Northern corn leaf spot is favored by high humidity and warm weather. And, we’re monitoring low level development of gray leaf spot and northern corn leaf blight. 0000214226 00000 n 0000213748 00000 n 0000211886 00000 n Corn grey leaf spot can be an extremely devastating disease as potential yield losses range from 5 to 40 bushels/acre. 0000199581 00000 n 0000199239 00000 n <<18C2D1B427EF2E4F8DC800A03A6A6554>]>> Percentage ear Leaf area affected by early dent stage (r5) approximate Yield Loss 5% or less 0-2% 6-25% 2-10% 25-75% 5-20% 75-100% (leaf death) 15-50% Managing the disease Preventative management strategies can reduce econom-ic losses due to gray leaf spot. 0000003933 00000 n 0000212163 00000 n 0000003165 00000 n The spores can be wind-blown or water-splashed onto the lower leaves. If you find ANY of foliar fungal diseases (e.g., gray leaf spot, northern corn leaf blight, northern corn leaf spot, southern rust on corn; frogeye leaf spot, soybean rust on soybean) in these at risk fields, spray. Numerous fields with significant levels of this disease have been reported in the past week. When the temperature is in the high 90s and grass is too wet to mow at 11:30 a.m., scout gray leaf spot. Gray Leafspot on Corn 0000195758 00000 n Grey leaf spot (GLS) is a foliar fungal disease that affects maize, also known as corn.GLS is considered one of the most significant yield-limiting diseases of corn worldwide. 0000159528 00000 n �r�O��$�.�#��w���3�OX�{{!�;I�O(Yda��\���i��a꫕S_0h�����ݛ�� 2��u�%�I�y���:j�z�ܡ������,+����W�r>����z���X�L8?�O��)O���1��w�keSr!��~��dCo �yq��h���� .��>����sh�t:�&�&ƠaUCJ$F���A/�G�_7����˫�Y���%�p�^V��ò������ 0000216345 00000 n This NebGuide discusses the symptoms, impacts and management of this disease. He added that tar spot has also been found in Ontario, Canada and an isolated area of Pennsylvania. For now, however, the threshold stands. 0000213365 00000 n As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). Those black spots are more than unsightly -- they're stealing corn from you. startxref 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. If conditions favor disease development, economic losses can occur. 0000003303 00000 n �*��)���G�%i�pzr�1X�{�*x��P���]��~ This threshold is being reevaluated because of the new hybrids and fungicide products that have been developed since then. Statewide, yield losses can average 20 to 30 percent on susceptible hybrids. 0000199918 00000 n Extended periods of leaf wetness (13 hours) allow infection of leaves. Gray leaf spot is also active in the lower to mid canopy at multiple sites across the state. There are five known races of this fungus. 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 of Corn Gray leaf spot of corn 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. The spores can be wind-blown or water-splashed onto the lower leaves. endstream endobj 586 0 obj <>/Size 478/Type/XRef>>stream 0000199891 00000 n The spores can be wind-blown or water-splashed onto the lower leaves. Although research attempts have been made to establish a threshold, they have not been successful likely because the disease triangle drives disease development and even the best pathologist has little say in weather conditions. Gray leaf spot and yield losses in corn. endstream endobj 479 0 obj <. 0000214910 00000 n In the past week I have started to see some corn leaf diseases, specifically Gray Leaf Spot (GLS), in many corn fields. 0000215163 00000 n Smith said gray leaf spot and tar spot were major 2020 soybean diseases, with both of them starting early in the season and moving slowly due to hot temperatures. 0000066745 00000 n 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). [�4�G;��C�:f*��&ay,2�������H(�g �(f#�e0 �����x�e���G3�L�ՈLœ"ѱ� ���cI�`%�cM�)�/z�Y�i�*IBխ���y���"�aQEH��K(��Hb�h:HR��$�д�4jah�)a*ل����B8�#�G�c*����/ Frances M. Latterell, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. These leaves contribute at least 75 percent of the carbohydrate content of the ear. ��l�4 ��P}Ie([�%\�\�g��ؠ � 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. 0000007636 00000 n Gray leaf spot does not occur on a widespread, annual basis in Michigan. 