Thursday, July 03, 2014
downy_mildew_lesions_on_soybean_t_r_faske

Arkansas Corn, Soybeans: Common Foliar Diseases That Don’t Need Fungicides

AgFax.Com - Your Online Ag News Source


Throughout the growing season there are several foliar diseases that affect soybean and corn production in Arkansas. These include a few minor diseases that do not warrant a fungicide because they do not cause any significant yield loss. Currently, a few of these minor soybean and corn diseases are present in fields across the state.

It is common to find downy mildew in practically every soybean field in the mid-South. Typically, it is first observed in the lower canopy then later in the growing season on leaves in upper canopy. Early symptoms are pale green or light yellow lesions on the upper leaf surface. Fuzzy tufts of spores can be observed on the lower leaf surface. Lesions are lighter than frogeye leaf spot, an important disease that also produces fuzzy tufts of spores.

 
 


Currently, frogeye leaf spot is picking up in many soybean fields across the state. Though downy mildew can appear severe in some cases, commercially available fungicides have little activity on downy mildew; thus, fungicides are not economically beneficial to control this disease.

Ascochyta leaf spot is often found in the lower canopy throughout the growing season. It looks similar to frogeye; however, black fungal fruiting structures (“black dots”) can be seen on the upper leaf surface. This disease often develops in old frogeye leaf spot lesions or spots caused by herbicide injury.

Bacterial leaf blight is often limited to the lower soybean canopy. Angular lesions differentiate this disease from brown spot, another minor disease of soybean that occurs later in the season. Close inspection of the lesions often reveals a “bacterial exudate” on the underside of the leaf. This pathogen can move up the canopy when conditions favor disease later in the growing season, but typically does not move up the canopy during dry growing conditions. A fungicide will not control a bacterial disease thus, fungicides provide no protection for this disease.

Of the few corn diseases that have been observed this year, common rust has been the most frequent. Typically common rust occurs low in the corn canopy; however, this year in rare instances it has been observed in the mid- to upper-canopy. Common rust is a minor pathogen on corn and no fungicides are recommended for control of this disease. Pustule development on the lower leaf surface differentiates common rust from southern rust, which has yet to be reported this year in Arkansas.


Tags: , , , , , , , , , ,


Leave a Reply

Name and Email Address are required fields. Your email will not be published or shared with third parties.

