Pigweed: prevent seed production

Pigweed: prevent seed production

Better farm sanitation must be a part of the equation. Rice as a rotation crop for pigweed management. 2,4-D as a levee treatment in rice. Rope wick applicators and other types of wiping devices. Deep plowing to bury the weed seed. LibertyLink soybeans and Roundup Ready or conventional soybeans.

We must focus on the prevention of pigweed seed production.

How many fields did we all see this summer where the field was relatively clean but the ditches and turn rows around the field were solid Palmer pigweeds? Better farm sanitation must be a part of the equation now.

How many fallow fields did we see where they were eventually disked up but after the pigweeds had set seed?

What weed is becoming the dominant weed around the farmstead or even on vacant lots in small towns or other areas near the farm?

I have a lot of folks asking me about the effectiveness of rice as a rotation crop for pigweed management. I will cover rice in more detail when I get to rotation crops. The short answer though is rice is a great rotation crop — ifyou control the pigweeds on the levees before they set seed.

How many rice fields did we see with 100 percent pigweed control in the paddies and mature pigweeds on the levees?

None of the above statements are intended to be critical of anyone. However, efforts must increase across the board to prevent pigweed seed production. They will simply overpower you with numbers.

Bob Scott wrote a few weeks ago about the need to revisit the regulations for 2,4-D as a levee treatment in rice. I agree completely. This is by far the most effective herbicide on large pigweeds on levees as well as ditch banks and other fallow areas.

Neither science nor common sense support having the same buffer zones and regulations for levee sprays and other types of spot treatments as there are for broadcast applications. Hopefully some dialog can begin among rice and cotton farmer groups with the university and regulatory folks on this issue.

I am getting a lot of questions about rope wick applicators and other types of wiping devices for pigweed control. They are being used in some areas with some degree of success.

There are a couple of problems with them, however. First, by the time you get enough growth above the crop canopy to accomplish much by wiping, much of the competition losses have occurred.

There are a couple of things here I never dreamed we would talk about again given the technology we have. One is wiping devices and the other is revenge weed control. We are going the wrong direction.

The other problem with wiping is it may knock the weeds back and make you feel better but often will not prevent seed production. We must have programs to kill them before they get to the wiping stage.

Some are asking about deep plowing to bury the weed seed. I even hear some talking of looking for moldboard plows. Again, who would have thought it? I think there is some merit to deep plowing and inverting the plow layer in some of the heavily infested areas. Burying the weed seed deep can have an immediate reduction in the plant population.

What do you do from there? If you use the immediate reduction to begin a zero seed production program, the plowing may have a benefit. However, if you let any significant amount of the weeds that emerge the next year produce seed, you can be right back where you were in one year.

A lot of growers are feeling much better about their pigweed control programs this year than last. Some have planted LibertyLink soybeans and some have done a much better job in Roundup Ready or conventional soybeans. However, a lot of these fields have a uniform scattered infestation of pigweeds going to seed. If you use the wrong program next year or if the weather does not cooperate on residual herbicide activation, you can be back to square one.

The prevention of seed production must become a big part of our pigweed control program to make some of the older programs viable and to preserve the new technology such as LibertyLink coming along.