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. Wise, K. 2010. Gray Leaf Spot at Threshold Levels 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. This article is about a disease in grasses other than maize, the disease is the same in rice as it is in maize, Corn grey leaf spot (Magnaporthe grisea) Gray leaf spot (GLS) is a foliar fungal disease that affects grasses. Entire leaves can be killed when weather conditions are favorable, and rapid disease progression causes lesions to merge. The fungus survives in corn residue, and, consequently, the disease is often more severe in corn following corn. Because early lesions are ambiguous, they are easily confused with other foliar diseases such as anthracnose leaf blight, eyespot, or common rust. It was initially detected in the southeastern coastal corn growing states of Virginia, Georgia and the Carolinas in the 1920s. GLS lesions begin as small necrotic spots with chlorotic halos. Gray Leaf Spot in Corn Gray leaf spot (G LS) is caused by the fungus Cercospora zeae-maydis. In the 1960s and 1970s, the disease became of concern in the eastern United States. Lesions of GLS elongating on corn leaf. 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 symptoms of the disease vary with the severity of the infection and stage of corn development at which the infection occurred. And she warns that many fields contain common rust. Rectangular, gray to tan lesions are characteristic to gray leaf spot on corn. Signs of Gray leaf spot are often first noticed on the lower leaves. Patrick Lipps, 1998. 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. Basic requirements Corn is best grown in warm, tropical and sub-tropical regions as it requires warm soils to develop optimally. It can be confused with other foliar diseases of corn. Applications made too early may mean their protection has worn off before diseases reach critical levels. Damage can be more severe when developing lesions progress past the ear leaf around pollination time. Frances M. Latterell, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. From its first appear-ance in Kansas in the Republican River Valley in 1989, Figure 2. These spores can easily travel through water to young plants, often infecting the plants lower leaves first. 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. Gray leaf spot is now recognized as one of the most significant yield-limiting diseases of corn worldwide. 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. corn diseases, it is recommended that suspicious samples be sent to the Arkansas Plant Health Clinic in Fayetteville for proper identification. … Severe outbreaks of Gray leaf spot can result in losses resulting from  reduced photosynthesis and grain fill [2]. Under some conditions lesions may occur on stalks [2]. 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 fungus will usually survive for no more than two years; often, one year away from corn allows for substantial reduction in risk. Grey leaf spot (GLS) is a foliar fungal disease that affects maize, also known as corn. 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. Gray leaf spot is a persistent and economically damaging fungal disease of corn across the United States. Other factors, such as hybrid susceptibility and favorable weather for pathogen infection greatly impact the impact of Gray leaf spot on corn production. Gray leaf spot is caused by the fungus Cercospora zeae-maydis. The disease was first reported in Illinois in 1924, and has increased in prevalence throughout corn growing regions since 1988. This article is in the public domain and not copyrightable. All corn hybrids and inbreds are susceptible to Gray Leaf Spot (GLS). Because a decrease in functioning leaf area limits photosynthates dedicated towards grainfill, the plant might mobilize more carbohydrates from the stalk to fill kernels. Gray leaf spot develops first on lower leaves and may spread upward to the highest leaf. Plant Dis. Gray leaf spot is one of the most common foliar diseases in Delaware corn and can significantly reduce corn yields under favorable conditions. Photo: N Kleczewski. When temperatures begin to increase during the spring, the fungus will produce spores. 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. Spores from both of these pathogens can either be splashed up onto foliage or deposited by the wind. Numerous rectangular lesions caused by gray leaf spot. It should b… Under the proper circumstances significant loss photosynthetic area of the canopy occurs, resulting in reduced yield. Cultural practices reduce local levels of inoculum, which may help reduce disease progress and impact on yield. Gray leaf spot overwinters in and on corn debris left above and on the soil surface. 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. Gray leaf spot (GLS) is a foliar disease of corn caused by the fungus Cercospora zeae-maydis. “Spores are dispersed by wind and splashing water. Table 1. Gray Leaf Spot of Corn Gray leaf spot of corn is caused by the fungus Cercospora zeae-maydis. The most severe GLS was observed at SWRF, where the mean GLS severity in the non-sprayed check was 13.8%. Madden, University of Delaware Newark, DE 19716 USA. 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. Corn plants susceptible and resistant to gray leaf spot; Gray leaf spot on inbred ear leaf; Gray leaf spot … In growing seasons when these conditions prevail, the risk for disease development increases. It may be freely reprinted with customary crediting of the source. Gray Leaf Spot of Corn: A Disease on the Move. Gray Leaf Spot. Crop Observation and Recommendation network. (Wise, 2019). 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. As infection progresses, lesions begin to take on a more distinct shape. Unresolved Issues for gray leaf spot Corn is grown throughout Nebraska on over 8 million acres of land; approximately 5 million acres are irrigated. Introduction. Northern corn leaf blight can be identified by the distinctive lesions that form on the leav… In order to cause severe yield reduction the disease must damage leaves around the silking growth stage. There are numerous hybrids with resistance to this disease, although none are immune. Gray leaf spot is favored by wet humid weather as often found in valley microclimates. It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. Burying residue as little as 10-cm below the surface can greatly reduce primary infection levels. Gray leaf spot (GLS) (Figure 1) caused by Cercospora zeae-maydis is considered the world’s most yield-limiting disease on corn. Gray leaf spot is due to a fungus called Cercospora zeae-maydis, and can be economically damaging to corn crops. Introduction. 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. Mature lesions are tan to gray and expand linearly between leaf veins giving a rectangular shape. All corn hybrids, regardless of type, have some susceptibility to this disease. 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. Estimated yield loss based off of percent of tissue infected by gray leaf spot (Lipps, 1998). No surfactant was included in applications made at V12. Jennifer M. Rees, Extension Educator Tamra A. Jackson, Extension Plant Pathologist. All corn hybrids and inbreds are susceptible to gray leaf spot in varying degrees. Gray leaf spot is one of the most important foliar diseases of corn and it is caused by Cercospora zeae-maydis. Additionally, it is favored in situations with reduced tillage and continuous corn. At NERF, an application was made based on the Tarspotter Appthat indicated a high risk of tar spot occurring. Gray leaf spot (GLS) (Figure 1) caused by Cercospora zeae-maydis is considered the world’s most yield-limiting disease on corn. Lesions of GLS elongating on corn leaf. In the late spring, following periods of high humidity, the... Impacts of the Disease. Newark, DE 19716 Gray leaf spot of corn is being reported across the state. Gray Leaf Spot and Northern Corn Leaf Blight. 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. Predicted yield losses resulting from Gray leaf spot. This NebGuide discusses the . Effective management of Gray leaf spot involves the use of resistant hybrids, rotation with non-hosts, and residue management. This article will discuss how to diagnose Gray leaf spot, the disease cycle of the pathogen, impacts of the disease, and management recommendations. 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