrids [3, 4]. Farmers must consider the cost of the application and market value of their corn before determining if fungicides will be an economical solution to GLS. The fungus survives the winter in undecomposed corn residue. The disease was first reported in Illinois in 1924, and has increased in prevalence throughout corn growing regions since 1988. In years where disease risk is high or growers have planted susceptible hybrids in no till fields, fungicides may be considered. Figure 1. It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. Estimated yield loss based off of percent of tissue infected by gray leaf spot (Lipps, 1998). As many as 5-20 gray leaf spot lesions are present on the ear leaf and, in some fields GLS lesions are also present on the leaf above the ear leaf. There are two fungal pathogens that cause GLS: Cercospora zeae-maydis and Cercospora zeina. As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). Signs of Gray leaf spot are often first noticed on the lower leaves. Gray leaf spot overwinters on corn residue and can be especially problematic in corn planted behind corn. 1), caused by the fungus Cercospora zeae-maydis, has been generally asso-ciated with the corn pro-duction areas west of the Blue Ridge Mountains. This fungus survives the winter on corn residue and as temperatures warm up in the spring, spores produced by the overwintering fungus will infect developing corn plants. Newark, DE 19716 Gray leaf spot (GLS), northern corn leaf blight (NCLB), and tar spot have all been found in various locations over the last week or so. The fungus does not grow well on non-host residues. Symptomatic leaves have small, tan, rectangular lesions surrounded with yellow halos, which are not easily distinguished from lesions caused by other foliar pathogens of corn. Gray leaf spot is one of the most common foliar diseases in Delaware corn and can significantly reduce corn yields under favorable conditions. Begin scouting for gray leaf spot in corn about 2 weeks before expected tassel emergence. Under some conditions lesions may occur on stalks [2]. Photo: N. Kleczewski, 531 South College Avenue It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. C. zeae maydis can survive on corn residue for one to two years. Most fields do not immediately need a fungicide application for disease management purposes. One of the most important requirements for growing corn is a high quality soil which is deep, fertile and well-draining with a pH between 6.0 and 6.8. Introduction. Crop Observation and Recommendation network. Most fungicides provide protection for an average of 21-28 days. Gray leaf spot (GLS) (Figure 1) caused by Cercospora zeae-maydis is considered the world’s most yield-limiting disease on corn. These spores can easily travel through water to young plants, often infecting the plants lower leaves first. And, we’re monitoring low level development of gray leaf spot and northern corn leaf blight. Other diseases observed at various locations included common rust, southern rust, northern corn leaf blight and bacterial leaf streak. Infection by the GLS fungus damages the plant by reducing the amount of healthy leaf area capable of producing the energy needed to grow/maintain the plant and make grain. From its first appear-ance in Kansas in the Republican River Valley in 1989, Conducive weather conditions encourage the rapid spread of disease near the end of summer and early fall, when corn plants allocate more resources to grainfill. Lipps, and L.V. Field history. Regardless of planting date, initial symptoms of gray leaf spot generally will not appear until anthesis. Gray Leaf Spot of Corn: A Disease on the Move. Serious outbreaks of the disease first occurred in the early to mid 1970s in low-lying areas in the mountainous regions of Kentucky, North Carolina, Tennessee and Virginia. As sporulation commences, the lesions take on a more gray coloration. Because early lesions are ambiguous, they are easily confused with other foliar diseases such as anthracnose leaf blight, eyespot, or common rust. Rotating away from corn may help reduce local levels of inoculum and reduce Gray leaf spot severity in the following corn crop. The disease is first detectable as small grayish lesions on the lower leaves, which run parallel to the veins. Gray leaf spot, caused by the fungus Cercospora zeae maydis is the most significant yield-limiting disease of corn worldwide [1]. While doing this, it is important to look back at this past year’s performance and evaluate how each product responded to the environmental conditions such as disease. Figure 1. These leaves contribute at least 75 percent of the carbohydrate content of the ear. Figure 7­7. Northern corn leaf blight can be identified by the distinctive lesions that form on the leav… Lesions of GLS elongating on corn leaf. This NebGuide discusses the . Burying residue as little as 10-cm below the surface can greatly reduce primary infection levels. The most frequent of these diseases, gray leaf spot, has been increasing in economic impact in many regions of the world over the past 10 years. Gray leaf spot of corn is being reported across the state. 67:842. The most frequent of these diseases, gray leaf spot, has been increasing in economic impact in many regions of the world over the past 10 years. This institution is an equal opportunity provider. Gray leaf spot and yield losses in corn. As every veteran corn producer knows, corn is susceptible to a myriad of foliar fungal diseases. The most aggressive of these diseases, gray leaf spot, has been increasing in economic impact in many regions of the world over the past 10 years. Frances M. Latterell, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. In the 1960s and 1970s, the disease became of concern in the eastern United States. Gray leaf spot was first observed in corn in 1925 in Illinois and then more extensively in eastern seaboard states, such as the Carolinas and Virginia, in the 1940’s. Basic requirements Corn is best grown in warm, tropical and sub-tropical regions as it requires warm soils to develop optimally. Gray Leaf Spot. It poses a serious threat to corn production in many areas of the eastern United States, including Virginia, and more recently in large areas of the U. S. Corn Belt and Africa. In minimum tillage fields with a history of GLS, symptoms can occur on the lower leaves prior to tasseling. (302) 831-2501. This pathogen was not seen as an economic threat until the mid 1970’s when no-till and other conservation tillage practices were becoming more prevalent. Entire leaves can be killed when weather conditions are favorable, and rapid disease