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

    DTN Livestock Close: Lean Hog Futures Collapse Further7-29

    Doane Cotton Close: Sharp Losses on Improved Conditions7-29

    Keeping Farm Management in Line with Increasing Regulations – DTN7-29

    DTN Cotton Close: Ends on New Contract Low7-29

    Mississippi: MSU Wild Hog Research Needs Foresters, Farmers7-29

    DTN Grain Close: Markets Slide Lower7-29

    USDA: Weekly National Peanut Prices7-29

    AgFax Grain Review: Chinese Trade Issues Continue; Navy to Purchase 37M Gallons of Biofuels7-29

    DTN Livestock Midday: Lean Hog Futures Retreat Farther7-29

    DTN Grain Midday: All 3 Commodities Lower7-29

    DTN Cotton Open: Trades Lower in Early Going7-29

    DTN Livestock Open: Lean Hog Futures on Defensive7-29

    DTN Grain Open: Futures Falter, Start Lower7-29

    Keith Good: Bugs’ Resistance to GMO Corn in Brazil Proving Costly7-29

    AFB Grain-Soybean Close: Wheat Unable to Follow Corn, Soybeans Higher7-28

    AFB Cotton Close: Moves Higher in Narrow Range7-28

    AFB Rice Close: Futures Down Slightly7-28

    Crop Progress: Corn, Soybean Conditions Decline, Still at Historical Highs – DTN7-28

    DDGs: China Issues New Import Rules, U.S. Unlikely to Comply – DTN7-28

    Cattle: Minimizing the Risk of Scours — DTN7-28

    Good on Grain: Storing the 2014 Corn Crop7-28

    DTN Fertilizer Outlook: Domestic Ammonia Prices Down Slightly7-28

    Flint on Crops: Challenges for Farmers Keep Coming, Keep Changing7-28

    USDA Commentary: Weekly Cotton Markets, Weather by Region7-25

    Rose on Cotton: No Pleasure in this Market Made for Bears7-25

    Rice Market: U.S. Futures Decline as Global Prices Rise7-25

    Rice Crop: Harvest Begins Slowly in Louisiana and Texas7-25

    Rice Commentary – Rice Farmers Need to Consider a New Business Plan7-25

    Leave Your Guns at the House, Boys.7-25

    Peanuts: 15% Of Crop Ungathered In Key Argentine Production Area7-25

    Rail Car Delays Causing Dread Among Elevator Operators – DTN7-25

    Catfish Production: Water Surface Acres at 63,700 Acres7-25

    USDA: Peanut Price Highlights7-25

    Arkansas: New iPhone App Simplifies Farmers’ Finances7-25

    Taking the Risk Out of Buying Used Equipment — DTN7-25

    North Carolina: Rediscovering Grain Sorghum — DTN7-25

    Peanuts: Worms Still Building In SE; Rains Boost West’s Crop – AgFax7-25

    Shurley on Cotton: Prices Try to Stabilize, Still Show Weakness7-25

    Southern Soybean Insect Situation Gets Complicated – AgFax7-25

    AgFax Wildlife Review: Wild Hogs Damaging Levees in Louisiana7-25

    Ethanol: Final 2014 RFS Release ‘Imminent’ – DTN7-24

    Doane Cotton Close: Prices Break Out of Range Lower7-24

    New Rural Infrastructure Fund Established — DTN7-24

    U.S. Grain Transportation: Wheat Demand Increases, Inspections Rise7-24

    2014 Farm Bill Decisions: Base Acre Reallocation Option7-24

    Louisiana: Sodium Nitrite Explored for Wild Hog Control7-24

    U.S. Energy: Refineries Running at Record Levels7-24

    Gasoline Prices: Show 4-Cent Decrease7-24

    Propane Stocks: Continue to Rise7-24

    Diesel Prices: Average Declines by 3 Cents7-24

    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