Sunbelt Ag News

    Grain TV: Markets Hit by Selling Pressure10-30

    DTN Livestock Close: Cattle Complex Enjoys Short-Covering Rally10-30

    Doane Cotton Close: Strong Exports Continue10-30

    ELS Cotton Competitive Payment Rate Is Zero10-30

    AFB Grain-Soybean Close: Strong Exports Unable to Support Prices10-30

    AFB Cotton Close: Futures Retrace Gains10-30

    AFB Rice Close: Futures Turn Strongly Lower10-30

    Biodiesel: 2014 A Tough Year for Producers10-30

    DTN Cotton Close: Reverses off New High to End Lower10-30

    Kansas Officials Point Out Flaws in Clean Water Act – DTN10-30

    DTN Grain Close: Rally Pauses as Prices Backtrack10-30

    Ag Secretary Discusses Challenges Facing Future Farmers — DTN10-30

    DTN Livestock Midday: Sharp Losses Develop in Hog Futures10-30

    U.S. Grain Transportation: Barge Rates Remain Well Above Average10-30

    Mississippi: Fall Tests for Nematodes Help Keep Crops Healthy10-30

    DTN Grain Midday: Trade is Flat to Lower10-30

    DTN Cotton Open: Futures Tick Near Unchanged10-30

    California’s SJV Included in Report on Soil Loss to Salt Damage10-30

    U.S. Energy: Gas Prices Drop to Lowest Since December 201010-30

    Gasoline Prices: Average Drops 6 Cents10-30

    Propane Stocks: Down 1.3M Barrels10-30

    Diesel Prices: Decrease by 2 Cents10-30

    New Research Study Shows the Value of Neonics10-30

    DTN Livestock Open: Futures Staged for Mixed Start10-30

    DTN Grain Open: Markets Extend Rally Overnight10-30

    Keith Good: Drought Impacts California Rice; Farm Land Market Cools10-30

    Texas: Pecos County Pesticide Workshop, Fort Stockton, Nov. 1810-29

    Florida: Sugarcane Field Day, Quincy, Nov. 310-29

    Texas Wildlife: New Deer Management App Just in Time for Deer Season10-29

    Peanut Stocks: Utilization Up 6%, Stocks Total 1.2B Pounds10-29

    Georgia: Brooks County Clean Day Rescheduled to Nov. 1210-29

    AgFax Cotton Review: U.S.’s High Quality Offers Market Resilience10-29

    Georgia: USDA Designates Early County Primary Natural Disaster Area10-29

    China Consumers Often Misled on GMO Food Issues — DTN10-29

    DTN Fertilizer Outlook: Demand May Fall with Crop Prices10-29

    Grain Market Math Test, Part 2 — DTN10-29

    Welch on Wheat: Crop Condition Right on Average10-28

    Welch on Grain: Corn Harvest Runs Behind but Conditions Remain High10-28

    USDA: Weekly National Peanut Prices10-28

    Mississippi Wild Hogs: Trapping Is the Best Control Method10-28

    DTN Fertilizer Trends: Stubborn Prices Pose Dilemma for Grain Farmers10-28

    What Happens to Corn Prices When Stock Market Falls? — DTN10-28

    Georgia Peanuts: Spider Mite Damage Rises in Dry Weather10-28

    Vilsack: COOL Appeal Decision to be Made in January — DTN10-27

    Livestock: Record Cattle Prices, Again and Again10-27

    AgFax Rice Review: Defense Against Arsenic; Japan’s Modernization10-27

    Mandatory COOL: Detrimental to Trade, No Easy Solution — Economist10-27

    Group Works to Improve Fertilizer Efficiency — DTN10-27

    Shurley on Cotton: Lackluster Week Closes on High Note10-27

    China’s U.S. Corn Rejections Prompt New Business — DTN10-27

    Flint on Crops: Mississippi Snow Arrives in October10-27

    Sunbelt Ag Events

     

    About Us

    AgFax.Com covers agricultural trends and production topics, with an emphasis on news about cotton, rice, peanuts, corn, soybeans, wheat and tree crops, including almonds, pecans, walnuts and pistachios.

      

    This site also serves as the on-line presence of electronic crop and pest reports published by AgFax Media LLC (formerly Looking South Communications).

        

    Click here to subscribe to our free reports.

      

    We provide early warnings and confirmations about pests, diseases and other factors that influence yield. Our goal is to quickly provide farmers and crop advisors with information needed to make better and more profitable decisions.

         

    Our free weekly crop and pest advisories include:

    • AgFax Midsouth Cotton, covering cotton production and news in Alabama, Arkansas, Louisiana, Mississippi, Tennessee and Missouri.

    • AgFax Southeast Cotton, covering cotton production and news in Alabama, Florida, Georgia, North Carolina, South Carolina and Virginia.

    • AgFax Southwest Cotton (new for 2013!), covering cotton production and news in Texas, Oklahoma, Kansas and New Mexico.

    • AgFax West (formerly MiteFax: SJV Cotton), covering California cotton, alfalfa, tomatoes and other non-permanent crops in California's Central Valley.

    • AgFax Rice covering rice production and news in Arkansas, Louisiana, Mississippi, Missouri and Texas.

    • AgFax Peanuts, covering peanut production in Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Texas and Virginia.

    • AgFax Southern Grain: covering soybeans, corn, milo and small grains in Southern states.

    • AgFax Almonds, covering almonds, pistachios, walnuts and other tree crops in California's Central Valley.

    • AgCom 101, providing guidance to ag professionals involved in social media.

    Our newsletters are sponsored by the following companies: FMC Corporation Chemtura Dow AgroSciences.

          

    Mission statement:

    Make it as easy as possible for our community of readers to find and/or receive needed information.

              

    Contact Information:

    AgFax Media. LLC

    142 Westlake Drive Brandon, MS 39047

    601-992-9488 Office 601-992-3503 Fax

    Owen Taylor Debra L. Ferguson Laurie Courtney

          

    Circulation Questions?

    Contact Laurie Courtney