Grey leaf spot (GLS) is a foliar fungal disease that affects maize, also known as corn. Weather. As infection progresses, lesions begin to take on a more distinct shape. 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. 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. Introduction. Coloration of initial lesions can range from tan to brown before sporulation begins. Mature lesions are tan to gray and expand linearly between leaf veins giving a rectangular shape. Gray leaf spot develops first on lower leaves and may spread upward to the highest leaf. Gray leaf spot (GLS) (Fig-ure 1) caused by . (Source: Dr. Pat Lipps (ret.) Identification. 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. Numerous rectangular lesions caused by gray leaf spot. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Foliar diseases, such as gray leaf spot, northern corn leaf blight, and southern rust, were estimated to cause annual losses ranging from 19,029 to 244,149 metric tons from 2012 to 2015 in Kentucky. Frances M. Latterell, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. Damage can be more severe when developing lesions progress past the ear leaf around pollination time. This institution is an equal opportunity provider. 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. 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. The majority of disease spread via spores occurs over a relatively short distance, but spores may escape the canopy and travel great distances. Gray Leaf Spot Now that harvest is completed, it is time to start thinking about next year and making seed corn selection decisions. 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. Gray leaf spot (GLS) (Figure 1) caused by Cercospora zeae-maydis is considered the world’s most yield-limiting disease on corn. This application occurred at approximately 1/2 milkline (R5). This fungus will overwinter on plant residue on the soil’s surface. Most fields do not immediately need a fungicide application for disease management purposes. Approximately one in two plants are infected, and corn is at growth stage VT/R1. After about two weeks, lesions appear tan to brown in color and rectangular in shape, bordered by the veins of the leaf (Fig. Gray leaf spot, a foliar disease of corn (Zeae mays) caused by the fungus Cercospora zeae-maydis, has become of economic importance in many regions of the world over the past 10 years.Gray leaf spot was first described in the U.S.A. in 1925 on corn in Alexander County, IL. Gray leaf spot overwinters in and on corn debris left above and on the soil surface. Disease in the trials was assess… Gray leaf spot is due to a fungus called Cercospora zeae-maydis, and can be economically damaging to corn crops. Click image to enlarge. symptoms, impacts and management of this disease. Begin scouting for gray leaf spot in corn about 2 weeks before expected tassel emergence. In order to cause severe yield reduction the disease must damage leaves around the silking growth stage. GLS is considered one of the most significant yield-limiting diseases of corn worldwide. Rotating away from corn may help reduce local levels of inoculum and reduce Gray leaf spot severity in the following corn crop. Several batches of spores from lesions can be produced during the growing season, resulting in severe epidemics [1, 2]. 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. 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 requires extended periods of high humidity and warm conditions. Thus, there is likely not much to do at this point, but to document which fields have which diseases. The disease is first detectable as small grayish lesions on the lower leaves, which run parallel to the veins. 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. Other diseases observed at various locations included common rust, southern rust, northern corn leaf blight and bacterial leaf streak. Gray leaf spot is caused by the fungus Cercospora zeae-maydis. Figure 7­7. Because gray leaf spot survives in corn residue, the risk of disease increases when corn is planted back into a field that was in corn the previous year. Crop Observation and Recommendation network. From its first appear-ance in Kansas in the Republican River Valley in 1989, This article is in the public domain and not copyrightable. 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. Corn plants susceptible and resistant to gray leaf spot; Gray leaf spot on inbred ear leaf; Gray leaf spot … This article will discuss how to diagnose Gray leaf spot, the disease cycle of the pathogen, impacts of the disease, and management recommendations. 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. 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). C. zeae maydis overwinters on corn residue. For this reason it is important to scout fields for symptoms of Gray leaf spot and apply fungicides only when they are needed. Predicted yield losses resulting from Gray leaf spot. Gray Leaf Spot of Corn. Always follow label directions when applying a fungicide. 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 (. Gray leaf spot disease cycle. Immature GLS lesions can be easily confused with lesions caused by other pathogens; e.g., eyespot Kabatiella), anthracnose (Colletrichum). Infection of corn leaves and disease development are favored by warm (80s°F), humid (>90% for 12+ hours) weather.” Gray leaf spot is now recognized as one of the most significant yield-limiting diseases of corn worldwide. Photo: N Kleczewski. All corn hybrids and inbreds are susceptible to Gray Leaf Spot (GLS). Gray Leaf Spot of Field Corn. Gray leaf spot (GLS) was observed at all locations, although severity was low (Table 1). 