Friday, June 14, 2013
soybean-herbiciide-injury-06162013-feature

Herbicide Symptoms of Injury After Excess Rains

AgFax.Com - Your Online Ag News Source


Excessive rains timed with very recent planting and pre-herbicide applications or from late-applied post treatments delayed (by rains) are always a concern in some fields. Growers and advisors are wise to familiarize themselves with the symptoms.

Most cases of herbicide injury in field crops can be traced to six herbicide classes or families: triazines, ALS-inhibitors, HPPD-inhibitors, plant growth regulators, PPO-inhibitors, and glyphosate. Below are some common symptoms associated with each of the herbicide groups.

  • Triazines (Group 5): Triazines are photosynthesis-inhibiting herbicides that block the photosynthetic process, so captured light cannot be used to produce sugars. The plant slowly starves to death due to lack of energy. In broadleaved plants, early seedling growth appears normal, but shortly after emergence (when energy reserves in cotyledons are depleted), leaves become mottled, turn yellow to brown, and die. In most cases, the oldest leaves turn yellow on the leaf margins first, the veins remain green, and eventually the plant turns brown and dies. Herbicides such as atrazine, simazine, metribuzin, and Velpar could cause this kind of injury.
  • ALS-inhibitors (Group 2): These herbicides work by interfering with one or more key enzymes that catalyze the production of specific amino acids in the plant. When a key amino acid is not produced, the plant’s metabolic processes begin to shut down eventually causing plant death. Plants that are sensitive to these herbicides stop growth almost immediately after foliar treatment; seedlings die in three to seven days, established perennials in two to four weeks. Symptoms include: stunted, yellow, purple veins, dead growing point, roots malformed (bottle-brush).These herbicides have systemic activity throughout the plant and young leaves are affected first. Grass plants may be stunted, with interveinal yellowing (chlorosis) or purpling. Corn plants may be stunted and show symptoms of root inhibition such as pruning of lateral roots. Leaves emerging from the corn whorl may not unfurl properly and may be yellow to translucent in appearance. Broadleaf plants may be stunted and chlorotic or purple. Soybean injury can range from stunting to death of the terminal growing point. Soybean leaves may be yellow in appearance and leaf veination may appear red or purple in color. Herbicides such as Classic, Resolve, Cimarron, Permit, Pursuit, Scepter, and Python can cause this kind of injury.
  • HPPD-inhibitors (Group 27): These products are referred to as “bleachers” since they interfere with normal chlorophyll formation. Symptoms are very evident and easy to identify. Effected plants turn white or show bleached leaves, and eventually die if concentration of herbicide is high enough. Herbicides that contain HPPD active ingredients include: Lumax, Lexar, Balance, Corvus, Callisto, Impact, and Laudis. Clomazone (Command, component of Strategy) is not an HPPD-herbicide but is also considered a bleaching herbicide since the symptoms are similar.
  • Plant growth regulators (Group 4): In most cases PGR damage occurs not from carryover but from herbicides that are sprayed in adjacent fields and then drifts onto the susceptible crop. PGRs upset normal growth as follows: cells of leaf veins rapidly divide and elongate, while cells between veins cease to divide. This results in long, narrow, strap-like young leaves. Water content increases, making treated plants brittle and easily broken. Cell division and respiration rates increase, and photosynthesis decreases.Food supply of treated plants is nearly exhausted at their death. Roots of treated plants lose their ability to take up soil nutrients, and stem tissues fail to move food effectively through the plant. The killing action of growth-regulating chemicals is not caused by any single factor, but results from the effects of multiple disturbances in the treated plant. Symptoms include: broadleaf plant leaves become cupped, crinkled, puckered, strap-shaped, stunted, and malformed; leaf veins appear parallel rather than netted, and stems become bent, twisted, and brittle, with shortened internodes. Typical herbicides in the PGR family that could cause problems if they drift to adjacent vegetable crops are 2,4-D and dicamba (Banvel, Clarity.
  • PPO-inhibitors (Group 14): These herbicides are referred to as contact herbicides and they kill weeds by destroying cell membranes. They appear to burn plant tissues within hours or days of application. Good coverage of the plant tissue and bright sunlight are necessary for maximum activity. The activity of these herbicides is delayed in the absence of light. Injury symptoms: all contact herbicides cause cellular breakdown by destroying cell membranes, allowing cell sap to leak out.Effected plants initially have a “watersoaked” appearance, followed by rapid wilting and “burning,” or leaf speckling and browning. Plant death occurs within a few days. However, some of the PPO-inhibitors have longer soil residual activity so potential carryover is a concern. Products like Reflex, Flexstar, Authority, Spartan, and Valor can cause injury to certain crops if recropping restrictions are not followed.
  • Glyphosate (Group 9): Plant foliage, especially new growth, will first yellow and then turn brown and die within a week or so after herbicide application. Sometimes new leaves on sensitive plants exhibit a bright yellow or even white appearance which can be confused with injury from other herbicide groups.

