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

    Rose On Cotton: Export Sales, Shipments Bear Watching4-18

    Arctic Warming Tied to Our Extreme Weather? Maybe. – DTN4-18

    Do Soybeans Need Fertilizer?4-18

    Is There An Advantage To More Corn Acres in Your Rotation? Yes and No.4-18

    Texas Rice: Garry McCauley Retires After 39 Years and Many Accomplishments4-18

    CBOT Markets Closed on Good Friday4-18

    Keith Good: China’s Secret – Contaminated Farmland; Expect Drought Persistence4-18

    Rice Farmers In Midsouth Looking For A Break In The Weather – AgFax4-18

    Cleveland on Cotton: Nervous Market Nellies; Chinese Plant 20-25% Less4-17

    Grain TV: River Basis Levels See Large Rise4-17

    AgFax Grain Review: Corn Production Moves to Canada; Soybean Cyst Nematodes Unaffected by Cold4-17

    DTN Livestock Close: Meat Futures Take Wide Swings Before Exiting for Holiday4-17

    Doane Cotton Close: Heavy Volatility Continues in Old-Crop Prices4-17

    Chumrau on Wheat: World Supplies Get a Lift, but U.S. Stocks Look Tight4-17

    AFB Grain-Soybean Close: Wheat Higher, Corn Down, Beans Mixed4-17

    AFB Cotton Close: New-Crop Continues to Show Strength4-17

    AFB Rice Close: Across the Board Losses4-17

    DTN Cotton Close: Finishes Mixed Ahead of Long Weekend4-17

    Mississippi: MSU Offers Four Deer Management Workshops This Summer4-17

    Mapping the Farm Bill: Voting Changes in the House of Representatives4-17

    DTN Grain Close: Markets Mixed Ahead of Holiday Weekend4-17

    USDA: Peanut Price Highlights4-17

    Texas: Grain Grading Workshops, Amarillo, May 6-74-17

    Mississippi: State Soybean Value Grew $1B Since 20064-17

    U.S. Drought Outlook: Improvement Expected in Midwest, Central and Southern Great Plains4-17

    Farm Finances Rate an ‘A’ For Now, but Questions Linger — DTN4-17

    DTN Livestock Midday: Sharp Losses Hold in Cattle Trade4-17

    Mississippi: Top of the List for Water Resouces4-17

    DTN Grain Midday: Corn, Soybeans Move Lower4-17

    U.S. Grain Transportation: Upper Mississippi Navigation Improves4-17

    Resistant Palmer Pigweed: What People Need To Know Before It Hits – AgFax4-17

    Chemical Safety Board Plans Meeting in West, Texas — DTN4-17

    West, Texas, Recovers and Rebuilds with Cautious Approach — DTN4-17

    DTN Cotton Open: Trades Slightly Lower Nearby4-17

    U.S. Energy: Oil and Gas Spending Favors Exploration, Development4-17

    Gasoline Prices: Average Jumps 6 Cents4-17

    Propane Stocks: Increase by 0.8M Barrels4-17

    Diesel Prices: Average Down a Penny4-17

    DTN Livestock Open: Meat Contracts to Start Lower4-17

    Victims of Texas Fertilizer Plant Explosion Remembered — DTN4-17

    DTN Grain Open: Higher Start Led by Soybeans4-17

    Keith Good: Beige Book — Observations on Ag Economy4-17

    “Agricultural Adventure” Educate Public on Modern Farming – DTN4-16

    International Buying and Selling a Balancing Act to Get the Best Deal – DTN4-16

    AgFax Rice Review: Recent Rains Won’t Help CA Farmers; Japanese Varieties Grown in U.S.4-16

    Weather Woes Stretch from Iowa to Florida — DTN4-16

    Brazil’s Ports Remain Orderly with Good Luck, Favorable Conditions – DTN4-15

    Texas: Conservation Farming Meeting Weslaco, April 294-15

    Welch on Wheat: Cool Temperatures Hit Drought Stressed Crop4-15

    N.C. State University Leads Research into Kudzu Bug Host Preferences4-15

    Welch on Grain: Corn Planting in Line with 30 Year Average4-15

    Fertilizer Prices on the Rise but Still Lower Than Last Few Years4-15

    USDA: Weekly National Peanut Prices4-15

    Louisiana: Wildlife Field Day, Clinton, May 34-15

    Sign Ups Begin for USDA Disaster Assistance Programs4-15

    AgFax Cotton Review: Now’s a Good Time to Price New-Crop; Rains in Texas but Not Enough4-15

    DTN Fertilizer Trends: Rail Delays Affecting Prices in Upper Midwest4-15

    Crop Progress: 3% of National Corn Crop Planted, Wheat Continues Decline – US-DA4-14

    Louisiana: Glyphosate Resistance Confirmed in Italian Ryegrass4-14

    Livestock: Rancher Raises Horns, Not Pounds for Rodeo Cattle – DTN4-14

    Good on Grain: Corn Consumption Continues to Exceed Projections4-14

    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