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. In growing seasons when these conditions prevail, the risk for disease development increases. This can result in a higher risk of stalk lodging and stalk rots due to a loss of structural integrity. Over time the lesions of Gray leaf spot coalesce to form large necrotic areas. 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. 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. The foregoing is provided for informational use only. … Gray leaf spot lesions on corn leaves hinder photosynthetic activity, reducing carbohydrates allocated towards grain fill. Northern corn leaf blight can be identified by the distinctive lesions that form on the leav… Symptoms seen on corn include leaf lesions, discoloration (chlorosis), and foliar blight. Because a decrease in functioning leaf area limits photosynthates dedicated towards grainfill, the plant might mobilize more carbohydrates from the stalk to fill kernels. Symptomatic leaves have... Disease Cycle. Gray leaf spot and yield losses in corn. Immature GLS lesions can be easily confused with lesions caused by other pathogens; e.g., … And she warns that many fields contain common rust. It is becoming very late in the season to try to control GLS or NCLB. Gray Leaf Spot. 67:842. 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 (. Gray leaf spot (GLS) (Figure 1) caused by Cercospora zeae-maydis is considered the world’s most yield-limiting disease on corn. These leaves contribute at least 75 percent of the carbohydrate content of the ear. ™ ® Trademarks of Corteva Agriscience and its affiliated companies. Lesions often have a yellow halo (b). Gray leaf spot infection on corn. It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. Symptoms 1 Regardless of planting date, initial symptoms of gray leaf spot generally will not appear until anthesis. Cultural practices reduce local levels of inoculum, which may help reduce disease progress and impact on yield. Corn is the only crop know to be attacked by this fungus. Applications made too early may mean their protection has worn off before diseases reach critical levels. C. zeae maydis can survive on corn residue for one to two years. Madden, University of Delaware Newark, DE 19716 USA. When selecting a fungicide, it is important to keep in mind the efficacy of the available products (. Lesions of GLS elongating on corn leaf. Gray leaf spot lesions begin as small necrotic pinpoints with chlorotic halos, these are more visible when leaves are backlit. Hybrids vary greatly in their response to this disease and these values should be viewed as guidelines only. It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. 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. It attacks leaves, leaf sheaths, stalks, and sometimes outer It can be confused with other foliar diseases of corn. 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. Scores for Gray leaf spot resistance are available from seed companies and dealers. Gray Leaf Spot and Northern Corn Leaf Blight. 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. Individual results may vary. 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. Field history. Under the proper circumstances significant loss photosynthetic area of the canopy occurs, resulting in reduced yield. Entire leaves can be killed when weather conditions are favorable, and rapid disease progression causes lesions to merge. The fungus Cercospora zeaemaydis causes this common leaf blight. The fungus will usually survive for no more than two years; often, one year away from corn allows for substantial reduction in risk. Additionally, it is favored in situations with reduced tillage and continuous corn. Lesions on resistant hybrids are smaller and the disease develops more slowly than on susceptible hybrids [3, 4]. 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. Most fungicides provide protection for an average of 21-28 days. Table 1. 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. 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. Entomology Image Gallery > Plant Diseases and Damage > Corn > Gray Leaf Spot. Timing of application varied among products and was suggested by the companies contributing each product. Gray leaf spot is one of the most important foliar diseases of corn and it is caused by Cercospora zeae-maydis. Symptoms and Signs. And, we’re monitoring low level development of gray leaf spot and northern corn leaf blight. Hybrid, environment, and the pathogen all influence symptom expression and other foliar pathogens may cause similar symptoms. 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. Practices that promote the decomposition of corn residue will greatly reduce the amount of the fungus present to cause disease [6]. corn diseases, it is recommended that suspicious samples be sent to the Arkansas Plant Health Clinic in Fayetteville for proper identification. Several years out of corn may be required in no-till situations. Please contact your Pioneer sales professional for information and suggestions specific to your operation. However, there is no guarantee that fungicide applications will result in economic returns, especially if they are applied to highly resistant hybrids in fields with little disease. Gray leaf spot of corn is being reported across the state. Gray Leaf Spot: Corn Farmers' Biggest Rival As every veteran corn producer knows, corn is susceptible to a myriad of foliar fungal diseases . There are two fungal pathogens that cause GLS: Cercospora zeae-maydis and Cercospora zeina. 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, a foliar disease of corn (Zeae mays) caused by the fungus Cercospora zeae-maydis, has become of economic importance in many regions of the world over the past 10 years.Gray leaf spot was first described in the U.S.A. in 1925 on corn in Alexander County, IL. 