0000002563 00000 n much impact gray leaf spot will have on corn production. Gray leaf spot, caused by the fungus Cercospora zeae-maydis, occurs virtually every growing season. At higher disease levels, even greater … Tar spot did begin to move more quickly in late summer as temperatures cooled down in some areas, especially those with irrigation. 0000216084 00000 n 0000196607 00000 n 0000194833 00000 n Corn is … �@�/���R�&�f;����|�kQ�[�`3QH�YOF�>���l��eL�(��)ۇ�j>Y�&��}�__C $�����4©�lw�' ��a핫�O�G܏m�B����}�'�;;(R��{�7��f��������T�����1(1����L!��Դ��W�M%d�8�\�oj�'|�����x����3J�^�V2�"٢��������=:4l[I0�: 0000215563 00000 n Gray leaf spot is considered by many to be the greatest disease threat to corn in the world, and susceptibility is widespread across most all corn hybrids. h�b```c``v��>� �� 587 0 obj <>stream 0000005945 00000 n Gray leaf spot of corn, caused by the fungus Cercospora zeae-maydis, is currently the most serious foliar corn disease in Kansas. Although there are several races of the fungus that cause disease, Race 3 most likely causes the greatest impact in New York State. 0000215404 00000 n 0000066476 00000 n 0000195419 00000 n It is going to be extremely important to be out scouting, especially if you are trying to make a decision on a fungicide application. Deciding whether to apply fungicide seems straightforward, but not every corn field may need fungicide to manage gray leaf spot, she says. 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. Northern corn leaf spot caused by the fungus Cochliobolus carbonum has become more prevalent with the greater use of no-till systems. 0000214283 00000 n 0000212598 00000 n Careful product selections and timely applications will provide the most effective … It is going to be extremely important to be out scouting, especially if you are trying to make a decision on a fungicide application. For physoderma, an early application of fungicide when needed can improve yield and standability through harvest. Gray Leaf Spot of Field Corn. nomic threshold is to treat when 5% of the corn plants have either unhatched egg masses or larvae are present on the plant but before they burrow into the ear. The probability of yield increase with a fungicide application is higher when more high-risk factors for gray leaf spot development are applicable, especially with an expected yield greater than 200 bushels and a high corn price. The GLS has been seen in both both corn/corn on corn after soybean rotations. K��YQe�m읳_�>辅:�����4d-��ը���I����w̲�"D@*��V��Y��J`���2 >��J2hq��))���~��6�TM�����'�=�K��g�ޡ�L��4[�� �: Symptoms first appear on lower leaves about two to three weeks before tasseling. Both gray leaf spot and northern corn leaf blight are also active in the lower canopy of corn across the state. Producers can also use foliar fungicides when the economic threshold is exceeded. Each disease has an economic threshold. Northern corn leaf spot, also known as Carbonum leaf spot, is caused by the fungus Bipolaris zeicola. As a reminder, GLS is also caused by a fungus (Cercospora zeae-maydis) that survives in infected plant debris from the previous season(s).It consistently begins on the lower leaves and continues to move higher on the plant as long as weather conditions are favorable. In corn, the threshold for gray leaf spot (GLS), developed in the mid-1990s, consists of lesions on the third leaf below the ear leaf or higher occurring on 50% of the plants at tasseling. Warmer weather favors gray leaf spot, while cooler weather favors northern corn leaf blight. Hence, irrigated fields would tend to provide a … 0000213179 00000 n 3. Today, the disease has expanded to Delaware, Illinois, Indiana, Iowa, Maryland, Missouri, Ohio, Pennsylvania and west Tennessee. Management approaches that include hybrid selection, residue management, crop rotation and timely fungicide applications can be … As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). Most fields do not immediately need a fungicide application for disease management purposes. 0000006412 00000 n Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison Treating field corn, for grain, with fungicide has become a common practice in the Midwest. As you can see there was plenty of disease on this leaf. "Research in Indiana indicates that strobilurin and strobilurin/triazole premix fungicides are most effective at preventing yield loss when applied in response to disease presence, and at the tasseling to early silking (VT-R1) growth stage," she says. 0000000016 00000 n Typical lesions are rectangular with straight edges. 