Pick up know-how for tackling diseases, pests and weeds.
Farm bill, farm marketing, agribusiness webinars, & farm policy.
Find tactics for healthy livestock and sound forages.
Scheduling and methods of irrigation.
Explore our Extension locations around the state.
Commercial row crop production in Arkansas.
Agriculture weed management resources.
Use virtual and real tools to improve critical calculations for farms and ranches.
Learn to ID forages and more.
Explore our research locations around the state.
Get the latest research results from our county agents.
Our programs include aquaculture, diagnostics, and energy conservation.
Keep our food, fiber and fuel supplies safe from disaster.
Private, Commercial & Non-commercial training and education.
Specialty crops including turfgrass, vegetables, fruits, and ornamentals.
Find educational resources and get youth engaged in agriculture.
Gaining garden smarts and sharing skills.
Timely tips for the Arkansas home gardener.
Creating beauty in and around the home.
Maintenance calendar, and best practices.
Coaxing the best produce from asparagus to zucchini.
What’s wrong with my plants? The clinic can help.
Featured trees, vines, shrubs and flowers.
Ask our experts plant, animal, or insect questions.
Enjoying the sweet fruits of your labor.
Herbs, native plants, & reference desk QA.
Growing together from youth to maturity.
Crapemyrtles, hydrangeas, hort glossary, and weed ID databases.
Get beekeeping, honey production, and class information.
Grow a pollinator-friendly garden.
Schedule these timely events on your gardening calendar.
Equipping individuals to lead organizations, communities, and regions.
Guiding communities and regions toward vibrant and sustainable futures.
Guiding entrepreneurs from concept to profit.
Position your business to compete for government contracts.
Find trends, opportunities and impacts.
Providing unbiased information to enable educated votes on critical issues.
Increase your knowledge of public issues & get involved.
Research-based connection to government and policy issues.
Support Arkansas local food initiatives.
Read about our efforts.
Preparing for and recovering from disasters.
Licensing for forestry and wildlife professionals.
Preserving water quality and quantity.
Cleaner air for healthier living.
Firewood & bioenergy resources.
Managing a complex forest ecosystem.
Read about nature across Arkansas and the U.S.
Learn to manage wildlife on your land.
Soil quality and its use here in Arkansas.
Learn to ID unwanted plant and animal visitors.
Timely updates from our specialists.
Eating right and staying healthy.
Ensuring safe meals.
Take charge of your well-being.
Cooking with Arkansas foods.
Making the most of your money.
Making sound choices for families and ourselves.
Nurturing our future.
Get tips for food, fitness, finance, and more!
Understanding aging and its effects.
Giving back to the community.
Managing safely when disaster strikes.
Listen to our latest episode!
Marestail control options for corn and cotton
By: Tom Barber, Extension Weed Scientist
Many calls coming in on marestail (horseweed) control this week such as: “What can
I spray and plant immediately,” or “It’s up with my crop, now what”?
The majority of horseweed in Arkansas is resistant to glyphosate and has been since
2006. It is allelopathic to most crops grown in Arkansas and if left uncontrolled
the first 8 weeks can cause significant yield losses. Large horseweed is very difficult
to control. If the field is covered from one end to the other with >8 inch horseweed,
it will likely be cheaper to run the disk and delay planting than to blow the budget
for 60% control and fight it all year long. Most of these calls and pictures indicate
that the horseweed we are dealing with is 4-6 inches tall.
In Corn: If not emerged, 10 oz/A of Verdict with either Roundup or Gramoxone is a good option.
It works better in front of corn than soybeans or cotton, because of the increased
rate of Verdict allowed, and no plantback restrictions to Verdict in corn. If corn
is up, it becomes a little more difficult. This is generally the time where I would
recommend adding 0.25 lb ai/A approved dicamba (equivalent to 11 oz/A Xtendimax) to
the POST mixture of atrazine plus Capreno, Halex GT etc. Due to the current dicamba
restrictions in Arkansas, this application becomes more difficult to recommend. However,
applications of an approved dicamba formulation such as Xtendimax can be made if all
labeled tankmixing rules are followed. Keep in mind that glyphosate is no longer a
labeled tankmix partner for any dicamba formulation after April 15th in Arkansas.
Standard corn programs such as Halex GT plus 1.5-2 qrts/A of Atrazine will provide
decent control of emerged horseweed that is 4 inches tall or less. Adding Liberty
(glufosinate) to the POST mix is another option and will improve control, but make sure that the corn hybrid planted is Liberty Link before making the application.
Resicore, a mixture of acetochlor, mesotrione, and clopyralid, is a newer alternative
that has a good fit for horseweed in corn that’s less than 12 inches tall. The suggested
rate based on our experience is 40 oz/A, make sure you read the label because there
are planback restrictions, including a 12-month plantback interval to cotton.
The final option in corn is to add 16 oz/A 2,4-D to your favorite POST herbicide mixture,
but the ability to use this herbicide is dependent on where you farm in the state.
Be sure to read and follow all State Plant Board rules prior to making applications
of an approved dicamba or 2,4-D formulation.
In Cotton: Prior to May 25th, an approved dicamba formulation (Engenia, Xtendimax, etc.) can
be applied any time prior-to, or at-planting, or POST in Xtend cotton as long as Arkansas
State Plant Board and Federal Label rules are followed. Since other species may be
present prior to cotton emergence, Gramoxone plus one of the PSII inhibitors such
as Caparol, Cotoran, or Diuron is most likely the best option on small horseweed with
these cooler temperatures. Liberty will become a better option after emergence or
once daily highs move up in the 80’s. When the cotton reaches 5 true leaves, Envoke
can be used. Envoke has really good activity on horseweed but cotton injury can be
more severe if sprayed prior to the 5-leaf stage.
As always be sure to reference the herbicide product labels prior to making applications
and the MP44 for further suggested herbicide alternatives. Wishing everyone a safe and healthy
planting season, call us with questions.