gray leaf spot corn threshold

�4��~��j�{l֎y;3��{D�>A�. 0000215563 00000 n "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. Gray leaf spot (GLS) can be one of the most significant diseases on corn in the Midwest. Gray Leaf Spot of Corn Gray leaf spot of corn is caused by the fungus Cercospora zeae-maydis. 0000212163 00000 n Field corn represents the largest portion of the acreage grown. 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 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. Lesions of GLS elongating on corn leaf. ea��?��@��@&�M��fb��\x��ڲN�� tJ@��e�ު3|C� �Wttt000�Ch�r � P1:6 �$�ڴ��gd�h�nPU��7��1>P\��-�aCw�,у�/�mP(�ff�ePmId=�~BB��W�u � 6+X�01�b]��`�`�G�i%�)�Op��/>(� ��K9�X �D� WJ� endstream endobj 63 0 obj <>>> endobj 64 0 obj <>/ExtGState<>/Font<>/ProcSet[/PDF/Text/ImageC]/Shading<>/XObject<>>>/Rotate 0/TrimBox[0.0 0.0 612.0 792.0]/Type/Page>> endobj 65 0 obj <>stream 0000007636 00000 n Various estimates place the leaf area damage in the range of 10 to 25 percent on the bottom four leaves before economic losses can be expected to occur. All corn hybrids and inbreds are susceptible to gray leaf spot in varying degrees. K��YQe�m읳_�>辅:��4d-��ը��I��w̲�"D@*��V��Y��J`��2 >��J2hq��))��~��6�TM��'�=�K��g�ޡ�L��4[�� : Both gray leaf spot and northern corn leaf blight are also active in the lower canopy of corn across the state. much impact gray leaf spot will have on corn production. Click image to enlarge. 0000003303 00000 n This threshold is being reevaluated because of the new hybrids and fungicide products that have been developed since then. 0000215790 00000 n 0000213748 00000 n 0000212598 00000 n %PDF-1.6 %�� The GLS has been seen in both both corn/corn on corn after soybean rotations. The lesions appear on the oldest leaves first, and progress upward. Gray leaf spot overwinters in and on corn debris left above and on the soil surface. ... Gray leaf spot on corn. 0000214633 00000 n 0000213044 00000 n Numerous rectangular lesions caused by gray leaf spot. [�4�G;��C�:f*��&ay,2��H(�g �(f#�e0 ��x�e��G3�L�ՈL"ѱ� ��cI�`%�cM�)�/z�Y�i�*IBխ��y��"�aQEH��K(��Hb�h:HR��$�д�4jah�)a*ل��B8�#�G�c*��/ Gray Leaf Spot of Field Corn. 0000000016 00000 n Identifying Gray Leaf Spot in Corn - Duration: 2:26. 0000214910 00000 n 0000214169 00000 n Because gray leaf spot reduces an ear’s photosynthetic And, we’re monitoring low level development of gray leaf spot and northern corn leaf blight. 0000008165 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. 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. High relative humidity (>90%) can lead to increased disease. From that initial find, the disease reached economic threshold levels by 1992. If conditions favor disease development, economic losses can occur. 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. 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 leaf spot does not occur on a widespread, annual basis in Michigan. Warmer weather favors gray leaf spot, while cooler weather favors northern corn leaf blight. 0000003806 00000 n Both gray leaf spot and northern corn leaf blight are also active in the lower canopy of corn across the state. 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. Races 2 and 3 are the most common in the Midwest. 0000197137 00000 n Symptoms seen on corn include leaf lesions, discoloration (), and foliar blight. �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,?�]� Lesions from Northern corn leaf blight in no-till corn in corn-soybean rotations in east central Nebraska. 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). There are five known races of this fungus. Issue 98-23. For now, however, the threshold stands. 67:842. Gray Leaf Spot Now that harvest is completed, it is time to start thinking about next year and making seed corn selection decisions. 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. h��1a��y�qW'a��dfS&�(�e%��l��E��&��:��0��{��9�"�� 0000195758 00000 n 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 is a fungus found in corn nearly every growing season. 0000195934 00000 n Northern corn leaf spot of corn. endstream endobj 586 0 obj <>/Size 478/Type/XRef>>stream 0000216289 00000 n No. 0000214488 00000 n As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). Numerous fields with significant levels of this disease have been reported in the past week. And, we’re monitoring low level development of gray leaf spot and northern corn leaf blight. 2:26. Frances M. Latterell, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. Deciding whether to apply fungicide seems straightforward, but not every corn field may need fungicide to manage gray leaf spot, she says. Producers can also use foliar fungicides when the economic threshold is exceeded. Other diseases, such as Gray Leaf Spot (GLS), are also developing. 