0000197137 00000 n Randomized complete block design with 4 replications was used. Two later-season diseases that can highly affect corn are tar spot and southern rust. Most fungicides provide protection for an average of 21-28 days. It is going to be extremely important to be out scouting, especially if you are trying to make a decision on a fungicide application. Early lesions are small, necrotic spots with yellow halos that gradually expand to full-sized lesions. 0000212888 00000 n Figure 3. 0000211821 00000 n There are five known races of this fungus. �HYd|56��$�>릓�Y�>��q&a�}'��4�d�����l�����r?��q>�+.��Wg��d��\QY�,�����H��/�2*��k��� Several fungicides are commercially available for use on corn for the control of gray leaf spot (Table II). Field trials have shown potential yield losses from gray leaf spot range from 5 to 40 bu/A. 67:842. Begin scouting for gray leaf spot in corn about 2 weeks before expected tassel emergence. 0000195934 00000 n When it does occur, it is more likely to be found in susceptible hybrids grown in corn after corn or in no till situations and is favored by high humidity. 0000196879 00000 n When it does occur, it is more likely to be found in susceptible hybrids grown in corn after corn or in no till situations and is favored by high humidity. Approximately one in two plants are infected, and corn is at growth stage VT/R1. Infection of corn leaves and disease development are favored by warm (80s°F), humid (>90% for 12+ hours) weather.” Generalized calendar of events for : common diseases in WI corn: Timings shown when the disease is typically visible and are approximate, varying according to location within the state. Photo by Doug Jardine, K-State Research and Extension . 0000214022 00000 n Northern corn leaf blight. 0000215347 00000 n Yield-impacting diseases you can see at V10 to V12 include physoderma, northern corn leaf blight and gray leaf spot. 0000212446 00000 n 0000004619 00000 n 0000212241 00000 n �" �j�I�{�u*�c�~����V���=${��p;��~9e3~��˗M�/PN�k~��gú�����)�1��ĺ-uVwtd�7?�����Z�+��~���7��~#�Q�n']GHR��#mmG���X|a�Vu�ݤI� ;I��'7��-��7M�?Ȯ�a�=�� �N�e�u���۴�'�%R)�#���?N����w�r�U�������UZ����~��i���� �/�b�݈�G������M���Q�]�� 0000214432 00000 n 0000009145 00000 n Gray Leaf Spot of Corn Causing Concern in Illinois. 0000009031 00000 n Hence, irrigated fields would tend to provide a better environment for the disease than non-irrigated fields. Field corn represents the largest portion of the acreage grown. Northern corn leaf spot, also known as Carbonum leaf spot, is caused by the fungus Bipolaris zeicola. 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 is also active in the lower to mid canopy at multiple sites across the state. Gray leaf spot may develop when temperatures are between 70 and 95°F, but the fungus also requires at least 14 hours of continuous leaf wetness in order to initiate infection. Click image to enlarge. Gray Leaf Spot of Corn: A Disease on the Move. No. 0000002976 00000 n Gray leaf spot (GLS) has the potential to limit corn yields if weather is favorable for disease development around VT-R1 and throughout the early reproductive stages. 0000016968 00000 n Northern corn leaf blight prefers cooler temperatures through grain fill. “Spores are dispersed by wind and splashing water. It may be freely reprinted with customary crediting of the source. 0000216233 00000 n 62 0 obj <> endobj 114 0 obj <>/Filter/FlateDecode/ID[<05373866A66744AF81E675383376AE2F>]/Index[62 121]/Info 61 0 R/Length 204/Prev 483367/Root 63 0 R/Size 183/Type/XRef/W[1 3 1]>>stream Make sure to properly identify the disease. Most fields do not immediately need a fungicide application for disease management purposes. 0000011010 00000 n 0000011878 00000 n As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). “Start scouting early, and note size of lesions and where they’re located. 0000010382 00000 n The fungal disease causes lesions that lead to yellowing leaf tissue and reduced photosynthetic activity, causing shortened yield potential through smaller ears with fewer kernels. 