ASK THE AGRONOMIST BLOG

Stine’s Ask the Agronomist blog is your source to the latest information from our expert team, including advice and insight on field practices, product recommendations, planting and harvest updates, new technologies, crop management, innovative research and information about how to keep your farm operation running smoothly year round. 

  • Mike Smith Image

    Part 5: Management Strategies for Difficult-to-Control Weeds (Driver Weeds) in Soybeans

    December 05, 2019

    Posted by Mike Smith in Crop Management

    Next in our series of difficult-to-control driver weeds is a much-too-common foe for growers (and allergy sufferers) — giant ragweed. From farmland to roadside ditches, giant ragweed can be found in most areas of the United States. Its size and adaptive nature make it extremely problematic for corn and soybean growers, especially now that it’s developed resistance to glyphosate and ALS-inhibitor herbicides. Learn more about the strengths and weaknesses of giant ragweed and control tactics for this driver weed.

    The Bad News (Strengths)

    • Giant ragweed is extremely prolific. It’s not only capable of producing thousands of seeds per plant, but it also produces pollen at an alarming rate, making it a nasty allergen. According to university weed experts, a single plant can produce 10 million pollen grains per day and one billion during its life cycle. When compared to corn, which can produce around 4.5 million during its life cycle, you can clearly see the prolific nature of pollen production in giant ragweed.
    • High levels of pollen mean increased chances of cross pollination in giant ragweed. When cross pollination transpires, more herbicide resistance can occur when those herbicide-resistant traits are carried over from plant to plant.
    • New populations of giant ragweed are able to germinate and emerge in production fields from March through July.
    • Giant ragweed is extremely competitive and can grow up to 16 feet tall, shading out neighboring crops and competing for the sunlight and nutrients necessary for plant vitality and yield.
    • It is estimated that one plant for every 110 square feet can reduce yield by up to 50 percent in soybeans.
    • Stem-boring insects can be detrimental to glyphosate control of glyphosate-susceptible populations of giant ragweed when applications are made after weeds are 6-inches tall.

    The Good News (Weaknesses)

    • A monoecious weed, giant ragweed grows separate male and female flowers on the same plant. This structure keeps genetic diversity limited to that plant so that it does not pass on that genetic diversity in the form of a mutation to surrounding giant ragweed plants. This slows the development of resistance and cross resistance to multiple herbicide modes of action, allowing for more time to eliminate that genetic mutation before it becomes something we can’t control.
    • No-till systems may have a slight advantage in seed bank persistence because of predation and natural weathering of giant ragweed seeds.
    • Controlling stem-boring insects can have a positive effect on giant ragweed control.
    • Long-term no-till systems combined with adequate herbicide control programs can lead to improved control of giant ragweed populations and significant reduction of giant ragweed seed bank in the soil.

    Management Strategies
    *Note: Current known herbicide resistance includes Groups 2 (ALS) and 9 (glyphosate). There is some known cross resistance between the two groups.  

    • Know your resistance profile. Have your population tested to know what herbicides will be effective.
    • Start clean. Consider tillage and/or an effective burndown to control and eliminate actively growing weeds. Strategies should include multiple effective modes of action for chemical control in burndown. Consult your local agronomist or university extension office for specific burndown recommendations.
    • Utilize an effective soil residual herbicide. Using these products in multiple sequential applications is encouraged, where possible, to delay and diminish the germination and emergence of giant ragweed to allow soybeans a competitive advantage in row closure, canopy and plant density.
    • Utilize an effective post-herbicide program with layered residuals and multiple modes of action. Apply post-emerge applications to weeds less than six inches tall using multiple herbicides for adequate coverage. Follow early-post applications with a sequential application within 14–21 days to control late-emerging plants.
    • Narrow rows. In some cases, narrow-row soybeans may be warranted to increase photosynthetic competitiveness and decrease giant ragweed growth habits.
    • Cover crops. Cover crops have shown an increased ability to lessen seed bank populations and delay emergence.
    • Manual eradication. In severe infestations, manual eradication may be necessary for several years to get the population under control.
    • Conventional herbicide system. Using a conventional herbicide system that relies on multiple, timed passes with soil-applied residuals and effective post-applied herbicides with current broad spectrum herbicides can be an effective strategy. This system is generally costly; however, the increase in yield from reducing weed competition generally outweighs the cost of treatment.