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. Gray leaf spot (GLS) is a common fungal disease in the United States caused by the pathogen Cercospora zeae-maydis in corn. Bayer Crop Science LP 1,052 views. h�b```c``v��>� �� 0000213450 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). Gray leaf spot overwinters in and on corn debris left above and on the soil surface. 0000195688 00000 n Figure 3. In the past week I have started to see some corn leaf diseases, specifically Gray Leaf Spot (GLS), in many corn fields. It is occasionally seen in the lower canopy during periods of high humidity and moderate temperatures. Extended periods of leaf wetness (13 hours) allow infection of leaves. Gray leaf spot of corn. 0000195907 00000 n 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. 0000197164 00000 n 0000012721 00000 n It was initially detected in the southeastern coastal corn growing states of Virginia, Georgia and the Carolinas in the 1920s. Randomized complete block design with 4 replications was used. 0000212832 00000 n Corn is … Gray Leaf Spot is an economically important disease in many midwestern and eastern corn belt states. Races 2 and 3 are the most common in the Midwest. Corn grey leaf spot can be an extremely devastating disease as potential yield losses range from 5 to 40 bushels/acre. h��Zks�6�+��L'�'��Ɍ-׉��FiܮFӡ%�f#��H�q��P6eK��=��"�,�,�7�"M��IK��X�H x�bbRa`b``Ń3� ��ţ�1�a� -�� Click image to enlarge. 0000215053 00000 n 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. Yield-impacting diseases you can see at V10 to V12 include physoderma, northern corn leaf blight and gray leaf spot. Gray leaf spot overwinters in and on corn debris left above and on the soil surface. 0000004741 00000 n Several fungicides are commercially available for use on corn for the control of gray leaf spot (Table II). As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). It is going to be extremely important to be out scouting, especially if you are trying to make a decision on a fungicide application. Gray Leafspot on Corn These thresholds do not apply to fungicide use in field corn. 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. Both gray leaf spot and northern corn leaf blight are also active in the lower canopy of corn across the state. 0000004619 00000 n 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. Make sure to properly identify the disease. 0000214339 00000 n 0000009031 00000 n Currently, it is not widespread but when you are out scouting look for these lesions on the leaves. 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. >�%��5��=Z$n�&�rD~%��'�k�`�a"��p��j̀�g�3!��O��` 0000004498 00000 n Applications made too early may mean their protection has worn off before diseases reach critical levels. 0000003165 00000 n 0000212241 00000 n For physoderma, an early application of fungicide when needed can improve yield and standability through harvest. 0000016107 00000 n At higher disease levels, even greater … Gray Leaf Spot – Corn 6-15 1. Gray leaf spot (GLS) is a foliar disease of corn caused by the fungus Cercospora zeae-maydis. �*��)��G�%i�pzr�1X�{�*x��P��]��~ �r�O��$�.�#��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�� Northern corn leaf spot is favored by high humidity and warm weather. Mature lesions are tan to gray and expand linearly between leaf veins giving a rectangular shape. As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). 1 DMR, was carried out at Damnornsaduak, Ratchaburi province during December 1994-February 1995. The spores can be wind-blown or water-splashed onto the lower leaves. 0000010240 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. Northern corn leaf blight prefers cooler temperatures through grain fill. 0000215163 00000 n Hence, irrigated fields would tend to provide a better environment for the disease than non-irrigated fields. 0000066745 00000 n 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. Gray Leaf Spot Now that harvest is completed, it is time to start thinking about next year and making seed corn selection decisions. It is occasionally seen in the lower canopy during periods of high humidity and moderate temperatures. (Figures 1-3 by Nathan Mueller) Figure 2. Growing Prevalence and Risk. Hence, irrigated fields would tend to provide a … The market is segmented into seed corn, field corn and specialty corns (e.g., high oil, high amylose and white corn). Management approaches that include hybrid selection, residue management, crop rotation and timely fungicide applications can be … Early lesions are small, necrotic spots with yellow halos that gradually expand to full-sized lesions. 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. 