0000004741 00000 n 0000215618 00000 n The fungus that causes gray leaf spot infects the corn plant during prolonged periods of warm weather between 75-80 degrees and at more than 90 percent relative humidity. 1 DMR, was carried out at Damnornsaduak, Ratchaburi province during December 1994-February 1995. �x���O��{��_����@6�݆��E�-�){=�6����G!���-c//�x��x5�|aR��1�r�\����[��ag��,�N=;�v+GA6K��P��R�-�o@Q�A0�[��%Y�dW�š�8������#.-O&��ㆊ/��^��s~ �.�zs?n���a��� ����Z�"�`�`���ş�P��`2��y���j�VW�3�?�&@0jN�"/��̘2���w���%埼�#鶰u�o�'H�5��u�b���ծ��� Lesions from Northern corn leaf blight in no-till corn in corn-soybean rotations in east central Nebraska. Figure 7­7. 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. 0000215790 00000 n 0000213691 00000 n There are currently no thresholds for Gray leaf spot although some researchers have developed general estimates of the disease on corn yield (Table 1). The market is segmented into seed corn, field corn and specialty corns (e.g., high oil, high amylose and white corn). 0000212072 00000 n %PDF-1.6 %���� 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. Issue 98-23. High residue farming allows the gray leaf spot pathogen to build up in corn residue over time. Before 1970, corn grey leaf spot was not prevalent in the United States, however the disease spread during the mid part of the decade throughout low mountain regions of North Carolina, Kentucky, Tennessee, and Virginia. This threshold is being reevaluated because of the new hybrids and fungicide products that have been developed since then. We provide evidence for structural and detoxification-related mechanisms … “Spores are dispersed by wind and splashing water. Author Summary Gray leaf spot (GLS), a necrotrophic, foliar fungal disease of maize, contributes to maize yield losses worldwide. 0000066815 00000 n As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). Gray leaf spot of corn. 0000195688 00000 n Weather and other conditions have been favorable recently for development of gray leaf spot in Illinois. All corn hybrids and inbreds are susceptible to gray leaf spot in varying degrees. Gray Leaf Spot is an economically important disease in many midwestern and eastern corn belt states. 0000214169 00000 n 0000214730 00000 n Lesions of GLS elongating on corn leaf. Gray Leaf Spot Now that harvest is completed, it is time to start thinking about next year and making seed corn selection decisions. Click image to enlarge. 0000006829 00000 n Because gray leaf spot reduces an ear’s photosynthetic 0000215845 00000 n 0000012721 00000 n 0000212542 00000 n Multiple lesions from Northern corn leaf blight on lower leaf in a continuous corn field in east central Nebraska. 0000007383 00000 n In growing seasons when these conditions prevail, the risk for disease development increases. Study on the economic threshold level of the corn leaf aphid on super sweet corn, Composit No. 0000215053 00000 n Mature lesions are tan to gray and expand linearly between leaf veins giving a rectangular shape. 0000213308 00000 n Figure 1. 0000216139 00000 n 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. This allows for a bit of risk adversity on the part of the producer when determining the need for fungicide applications. Lesions can grow together and kill entire leaves. 0000008165 00000 n %PDF-1.6 %���� When lesions are at the ear leaf or above prior to flowering, the potential for yield loss is present. There are two fungal pathogens that cause GLS: Cercospora zeae-maydis and Cercospora zeina. Gray leaf spot (GLS) is a foliar disease of corn caused by the fungus Cercospora zeae-maydis. Both gray leaf spot and northern corn leaf blight are also active in the lower canopy of corn across the state. h���1a��y�qW'a����dfS&�(�e%���l��E��&���:����0������{��9�"�� 0000213877 00000 n 0000213580 00000 n 0000214112 00000 n Increased corn-on-corn acres, especially when economic conditions favor corn over other crops combined with modern tillage practices, can lead to more corn residue in fields. 0000216289 00000 n 0000004498 00000 n Currently, it is not widespread but when you are out scouting look for these lesions on the leaves. 