progression causes lesions to merge. Current data on tar spot indicate it likely doesn’t need to be controlled. In growing seasons when these conditions prevail, the risk for disease development increases. Average yield increase of hybrids, with varying levels of resistance to GLS, due to a foliar fungicide application in a three- year University of Tennessee/Pioneer research study with very high GLS pressure. Foliar diseases, like gray leaf spot, require high humidity, moisture and moderate to warm temperatures for disease development. Albert E. Rossi, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. symptoms, impacts and management of this disease. Wise, K. 2010. This article is in the public domain and not copyrightable. Infection of corn leaves and disease development are favored by warm (80s°F), humid (>90% for 12+ hours) weather.” These expand in length to become rectangular and can reach 2 inches but they are limited within leaf veins (regular). Additionally, it is favored in situations with reduced tillage and continuous corn. Gray leaf spot (GLS) (Fig-ure 1) caused by . Corn plants are very heavy feeders and even the most fertile of soils may need to supplemented with nutrients as the plants develop, particularly nitrogen. Spores from both of these pathogens can either be splashed up onto foliage or deposited by the wind. Plant Dis. Gray leaf spot (GLS) (Figure 1) caused by Cercospora zeae-maydis is considered the world’s most yield-limiting disease on corn. Field corn represents the largest portion of the acreage grown. Patrick Lipps, 1998. Disease Facts Gray leaf spot is caused by the fungus Cercospora zeae-maydis.. Epidemics of gray leaf spot have been observed in New York State in the Southern Tier and the Hudson River Valley. In the late spring, following periods of high humidity, the... Impacts of the Disease. Predicted yield losses resulting from Gray leaf spot. Fungicides were applied at growth stage V12, R1 and R3. Susceptible hybrids are more likely to benefit from a foliar fungicide application, but resistant varieties may benefit as well under high gray leaf spot pressure (. Introduction. Individual results may vary. Crop rotation away from corn can reduce disease pressure, but multiple years may be necessary in no-till scenarios. Grey leaf spot (GLS) is a foliar fungal disease that affects maize, also known as corn. Eight products at various application timings were evaluated (Table 1). 1B). If at least 50% of plants in a field have disease present on the third leaf below the ear leaf or higher prior to tasseling, the hybrid is susceptible, and the conditions are favorable for disease, then a spray may be warranted. Fungicide efficacy for control of gray leaf spot. These lesions are not rectangular but rather amorphous, with tan or gray centers. Coloration of initial lesions can range from tan to brown before sporulation begins. When selecting a fungicide, it is important to keep in mind the efficacy of the available products (. Lesion size and color can vary depending on the corn hybrid. Numerous rectangular lesions caused by gray leaf spot. Gray Leaf Spot: Robbing Corn Yields. (Wise, 2019). Disease development is favored by warm temperatures, 80°F or 27 °C; and high humidity, relative humidity of 90% or higher for 12 hours or more. Gray leaf spot (GLS), caused by the fungus Cercospora zeae-maydis, has been one of the most prevalent foliar fungal diseases of corn in the state of Ohio ever since it was first reported in parts of Pickaway, Ross, Pike and Scioto counties in 1978. Under favorable environmental conditions spores are produced on foliar lesions and spread to upper leaves and other plants. Gray Leaf Spot: Corn Farmers' Biggest Rival As every veteran corn producer knows, corn is susceptible to a myriad of foliar fungal diseases . Figure 2. The extent to which gray leaf spot damages crop yields can be estimated based on the extent to which leaves are infected relative to grainfill (. Photo: N Kleczewski. Foliar fungal diseases of primary concern in Michigan are northern corn leaf blight and gray leaf spot. Since the mid-1990s, the disease has increased in importance in Indiana, and now is the one of the most important foliar diseases of corn in the state. Corn plants susceptible and resistant to gray leaf spot; Gray leaf spot on inbred ear leaf; Gray leaf spot … Gray Leaf Spot and Northern Corn Leaf Blight share some similarities, but it's important to accurately diagnose which disease is affecting your corn crop. Gray leaf spot (GLS) is a foliar fungal disease that affects grasses. Companies use different scales for rating resistance, so be sure to check the scale. 1A). Issue 98-23. Symptoms seen on corn include leaf lesions, discoloration (chlorosis), and foliar blight. Life cycle of gray leaf spot Cercospora zeae-maydis in corn. Gray leaf spot (GLS) is a common fungal disease in the United States caused by the pathogen. From its first appear-ance in Kansas in the Republican River Valley in 1989, it can now be found wherever corn is grown in the state. With the warmer temperatures and high relative humidity during recent weeks, some crop consultants and Extension educators are reporting that northern corn leaf blight seems to be slowing its spread, while gray leaf spot (Figure 2) is becoming increasingly important and moving higher in the plant canopy. Gray leaf spot disease cycle. No surfactant was included in applications made at V12. Gray Leaf Spot. Plant Dis. Cultural practices reduce local levels of inoculum, which may help reduce disease progress and impact on yield. Table 1. The fungus survives in corn residue, and, consequently, the disease is often more severe in corn following corn. When lesions are at the ear leaf or above prior to flowering, the potential for yield loss is present. Gray Leaf Spot Disease of Corn Erik L. Stromberg, Extension Plant Pathologist, Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech In Virginia gray leaf spot disease of corn (Fig. Newark, DE 19716, Recipe: Cantaloupe and watermelon smoothie, Expanded Food and Nutrition Education Program (EFNEP), Silk Stage Sweet Corn - Action Thresholds, Research and Extension Demonstration Results, Brown Marmorated Stink Bug (BMSB) Management, Research, and Resources, Statewide Drug Prevention & Lifeskills Program, Personal Financial Management Initiatives, General Information on what, how, why and where soil is tested, Continuing Education for Nutrient Management. Approximately one in two plants are infected, and corn is at growth stage VT/R1. Corn is the only crop know to be attacked by this fungus. 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