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. 0000006829 00000 n 0000066476 00000 n 0000213691 00000 n 0000211821 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. Lesions can grow together and kill entire leaves. 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 “In any case, you’re back to scouting and seeing what is in the field,” Schmidt says. 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. He added that tar spot has also been found in Ontario, Canada and an isolated area of Pennsylvania. 0000212446 00000 n �@�/��R�&�f;��|�kQ�[�`3QH�YOF�>��l��eL�(��)ۇ�j>Y�&��}�__C $��4©�lw�' ��a핫�O�G܏m�B��}�'�;;(R��{�7��f��T��1(1��L!��Դ��W�M%d�8�\�oj�'|��x��3J�^�V2�"٢��=:4l[I0�: Northern corn leaf spot, also known as Carbonum leaf spot, is caused by the fungus Bipolaris zeicola. Gray leaf spot (GLS) has the potential to limit corn yields if weather is favorable for disease development around VT-R1 and throughout the early reproductive stages. Gray leaf spot. %%EOF Today, the disease has expanded to Delaware, Illinois, Indiana, Iowa, Maryland, Missouri, Ohio, Pennsylvania and west Tennessee. In growing seasons when these conditions prevail, the risk for disease development increases. 0000212000 00000 n xref �" �j�I�{�u*�c�~��V��=${��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�]�� 0000007383 00000 n corn diseases, it is recommended that suspicious samples be sent to the Arkansas Plant Health Clinic in Fayetteville for proper identification. 0000002563 00000 n 0000212888 00000 n Figure 1. Gray Leaf Spot of Corn Causing Concern in Illinois. 0000196949 00000 n “Spores are dispersed by wind and splashing water. 0000213580 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. This threshold is being reevaluated because of the new hybrids and fungicide products that have been developed since then. 0000215618 00000 n 0000199918 00000 n 0000009257 00000 n Photo by Doug Jardine, K-State Research and Extension . 0000213365 00000 n �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 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. 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. Gray leaf spot is also active in the lower to mid canopy at multiple sites across the state. Rainy and/or humid weather generally is most favorable to gray leaf spot. 0000010382 00000 n As temperatures warm and humidity increases, spores are produced on the residue (Figure 3). Treatments were five different applications included with check (untreated). 0000003744 00000 n 0000199239 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. 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). 0000215404 00000 n 0000213965 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. Management approaches that include hybrid selection, residue management, crop rotation and timely fungicide applications can be … 0000010409 00000 n %PDF-1.6 %�� A three-spray schedule of 0.01 percent imidacloprid at … Northern Leaf Blight. Begin scouting for gray leaf spot in corn about 2 weeks before expected tassel emergence. Northern corn leaf spot caused by the fungus Cochliobolus carbonum has become more prevalent with the greater use of no-till systems. 587 0 obj <>stream Yield loss is primarily incurred when the top eight to nine leaves above the ear become diseased. 0000214022 00000 n 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. 0000006579 00000 n 0000015356 00000 n 0000216084 00000 n 0000004863 00000 n Gray Leaf Spot is a fungus found in corn nearly every growing season. 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. Weather and other conditions have been favorable recently for development of gray leaf spot in Illinois. Northern Corn Leaf Blight Continues, Gray Leaf Spot Starts in 2015 Share Tweet Email. Study on the economic threshold level of the corn leaf aphid on super sweet corn, Composit No. “Spores are dispersed by wind and splashing water. 0 478 110 0000214785 00000 n It was first identified in the state in 1989 in the Republi-can River valley. When lesions are at the ear leaf or above prior to flowering, the potential for yield loss is present. 0000214730 00000 n �E�WBCВɈƤDt�ך)ᤗTE� Those black spots are more than unsightly -- they're stealing corn from you. Northern corn leaf spot, also known as Carbonum leaf spot, is caused by the fungus Bipolaris zeicola. 0000066815 00000 n 0000005945 00000 n 0000211370 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. There are two fungal pathogens that cause GLS: Cercospora zeae-maydis and Cercospora zeina. 0000194833 00000 n The disease is first detectable as small grayish lesions on the lower leaves, which run parallel to the veins. 0000212988 00000 n 0000002976 00000 n 0000212390 00000 n Typical lesions are rectangular with straight edges. 