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. 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. Photo: N. Kleczewski, 531 South College Avenue Gray leaf spot (GLS) is a foliar disease of corn caused by the fungus Cercospora zeae-maydis. These spores can easily travel through water to young plants, often infecting the plants lower leaves first. Figure 1. With time lesions can coalesce and form large necrotic areas and decimate the canopy (Figure 2). Albert E. Rossi, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. Entomology Image Gallery > Plant Diseases and Damage > Corn > Gray Leaf Spot. Gray leaf spot (GLS) has reached threshold levels in some corn fields in southwestern Iowa and a fungicide application should be considered for these fields. Gray Leaf Spot in Corn Gray leaf spot (G LS) is caused by the fungus Cercospora zeae-maydis. 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. 1A). Rainy and/or humid weather generally is most favorable to gray leaf spot. Cercospora zeae-maydis. "As rust pustules age and dry down, they are easily confused with gray leaf spot," Wise says. Crop rotation away from corn can reduce disease pressure, but multiple years may be necessary in no-till scenarios. Lesions of GLS elongating on corn leaf. Gray Leaf Spot of Corn: A Disease on the Move. Field corn represents the largest portion of the acreage grown. All corn hybrids, regardless of type, have some susceptibility to this disease. Foliar fungal diseases of primary concern in Michigan are northern corn leaf blight and gray leaf spot. No surfactant was included in applications made at V12. 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. 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. Distinct symptoms of GLS are rectangular, brown to gray necrotic lesions that run parallel to the leaf, spanning the spaces between the secondary leaf veins. 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. The fungal pathogens that cause these diseases survive on residue, so fields under minimum tillage and corn-on-corn rotations are at greatest risk. Companies use different scales for rating resistance, so be sure to check the scale. 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. The spores can be wind-blown or water-splashed onto the lower leaves. Gray Leaf Spot of Corn Gray leaf spot of corn is caused by the fungus Cercospora zeae-maydis. Gray leaf spot is now recognized as one of the most significant yield-limiting diseases of corn worldwide. Issue 98-23. Current data on tar spot indicate it likely doesn’t need to be controlled. The market is segmented into seed corn, field corn and specialty corns (e.g., high oil, high amylose and white corn). In the late spring, following periods of high humidity, the... Impacts of the Disease. Albert E. Rossi, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. much impact gray leaf spot will have on corn production. At NERF, an application was made based on the Tarspotter Appthat indicated a high risk of tar spot occurring. In years where disease risk is high or growers have planted susceptible hybrids in no till fields, fungicides may be considered. Cropping systems with reduced- or no-till and/or continuous corn are at higher risk for gray leaf spot outbreaks. Mature lesions are much more diagnostic and easier to distinguish from other common foliar diseases; they are long, grey to tan in color, and rectangular (Figure 1). Newark, DE 19716 Signs of Gray leaf spot are often first noticed on the lower leaves. 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. College of Agriculture & Natural Resources, 531 South College Avenue GLS lesions begin as small necrotic spots with chlorotic halos. Eight products at various application timings were evaluated (Table 1). © 2020 Corteva. In minimum tillage fields with a history of GLS, symptoms can occur on the lower leaves prior to tasseling. Under some conditions lesions may occur on stalks [2]. Gray leaf spot is one of the most important foliar diseases of corn and it is caused by Cercospora zeae-maydis. Under favorable environmental conditions spores are produced on foliar lesions and spread to upper leaves and other plants. Th… 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 of corn is caused by the fungus Cercospora zeae-maydis. Gray Leaf Spot: Corn Farmers' Biggest Rival As every veteran corn producer knows, corn is susceptible to a myriad of foliar fungal diseases . The fungus does not grow well on non-host residues. Planting hybrids with a high level of genetic resistance can help reduce the risk of yield loss due to gray leaf spot infection. 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. As the lesions expand, large areas of leaf tissue can be destroyed (Figure 2). Effective management of Gray leaf spot involves the use of resistant hybrids, rotation with non-hosts, and residue management. Gray leaf spot of corn is caused by a fungal pathogen Cercospora zeae-maydis (Syn. Plant Dis. Gray Leaf Spot. Gray Leaf Spot is a fungus found in corn nearly every growing season. Most fungicides provide protection for an average of 21-28 days. 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. 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. During the growing season, foliar fungicides can be used to manage gray leaf spot outbreaks. This NebGuide discusses the . 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. Gray leaf spot severity is unpredictable and multiple factors should be considered when making the decision to use fungicides to control Gray leaf spot.

gray leaf spot corn

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