    Trait System Usage
    Use trait systems that provide the ability to apply multiple effective modes of action simultaneously to combat herbicide resistance. For instance, the Enlist E3® system allows Enlist One® with 2,4-D choline to be applied with both glyphosate and glufosinate and additional tank mix partners to eliminate and delay further giant ragweed emergence. This system combines many of the strategies discussed into a flexible platform.

    To learn more about giant ragweed and how to manage this hard-to-control driver weed on your farm, contact your local Stine agronomist or university extension specialist.

     Resources and Citations:

    Biology and Management of Giant Ragweed
    https://weedscience.missouri.edu/publications/gwc-12.pdf

    Management of Herbicide-Resistant Giant Ragweed
    https://weedscience.missouri.edu/publications/FactSheet_GiantRagweed.pdf

    Arkansas Field Crop Weed Control Resources
    https://www.uaex.edu/farm-ranch/pest-management/weed/field-crops.aspx

    Giant Ragweed
    https://iwilltakeaction.com/weed/giant-ragweed

    Super Weeds
    https://u.osu.edu/osuweeds/super-weeds/

    Postemergence Control of Giant Ragweed in Soybeans
    https://agcrops.osu.edu/newsletter/corn-newsletter/2014-20/postemergence-control-giant-ragweed-soybeans

    Palmer amaranth: ID, biology and management
    https://crops.extension.iastate.edu/palmer-amaranth-id-biology-and-management

  • Harvesting Gratitude
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    Harvesting Gratitude

    November 27, 2019

    Posted by Stine Seed in Stine News

    “The thankful receiver bears a plentiful harvest.” — William Blake

    Through the good years and the bad, there is always something to be thankful for. At Stine, we count our blessings every single day that we’re able to wake up, go to work, spend time assisting our grower customers and come home to our families. As we approach Thanksgiving, a time for gathering and for giving thanks, we want to express our sincerest gratitude to all those who have touched our lives. Thank you for being there for us, and thank you for your loyalty and trust in the Stine brand. Here are a few messages of gratitude from our team.  

    “I am thankful for the incredible support from my wife, Jessica, oldest son, Bryce, and our new addition, Wyatt. I am blessed to have this new opportunity with Stine and to have a career that I truly enjoy. I would also like to extend my blessings to my immediate family in Iowa and Saudi Arabia and to my extended family scattered throughout the country." — Tyler Kytola, production

    “I am thankful for all things in life that are beautiful and for everything that brings interest, excitement and accomplishment. I’m extremely grateful to have a supportive family and friends who are always there to offer a helping hand when needed. I’m thankful to be involved with world agriculture, and to be given the chance to make even the slightest difference on its impact toward human progress.” — Myron Stine, president

    “I am grateful that my family is near, and we are able to celebrate the holiday season together. I am blessed to be in a position in my life to give back to others. I am grateful to be surrounded by so many supportive people in all aspects of my life. But mostly, I am thankful for my three boys: Tristan, Mason and Kael.” — Jessica Drake, marketing coordinator

    “I am so thankful for the many blessings God has given me in my life. I’m thankful for my job at Stine and for the great group of people I get to work with on a daily basis. I am thankful for my wonderful family, which includes my parents, two sisters, four brothers and my many nieces and nephews. I am thankful for my loving and supportive husband, Greg, for our two amazing daughters, Makayla and Makenzie, and for our little boy that we will be welcoming into the world in February 2020.” — Tamara Davisson, administrative assistant

    “This year, I am most thankful for my health, family and career. It has been a year of many changes for Dee and me; we made a major move around Christmas last year, leaving our home of 32 years in Indiana to the greater Des Moines area. We have felt welcomed by the communities, church and Stine Seed Company. With all of the changes, it opened opportunities for a lot of stress, but we are both thankful for all of the help we have had in making the many adjustments needed to make this area our new home. We are also thankful for our children and grandchildren and for being a part of their lives.” — Kenneth Wolf, director of training–sales

    “I am beyond thankful for the amazing life and assurance God has given me. I’m grateful for my family, friends, health and happiness. I’m also thankful to work in an industry that hosts the most dedicated, hard-working people that persevere through any challenge. I’m thankful for the opportunities Stine has given me and the relationships that have been built in my time here.” — Bethany Oland, regional sales agronomist

    Happy Thanksgiving from your friends and family at Stine!