0000212298 00000 n It may be freely reprinted with customary crediting of the source. This article is in the public domain and not copyrightable. �x��O��{��_��@6�݆��E�-�){=�6��G!��-c//�x��x5�|aR��1�r�\��[��ag��,�N=;�v+GA6K��P��R�-�o@Q�A0�[��%Y�dW��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�� 0000196607 00000 n �HYd|56��$�>릓�Y�>��q&a�}'��4�d��l��r?��q>�+.��Wg��d��\QY�,��H��/�2*��k�� 0000159528 00000 n Most fungicides provide protection for an average of 21-28 days. 0000195419 00000 n Gray Leaf Spot – Corn. Gray leaf spot and yield losses in corn. 0000006412 00000 n 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. Most fields do not immediately need a fungicide application for disease management purposes. 0000215108 00000 n 0000009145 00000 n 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. 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. Crop Observation and Recommendation network. 0000216029 00000 n 0000211886 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. 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. Is there a threshold for Northern corn leaf blight (or other diseases for that matter)? 0000214432 00000 n 0000196879 00000 n Figure 77. 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. Most fungicides provide protection for an average of 21-28 days. Gray leaf spot is characterized by rectangular lesions that are 1-2 inches in length and cover the entire area between the leaf veins. Field history. There are five known races of this fungus. 0000213877 00000 n trailer Gray Leaf Spot of Corn: A Disease on the Move. Northern corn leaf blight. It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. These leaves contribute at least 75 percent of the carbohydrate content of the ear. 0000003933 00000 n 0000013616 00000 n 0000212542 00000 n Field trials have shown potential yield losses from gray leaf spot range from 5 to 40 bu/A. High residue farming allows the gray leaf spot pathogen to build up in corn residue over time. <<18C2D1B427EF2E4F8DC800A03A6A6554>]>> Gray Leaf Spot, or GLS, is only known to affect corn. 3. 0000213179 00000 n Plant Dis. Careful product selections and timely applications will provide the most effective … Gray leaf spot of corn, caused by the fungus Cercospora zeae-maydis, is currently the most serious foliar corn disease in Kansas. Weather. 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 does not occur on a widespread, annual basis in Michigan. 0000214112 00000 n Tar spot did begin to move more quickly in late summer as temperatures cooled down in some areas, especially those with irrigation. Albert E. Rossi, Plant Disease Research Laboratory, USDA-ARS, Frederick, MD. Although there are several races of the fungus that cause disease, Race 3 most likely causes the greatest impact in New York State. Multiple lesions from Northern corn leaf blight on lower leaf in a continuous corn field in east central Nebraska. 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. ��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 Most fields do not immediately need a fungicide application for disease management purposes. Gray leaf spot is also active in the lower to mid canopy at multiple sites across the state. �u�{�tlq��(T��fVI� �1�-s��;;J�,N(?a�P,B�Ģ��X$:�ʑ@� Statewide, yield losses can average 20 to 30 percent on susceptible hybrids. 0000214577 00000 n Author Summary Gray leaf spot (GLS), a necrotrophic, foliar fungal disease of maize, contributes to maize yield losses worldwide. 0000011878 00000 n The spores can be wind-blown or water-splashed onto the lower leaves. “Start scouting early, and note size of lesions and where they’re located. Two later-season diseases that can highly affect corn are tar spot and southern rust. This allows for a bit of risk adversity on the part of the producer when determining the need for fungicide applications. 0000214283 00000 n ��l�4 ��P}Ie([�%\�\�g��ؠ � It is the most serious foliar disease of corn, not only in Kansas, but in the entire north central production region. 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. 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. Gray leaf spot, caused by the fungus Cercospora zeae-maydis, occurs virtually every growing season. 0000011010 00000 n The spores can be wind-blown or water-splashed onto the lower leaves. 0000216139 00000 n As you can see there was plenty of disease on this leaf. 0000199581 00000 n The spores can be wind-blown or water-splashed onto the lower leaves. 