Planting time is rapidly approaching and I am concerned about our level of preparedness for dealing with Palmer Amaranth in our cotton production. Many of you may know these weeds have been found to be resistant to the herbicides Roundup and Staple which have been the keystone of a cotton herbicide program. I was scouting some fields on April 11 and can find Palmer Amaranth that is already 4” tall. I have several concerns: 

Concerns

1. Do not knock down beds or strip-till and plant without terminating emerged Palmer Amaranth. If you try to shortcut this step, you will bury weeds and not have any opportunity to kill them again.
2. We do not have any other reliable herbicides to kill this in-crop. We only have preventive herbicides.
3. If you let these 4” pigweeds go 3 more weeks before spraying, they will be too large to kill with any our pre-plant herbicides even at max rates.
4. We need 21 days between the application of 2,4-D and planting cotton.
5. Some of you are planning to rely on Ignite based programs. I have watched farmers in our neighboring counties miss Palmer Amaranth over and over because it is virtually impossible for the diversified farmer to catch these weeds before they are 5” tall, at which time Ignite is ineffective due to weed size. Practice these same early season recommendations.

We have very good herbicide programs available if you will use them appropriately. I have several early season recommendations that are very straight forward to get you started.

Recommendations          

1. Spray Gramoxone/Parazone/Firestorm (rate depends on formulation and weed size) plus 1% crop oil the day before knocking down beds and planting. We cannot kill weeds buried during bedding. 
2. If you will not be planting for 3-4 weeks or more. Use the Gramoxone early on weeds less than 8” tall. If you have more than 10 days before planting, you can add 1 oz of Valor for residual. You must still come back and do recommendation 1 above before planting.
3. Within two days after planting, apply 12 oz Reflex and 16 oz Diuron BEFORE cotton and weed emergence.

It is critical in cotton production that we do these things right, or we will be paying for hand weeding, and potentially losing fields. I say that based on my experience and the level of weed emergence I am already seeing. Please contact me at the Extension Office if I can be of assistance. I have attached more information.

UGA Programs for Controlling Palmer Amaranth in 2013 Cotton

2013-Cotton-Herbicide.pdf 

University of Florida EDIS “Palmer Amaranth”

Palmer-Amaranth-EDIS