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: Wheat Basis Climbs but Fundamental Still Bearish3-3

    DTN Livestock Close: Profit Taking Pressure3-3

    Soybeans: How Low Can Planting Rates Safely Go? – DTN3-3

    Doane Cotton Close: Lower Global Demand Expectations3-3

    Japan Reduces Hurdles to Pacific Trade Deal Progress – DTN3-3

    New Videos Shows Weeds Time-Lapsed Reaction to Herbicides3-3

    DTN Fertilizer Trends: Northern Farmers Glad for Lack of Delays3-3

    DTN Cotton Close: India Sales Insignificant3-3

    Pennsylvania: 4 Weed Resistance Workshops, March 17-203-3

    North Carolina: Farming on Leased Land Workshop, Mills River, April 93-3

    DTN Grain Closing: More Roads Open in Brazil3-3

    USDA: Weekly National Peanut Prices3-3

    DTN Livestock Midday: Cattle Complex Pressured by Liquidation3-3

    DTN Grain Midday: Brazil Trucker Strike Losing Momentum3-3

    Cotton: Topguard Gets Full Registration, Pay Attention to Use Rates3-3

    Crop Insurance: Soybean Projected Prices Down 10¢ from 20143-3

    Immigration Reform: House E-verify Not Enough, Says Ag Coalition3-3

    DTN Cotton Open: Coils Quietly Near Lows3-3

    DTN Livestock Open: Prices Poorly Defined; Trade Volume Delayed3-3

    Keith Good: U.S. Hog Price Calamity; Right to Ban GMO, Says European Union3-3

    Fertilizer Management: Watch Out for Burns from In-Furrow Starters – DTN3-2

    Keith Good: Ethanol Profits; California Rains – Just Drop in the Drought Bucket3-2

    Herbicide-Resistance: 12 Steps to Keep Weeds Away3-2

    AFB Grain-Soybean Close: Negative News Day3-2

    AFB Cotton Close: Slightly Mixed3-2

    AFB Rice Close: Market Mostly Higher3-2

    Hogs: Price Collapse – ‘Buy the Rumor, and Sell the Fact.’ – Podcast3-2

    DTN Fertilizer Outlook: Harsh Winter to Keep Prices Flat3-2

    Corn Planting: New Technology Worth the Money – DTN3-2

    DTN Grain Close: Brazil Strike Wears Down3-2

    Grain Sorghum: Great Rotation Crop – Acres Growing in Mid-Atlantic Region3-2

    Arkansas: Tyson Gives $5M to Help Fund Center for Ag Sciences3-2

    Keith Good: Crop Insurance Guarantees to Fall; California Drought “Catastrophic”;3-2

    Rose on Cotton: Gin Show Visit – High Quality Cotton Still in Demand2-28

    Trade Promotion Authority: Vilsack Whips Up Support2-27

    Ethanol: Corn Growers Defend RFS – DTN2-27

    Planting: New Rigs at the Top of Their Game – DTN2-27

    Rice Market: Only Feeble Signs of Price Improvement2-27

    Wheat: Study Sheds Light on Stem Rust Disease in Africa and Asia2-27

    Nebraska: Can You Shoot an Uninvited Drone?2-27

    Turkey Hunting: Tips for the Spring Gobbler Season2-27

    Cotton Base Acres Count as Generic Base Under Farm Bill2-27

    Soybeans: Monsanto Plans In-Field Training for Roundup Ready2 Xtend2-27

    DTN Cotton Close: Texas Could See More Freezing Rain, Snow2-27

    Shurley on Cotton: Improvement Slows Down, but What Else Did We Expect?2-27

    Peanut Stocks and Processing: Utilization Up 7%2-27

    USDA: Peanut Price Highlights2-27

    Weekly Cotton Market Review – USDA2-27

    Keith Good: Chinese Corn Imports Not Likely to Recover; Food Stamp Debate Rages On2-27

    Georgia Celebrates National Peanut Month with PB&J Day, Donations2-27

    USDA Changes Deadline: Yield History Update, Reallocation Base Now Due March 312-27

    U.S. Grain Transportation: West Coast Ports Return to Normal2-27

    Pinnacle’s Sanders in 9 Southern States with Newest Acquisition2-27

    South Carolina: Got Wild Hogs? Time To Speak Up.2-27

    Texas: Master Marketer Program Hits 25th Year, Going Strong2-27

    Louisiana Rice: Losing Methyl Bromide Creates Challenge For Bin Insect Control2-27

    Iowa Senate Approved Tougher Restrictions on Manure Applications – DTN2-26

    NFL Star Turned Farmer Engages Youth, Community Through Ag – DTN2-26

    Chumrau on Wheat: USDA Forecasts Higher Production in 2015-162-26

    Corn Yields: Expectations for the 2015 Average – What Does History Teach Us?2-26

    ELS Cotton Competitive Payment Rate Is Zero2-26

    NRCS Invests $84M Natural Disaster Funds in 13 States2-26

    Georgia: Crabgrass Control Depends on Soil Temperatures2-26

    DTN Cotton Close: Bounces Off New High2-26

    Early Spring Best Time to Test and Tune Farm Machinery2-26

    Ag Conservation Easement Program Accepting Comments on Final Rule2-26

    Pesticide Drift: Calm, Still Days Are Most Dangerous – DTN2-26

    Livestock: Port Resumptions Bring Meat Industry a Sigh of Relief – DTN2-26

    Keith Good: Global Soybean Issues; Vilsack on Crop Insurance; Food Stamps Re-Revisited2-26

    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 +