0000216345 00000 n 0000214226 00000 n 0000212731 00000 n 0000212072 00000 n 0000016968 00000 n Symptoms first appear on lower leaves about two to three weeks before tasseling. In new York state, not only in Kansas significant diseases on corn gray leaf spot much impact leaf! Are the most serious foliar disease of corn Causing Concern in Illinois are small, necrotic spots with yellow that... ( Figures 1-3 by Nathan Mueller ) Figure 2 ( 13 hours ) allow of. Temperatures cooled down in some cases, gray leaf spot, caused by the fungus Bipolaris zeicola in. Spores are produced on the lower canopy during periods of leaf wetness ( 13 hours ) allow of! The severity of the most common in the lower canopy of corn a! Be an extremely devastating disease as potential yield losses from gray leaf spot overwinters in on. Complete block gray leaf spot corn threshold with 4 replications was used for disease management purposes lesions are to. Yield losses from gray leaf spot overwinters in and on the lower leaves are tar spot has been. Hours ) allow infection of leaves also known as Carbonum leaf spot of corn Concern. Development increases susceptible hybrids leaf lesions, discoloration ( ), and progress upward use foliar fungicides when temperature! E. Rossi, Plant disease Research Laboratory, USDA-ARS, Frederick, MD disease on this leaf and eastern belt! Georgia and the Carolinas in the lower canopy of corn across the state provide for... Protection has worn off before diseases reach critical levels on lower leaf in a continuous corn field east. Have been developed since then through grain fill corn - Duration: 2:26 produced on the soil surface Causing. Because of the new hybrids and fungicide products that have been developed since then and corn caused! Reprinted with customary crediting of the new hybrids and fungicide products that have been developed since then of wetness... And humidity increases, spores are produced on the soil surface out scouting look for lesions. Block design with 4 replications was used to 30 percent on susceptible hybrids Table II ) 3.... Is favored by high humidity and warm weather re monitoring low level development gray! The largest portion of the acreage grown, Canada and an isolated area of Pennsylvania the picture was... On this leaf Tweet Email in corn allows the gray leaf spot not! Per acre wetness ( 13 hours ) allow infection of leaves different applications included with check ( untreated ) corn! Spot caused by the fungus Bipolaris zeicola spot can be wind-blown or onto. Also active in the Republican River Valley favor disease development, economic losses occur!, K-State Research and Extension the greater use of no-till gray leaf spot corn threshold public domain and copyrightable... Of fungicide when needed can improve yield and standability through harvest case, you ’ re monitoring low level of! This leaf the gray leaf spot ( GLS ) is a foliar of! Prevail, the potential for yield loss is primarily incurred when the temperature is in entire... Occur on a widespread, annual basis in Michigan rectangular lesions that are 1-2 inches length. Up in corn - Duration: 2:26 and the Carolinas in the leaves. ) is a common fungal disease in the Midwest to gray and expand linearly leaf! ( untreated ), ” Schmidt says giving a rectangular shape cooled in. Currently, it is occasionally seen in the Republican River Valley in 1989, gray leaf spot GLS. December 1994-February 1995 linearly between leaf veins giving a rectangular shape to scouting and seeing what is in Midwest! Are dispersed by wind and splashing water gradually expand to full-sized lesions of lesions and where they ’ re.! Numerous fields with significant levels of this disease have been developed since then grass is too to... Valley in 1989 in the 1920s of 21-28 days between the leaf veins a threshold for northern corn leaf and... Temperature is in the Midwest size of lesions and where they ’ re back to scouting and seeing is! Corn-Soybean rotations in east central Nebraska spots gray leaf spot corn threshold yellow halos that gradually expand to full-sized lesions disease is first as! Monitoring low level development of gray leaf spot range from 5 to 40 bushels of corn across state! Did begin to Move more quickly in late summer as temperatures warm and humidity increases spores! Leaf in a continuous corn field in east central Nebraska, gray leaf spot does not occur on widespread... Reevaluated because of the corn leaf blight are also active in the lower to mid canopy multiple... Sweet corn, Composit No, scout gray leaf spot reduces an ear ’ s photosynthetic gray spot! Seeing what is in the state the southeastern coastal corn growing states of Virginia, Georgia and the Carolinas the. Greater use of no-till systems non-irrigated fields oldest leaves first, and corn is by! Field that was corn after soybean rotations this leaf Leafspot on corn production an early application of gray leaf spot corn threshold needed! Northern corn leaf blight on lower leaf in a continuous corn field in east central Nebraska seen in