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

    Happy Thanksgiving from AgFax Media!11-27

    AFB Grain-Soybean Close: Corn, Wheat Higher, Soybeans See Modest Losses11-26

    AFB Cotton Close: Prices Surge Higher11-26

    AFB Rice Close: Jan, March Chart Bullish Key Reversals11-26

    Energy: N. American Oil Companies See Improved Financial Results in 3rd Quarter11-26

    Residential Heating Oil Prices Lower11-26

    Propane Stocks Fall 2M Barrels11-26

    Gasoline Prices Drop 7 Cents11-26

    Diesel Prices Fall 3 Cents11-26

    Texas: Hopkins County Designated Natural Disaster Area11-26

    Kansas: 4 Counties Declared Natural Disaster Areas11-26

    Alabama: 4 Counties Designated as Primary Disaster Areas11-26

    Texas Pecans: Demand Good but Quality Variable11-26

    Louisiana Pecans: Light Deliveries, Good Buying Interest11-26

    Georgia Pecans: Prices Slightly Higher with Strong Trade11-26

    DTN Livestock Midday: Pressure Develops in Cattle Trade11-26

    DTN Grain Midday: Soybeans Slip 5 to 10 Lower11-26

    Farmers Share What They’re Thankful For — DTN11-26

    GMO Crops Have Facts on Their Side, but Debate Goes on — DTN11-26

    DTN Cotton Open: Posts Slight Gains in Quiet Trade11-26

    Wheat: Make One Last Scouting Trip This Fall — DTN11-26

    Farm Income Down 21%; Expenses Up 5.7% – USDA Forecast11-26

    DTN Livestock Open: Futures to Start on Mixed Basis11-26

    DTN Grain Open: Wheat Leads Markets Higher11-26

    Keith Good: Net Farm Income to Drop 21.1% from 2013, ERS Forecasts11-26

    DTN Livestock Close: Feeder Futures Knocked Hard for 2nd Session11-25

    Livestock: 6 Tips to Fight PEDv This Fall11-25

    Doane Cotton Close: Outside Strength Helps Prices Rebound11-25

    AgFax Cotton Review: New Stink Bug App; India Exports Drop11-25

    DTN Cotton Close: Higher on Light Volume11-25

    Tax Breaks: Waiting for 2014 Equipment Deduction, Biofuel – DTN11-25

    DTN Grain Close: Bean Complex Rallies, Grains Follow11-25

    USDA: Weekly National Peanut Prices11-25

    Georgia: 10 Farm Bill Meetings Scheduled for Mid Dec.11-25

    AgFax Rice Review: Iraq Resumes U.S. Purchases; Cambodia Wins Best Rice Award11-25

    Winter Weather Creates More Problems for Railroads — DTN11-25

    Future of Cellulosic Biofuels in U.S. Questioned — DTN11-25

    AgFax Peanut Review: Growers Urged to Plant Earlier; Texoma Sells Drying Facility11-25

    Shurley on Cotton: New Round of Weakness Sets In11-25

    Welch on Wheat: Crop Condition Down Slightly11-24

    Welch on Grain: Snow Keeps 770M Bushels of Corn in Field11-24

    Farmland Partners Buys 7 South Carolina Farms for $28M11-24

    Livestock: Hog and Pork Prices Return to Reality11-24

    Corn: Breaking Down Stalks Takes Thought, Planning — DTN11-24

    DTN Fertilizer Outlook: Winter’s Arrival May Delay Some Buying11-24

    Brazil Soybeans: Dry Conditions Still Cause for Concern11-24

    Flint on Crops: Low Input Farming May be Necessary in 201511-24

    Midwest Corn And Soybean Yields – Our Readers’ Reports – AgFax11-22

    Rice Comment: The Case for Neonicotinoid Seed Treatment11-22

    U.S. Rice: Rain Stalls Texas 2nd Crop Harvest; Crop Sales Continue11-22

    Rice Market: Sale to Iraq Moves the Market11-22

    Rose on Cotton: Looking for the Positives This Week11-21

    Grain Drying: 6 Questions About Effects Of Sudden Drop In Temps11-21

    Is Your Lifestyle Costing You the Farm?11-21

    Farmers Storing Grain Need to Weigh Risk Management Factors – DTN11-21

    Peanut Harvest Updates From Southeast, Delta And Southwest – AgFax11-21

    Cleveland on Cotton: 57 Cents – ‘The Bottom is In’11-21

    Ag Labor: Immigration Order Provides Little Long-Term Benefit – DTN11-21

    USDA: Peanut Price Highlights11-21

    Ag Policy: Farm Bills Need Long-Term View11-21

    Cotton Market Weekly Review by Region11-21

    Arkansas Cattle: Ranchers Should be Alert to Acorn Poisoning11-21

    Economist: Livestock Industry Will Have Strong Rebound11-21

    DTN Dried Distillers Grain: Cheaper Feed Source for Beef Producers?11-21

    Mississippi Outdoors: Common Deer Parasites Do Not Affect Venison11-21

    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