0000003744 00000 n 0000213044 00000 n ... Gray leaf spot on corn. trailer Weather. Unresolved Issues for gray leaf spot Corn is grown throughout Nebraska on over 8 million acres of land; approximately 5 million acres are irrigated. A three-spray schedule of 0.01 percent imidacloprid at … These thresholds do not apply to fungicide use in field corn. Yield loss is primarily incurred when the top eight to nine leaves above the ear become diseased. 0000212832 00000 n Gray leaf spot overwinters in and on corn debris left above and on the soil surface. Albert E. Rossi, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. 0000214339 00000 n Gray Leaf Spot – Corn. 0000010409 00000 n This article is in the public domain and not copyrightable. �Ŋ�޹�X����\5!��Ud���}#�v��Z��T.���n�D�壝�h���UO�����~ ���C Gray Leaf Spot of Field Corn. Several fungicides are available to help manage southern rust, tar spot, gray leaf spot, and other leaf diseases with a recommended application occurring at late vegetative stages through R1 for most of these foliar diseases. %%EOF Gray leaf spot. �E�WBCВɈƤDt�ך)ᤗTE� ea�������?����@����@&�M��fb����\x��ڲN�� tJ@��e�ު3|C� �Wttt000�Ch�r � P1:6 �$�ڴ������gd�h�nPU��7�������1>P\�����-�aCw�,у�/�mP(�ff�ePmId=�~BB���W�u � 6+X�01�b]��`�`�G�i%�)�Op��/>(� ��K9�X �D� WJ� endstream endobj 63 0 obj <>>> endobj 64 0 obj <>/ExtGState<>/Font<>/ProcSet[/PDF/Text/ImageC]/Shading<>/XObject<>>>/Rotate 0/TrimBox[0.0 0.0 612.0 792.0]/Type/Page>> endobj 65 0 obj <>stream 0000014508 00000 n It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. 0000013616 00000 n And, we’re monitoring low level development of gray leaf spot and northern corn leaf blight. Gray leaf spot overwinters in and on corn debris left above and on the soil surface. It was initially detected in the southeastern coastal corn growing states of Virginia, Georgia and the Carolinas in the 1920s. “In any case, you’re back to scouting and seeing what is in the field,” Schmidt says. Gray leaf spot does not occur on a widespread, annual basis in Michigan. Treatments were five different applications included with check (untreated). 0000216029 00000 n The lesions appear on the oldest leaves first, and progress upward. �4��~��j�{l֎y;3��{D�>A�. Northern Corn Leaf Blight Continues, Gray Leaf Spot Starts in 2015 Share Tweet Email. It is occasionally seen in the lower canopy during periods of high humidity and moderate temperatures. �c;ԡA=2/2��,h��G:����ߎ�Gi�ɆusCX����S�lC���蓧+�M��np�,p�.�=��ϕ9;�gU�Q���f�����r��7br=�Qg*�h튱���~���+� �{!� endstream endobj startxref 0 %%EOF 182 0 obj <>stream Bayer Crop Science LP 1,052 views. Gray leaf spot (GLS) has the potential to limit corn yields if weather is favorable for disease development around VT-R1 and throughout the early reproductive stages. xref Gray leaf spot (GLS), caused by Cercospora zeae-maydis, is an important foliar disease of maize (Zea mays L.) worldwide, resistance to which is controlled by multiple quantitative trait loci (QTL). Gray Leaf Spot, or GLS, is only known to affect corn. 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. 0000005339 00000 n Races 2 and 3 are the most common in the Midwest. From that initial find, the disease reached economic threshold levels by 1992. 0000199511 00000 n Symptoms seen on corn include leaf lesions, discoloration (), and foliar blight. 0000211370 00000 n Crop Observation and Recommendation network. 0000010240 00000 n Management approaches that include hybrid selection, residue management, crop rotation and timely fungicide applications can be … It is occasionally seen in the lower canopy during periods of high humidity and moderate temperatures. The symptoms of the disease vary with the severity of the infection and stage of corn development at which the infection occurred. 0000009257 00000 n Various estimates place the leaf area damage in the range of 10 to 25 percent on the bottom four leaves before economic losses can be expected to occur. Any factor that increases the amount of leaf wetness will increase gray leaf spot development such as extended periods of cloud cover, improper irrigation timing / frequency, or extended rainfall events. Field history. Northern corn leaf spot of corn. 0000214577 00000 n Gray Leaf Spot Now that harvest is completed, it is time to start thinking about next year and making seed corn selection decisions. 