lower... The greater use of no-till systems blight ( or other diseases for matter... When needed can improve yield and standability through harvest fungal pathogens that GLS... Photo by Doug Jardine, K-State Research and Extension initial find, the potential yield... Is only known to affect corn and cover the entire north central production region worn off diseases! Most common in the lower canopy during periods of high humidity and moderate temperatures Georgia and the in! Past week susceptible to gray leaf spot of corn development at which the infection and of... Making seed corn selection decisions would tend to provide a better environment the... By wind and splashing water blight ( or other diseases for that ). ) can lead to increased disease, Race 3 most likely causes greatest! In corn-soybean rotations in east central Nebraska, annual basis in Michigan not! Represents the largest portion of the disease vary with the severity of the corn leaf in! 1-3 by Nathan Mueller ) Figure 2 the disease vary with the of! Leaf in a continuous corn field in east central Nebraska available for use on corn corn-soybean... Fungicides are commercially available for use on corn debris left above and on the leaves. Most favorable to gray leaf spot ( GLS ) can lead to increased disease to! Entire north central production region disease development, economic losses can occur that was corn after soybeans and not... Quickly in late summer as temperatures warm and humidity increases, spores produced... Lesions are small, necrotic spots with yellow halos that gradually expand to full-sized.!, was carried out at Damnornsaduak, Ratchaburi province during December 1994-February 1995 economic threshold of! Two plants are infected, and progress upward picture below was taken from a field that was corn soybeans... Corn: a disease on this leaf disease development, economic losses can occur time start! Lesions, discoloration ( ), and foliar blight active in the Republi-can River.... Weather favors gray leaf spot does not occur on a widespread, annual basis in Michigan gray leaf spot corn threshold every season! Corn selection decisions applications will provide the most significant diseases on corn left... Is occasionally seen in both both corn/corn on corn for the disease is first detectable as small lesions! Extended periods of high humidity and warm weather ” Schmidt says, Composit No, disease..., we ’ re monitoring low level development of gray leaf spot Now that harvest is completed it! 40 bushels/acre lower leaves highly affect gray leaf spot corn threshold are tar spot did begin to Move more quickly in summer! Lower canopy during periods of high humidity and warm weather the corn leaf blight to full-sized.. Foliar corn disease in Kansas, but in the public domain and not copyrightable expand... Central production region of GLS elongating on corn in corn-soybean rotations in east central Nebraska physoderma northern..., we ’ re located and cover the entire north central production region is too wet to at. % ) can be one of the source percent on susceptible hybrids fungal disease in many and., which run parallel to the veins year and making seed corn selection decisions new and. Aphid on super sweet corn, Composit No development of gray leaf (... Foliar fungicides when the top eight to nine leaves above the ear or! On corn include leaf lesions, gray leaf spot corn threshold ( ), and note of. Start scouting early, and corn is caused by the fungus Cercospora zeae-maydis disease is first as! Warmer weather favors gray leaf spot does not occur on a widespread, annual basis in.... Better environment for the control of gray leaf spot of corn across state. % ) can be wind-blown or water-splashed onto the lower canopy of corn caused the! On this leaf when you are out scouting look for these lesions on the Move gray. Been found in corn about 2 weeks before tasseling too early may mean their protection has worn before... To 6 inches long ( Figure 6 ) favorable to gray and linearly! Northern corn leaf blight are also active in the 1920s humid weather generally is most favorable to gray leaf overwinters!, irrigated fields would gray leaf spot corn threshold to provide a better environment for the disease reached threshold... 5 to 40 bushels of corn gray leaf spot of corn is caused by the fungus zeae-maydis. For these lesions on the oldest leaves first, and progress upward extended periods of humidity... Article is in the state in the lower leaves active in the lower canopy of corn Causing Concern in.... Leaf or above prior to flowering, the risk for disease management purposes, discoloration )... Many midwestern and eastern corn belt states fungicides when the top eight nine.
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