  • Mike Smith Image

    Part 4: Management Strategies for Difficult-to-Control Weeds (Driver Weeds) in Soybeans

    November 21, 2019

    Posted by Mike Smith in Crop Management

    This week we resume our conversation on herbicide-resistant and other hard-to-control weeds by examining Palmer amaranth, a prolific, yield-robbing species of pigweed. Palmer amaranth is no stranger to most growers. Its aggressive and productive nature make it difficult to mitigate and highly prevalent throughout the country. Learn the strengths and weaknesses of this driver weed and recommended control tactics.

    The Bad News (Strengths)

    • Female Palmer amaranth plants can produce as many as 750,000 seed per plant.
    • These plants are extremely prolific in growth habit, growing up to 2–3 inches per day.
    • A dioecious weed, Palmer amaranth grows male and female flowers on separate plants, allowing for more genetic diversity in single populations and rapid development of herbicide-resistant genes, including cross resistance to multiple herbicides in the same population.
    • Palmer seed emerges at soil temperatures from 65° to 95° Fahrenheit, so it has a longer emergence schedule than other weeds.
    • The plants produce small seeds that are well adapted to minimum and no-till systems.
    • If left uncontrolled, Palmer amaranth has been known to reduce yields by as much as 79 percent in soybeans. 

    The Good News (Weaknesses)

    • While seed can be viable in the soil for several years, research demonstrates that less than 12 percent of weeds will remain viable for longer than three years, and only two percent of seed will remain viable for longer than six years.
    • Seed in the South is less persistent in the soil than in the North.
    • Seed that is emerging or recently emerged is easier to control than plants that have had the opportunity to grow to 6 inches or greater.
    • Shading, or the inability of growing seedlings to capture sunlight, can greatly inhibit Palmer amaranth’s prolific tendency.

    Management Strategies

    *Note: Current known herbicide resistance for Palmer amaranth includes Groups 2 (ALS), 3 (microtubule inhibitors), 4 (synthetic auxins), 9 (glyphosate),14 (PPO inhibitors) and 27 (HPPD inhibitors), There is some known cross resistance (single population resistant to both Groups 9 and 2).

    • Know your resistance profile. Have your population tested to know what herbicides will be effective.
    • Start clean. Consider tillage and/or an effective burndown to control and eliminate actively growing weeds. Consult your local agronomist or university extension office for specific burndown recommendations. Note that use of burndown products in multiple sequential applications is encouraged, where possible, to delay and diminish the germination and emergence of Palmer amaranth to allow soybeans a competitive advantage in row closure, canopy and plant density.
    • Consider narrow rows. In some cases, narrow-row soybeans may be warranted to increase photosynthetic competitiveness and decrease Palmer amaranth growth habits.
    • Cover crops. Cover crops have shown an increased ability to lessen weed seed bank populations and delay emergence.
    • Manual eradication. In severe infestations, manual eradication may be necessary for a few years to get the population under control.
    • Harvest eradication. In the South, some growers have turned to adding mechanical seed destroyers on combines to control weed seed escapes.
    • Conventional herbicides. Using a conventional herbicide system that relies on multiple passes with soil-applied residuals and effective post-applied herbicides with current broad spectrum herbicides can be an effective strategy. This system is generally costly; however, the increase in yield from reducing weed competition generally outweighs the cost of treatment.

    Trait System Usage

    Use trait systems that provide the ability to apply multiple effective modes of action simultaneously to combat herbicide resistance.  For instance, the Enlist E3® system allows the use of Enlist One® with 2,4-D choline to be applied with both glyphosate and glufosinate as well as additional tank mix partners to eliminate and delay further Palmer amaranth emergence. This system combines many of the strategies discussed into a flexible platform.

    To learn more about Palmer amaranth and how to manage this hard-to-control driver weed, contact your local Stine agronomist or university extension specialist. 

    Resources and Citations:

    Palmer Amaranth Management in Soybeans
    https://extensiondata.missouri.edu/Pub/pdf/miscpubs/mx1125.pdf

    Arkansas Field Crop Weed Control Resources
    https://www.uaex.edu/farm-ranch/pest-management/weed/field-crops.aspx

    Palmer Amaranth (Pigweed)
    https://iwilltakeaction.com/weed/palmer-amaranth

    Pigweeds
    https://u.osu.edu/osuweeds/super-weeds/

    Palmer Amaranth Biology, Identification, and Management
    https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/7/3461/files/2016/01/WS-51-W-1cpo2fz.pdf