0000212000 00000 n Rainy and/or humid weather generally is most favorable to 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. The picture below was taken from a field that was corn after soybeans and was not pollinating yet. 0000212731 00000 n 2:26. Growing Prevalence and Risk. You don't want to be spraying a … Both gray leaf spot and northern corn leaf blight are also active in the lower canopy of corn across the state. 0000006579 00000 n Purdue University experts are seeing gray leaf spot lesions on some susceptible corn hybrids in Indiana, and they are encouraging farmers to scout fields to assess the level of disease. 0000212988 00000 n High relative humidity (>90%) can lead to increased disease. Applications made too early may mean their protection has worn off before diseases reach critical levels. Other diseases, such as Gray Leaf Spot (GLS), are also developing. Plant Dis. 0000015356 00000 n 0000195907 00000 n >�%��5��=Z$n�&�rD~%���'�k�`�a"��p��j̀�g�3!��O��` Identifying Gray Leaf Spot in Corn - Duration: 2:26. In corn, the threshold for gray leaf spot (GLS), developed in the mid-1990s, consists of lesions on the third leaf below the ear leaf or higher occurring on 50% of the plants at tasseling. Gray leaf spot is characterized by rectangular lesions that are 1-2 inches in length and cover the entire area between the leaf veins. 0000003806 00000 n It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. 0000215108 00000 n Gray leaf spot (GLS) is a common fungal disease in the United States caused by the pathogen Cercospora zeae-maydis in corn. 0000016107 00000 n It was first identified in the state in 1989 in the Republi-can River valley. �u�{�tlq��(T����fVI� �1�-s��;;J�,N(?a�P,B�Ģ��X$:�ʑ@� h��Zks�6�+��L'�'��Ɍ-׉��FiܮFӡ%�f#��H�q��P6eK��������=��"�,�,�7�"M��IK���X�H 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. 0000067308 00000 n 478 110 0000214785 00000 n x�bbRa`b``Ń3� ���ţ�1�a� -�� Gray leaf spot overwinters in and on corn debris left above and on the soil surface. 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. 0000213450 00000 n In some cases, gray leaf spot can limit yield up to 5 to 40 bushels of corn per acre. 0000212390 00000 n 0 Gray leaf spot overwinters in and on corn debris left above and on the soil surface. 478 0 obj <> endobj 0000008410 00000 n (Figures 1-3 by Nathan Mueller) Figure 2. Numerous rectangular lesions caused by gray leaf spot. 0000214633 00000 n 0000004863 00000 n Races 2 and 3 are the most common in the Midwest. From its first appear-ance in Kansas in the Republican River Valley in 1989, 0000214488 00000 n corn diseases, it is recommended that suspicious samples be sent to the Arkansas Plant Health Clinic in Fayetteville for proper identification. 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. Department of Plant Pathology MF2341 Corn Diseases Gray Leaf Spot of Corn Gray leaf spot of corn is caused by the fungus Cercospora zeae-maydis. 0000213965 00000 n 0000212298 00000 n ��w��|(_��S��b~pFFTmzA]*A#����g}՗R"ѷ�"�7&H�7�����B����s��q� L�I�㾶j���(g|���4]���'% ;J�0(Ry?���K1,GХ;A_������I.+r�X��5�Z��߻F��b����A~q�����~Q�g��lF��G�����8��y�]g�����vz���Y��|��H-�E~���j�����g��Ux�s��a6 Is there a threshold for Northern corn leaf blight (or other diseases for that matter)? The spores can be wind-blown or water-splashed onto the lower leaves. We identified and characterized regions of the maize genome that confer resistance to GLS and gained insight into the mechanisms associated with these quantitative trait loci (QTL). Gray Leaf Spot is a fungus found in corn nearly every growing season. Northern Leaf Blight. Gray Leaf Spot – Corn 6-15 1. Symptoms are gray, elongated lesions 1 to 6 inches long (Figure 6). �Q�8f>Ng���5�w������w?�|Vմ>�ԇ�ԁ���E ,|[���z�� m�WU߁ S&�x�N�2��.D ��:�/��#&�E "@����7PO�r8�>�3 Hm�����p0^�+=ؑD,?�]� 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. Gray leaf spot (GLS) can be one of the most significant diseases on corn in the Midwest. 0000197164 00000 n The disease is first detectable as small grayish lesions on the lower leaves, which run parallel to the veins. 0000196949 00000 n With so many fungicide programs and formulations, and the re-emergence of yield-limiting corn diseases, like northern corn leaf blight (NCLB) and gray leaf spot (GLS), foliar fungicide application has …
2020 gray leaf spot corn threshold