Alabama Cotton: Dirt Cheap Weed Control? Don’t Go Too Far.

Photo: Debra L Ferguson Stock Photography

Photo: Debra L Ferguson Stock Photography

Cotton commodity prices have plummeted over the last weeks and are now at or well below the cost of production. Looking for ways to survive, some growers are thinking about a “dirt cheap” way to manage this crop. In such situations, chemicals and fertilizers are typically among the first inputs to reduce.



I don’t oppose cutting back, but I am concerned that overly reducing weed control efforts could seriously affect future operations. Weeds are persistent problems and cannot walk or fly away from a field or farm.

One year of sloppy pigweed management can result in significant expense for clean up over the next 3 to 5 years.

I’ve had a few calls with growers requesting a “dirt cheap” weed control plan for cotton and peanut. Here are my thoughts about maintaining sufficient weed control but not at a higher costs.

Burndown:

  • For marestail fields, Roundup + Sharpen 1oz/A.
  • For no-till or conventional till cotton fields, Roundup + Valor 2 oz.
  • For generic glyphosate, add NIS surfactant at 0.5 gallon per 100 gallons of spray solution.

PRE (from 3 days before planting to 3 days after planting):

  • For pigweed and grassy fields, Warrant 3 pt/A.
  • For fields general broadleaf weeds like pigweed, sicklepod, morningglory, teaweed, etc., Cotoran 2 pt/A.
  • For heavy pigweed and grass pressure, Reflex 8 oz + Warrant 2 pt/A is a great choice.
  • For PRE herbicide activation, a 0.5 inch rainfall is needed for activation.
  • Add 2 pt of Gramoxone if weeds have emerged at planting.

For pigweed fields:

1st POST over the top of cotton (at 20 to 25 days after planting):

Roundup PM 32 oz + Xtendimax / Engenia (Xtend Cotton) or Enlist One (for Enlist Cotton only) + Warrant 2.5 pt or Dual Magnum 16 oz or Outlook 13 oz or generic version of Group 15 herbicides.

Timing is absolutely critical. Treatments should made when weeds are less than 3 to 4 inches tall. As soon as pigweed can be seen on the ground, get your sprayer ready and spray them.

Follow-up Post or Layby:

If 1st POST applications for pigweed were made in a timely manner and if residual herbicides from Group 15 (Warrant, Dual, Outlook or generics of these herbicides) have been activated by rainfall, then apply Valor 3 oz or Cotoran 2 pt/A about 2 to 3 weeks later using a layby, hooded, or post-direct sprayer.



Cotton needs to be at least 10 to 12 inches tall to minimize crop damage. Use a coarse droplet nozzle if possible. If some pigweed survived 1st POST, spot spray Liberty or a generic glufosinate and then follow with the layby, hooded, or post-directed treatment.

Two generic glufosinate products Scout from Valent and Interline from UPL performed equally to Liberty in trials last year. Liquid AMS has shown promise in enhancing the control of large sicklepod and pigweed with Liberty (glufosinate).

The game plan is simple. Try to start clean, spray everything timely, and use plenty of cheap residual herbicides in PRE, 1st POST and Layby applications. Try to avoid a 2nd POST broadcast over-the-top using more expensive POST herbicides.

If we don’t run out of rain and if growing conditions remain mostly normal, I am hoping to get through in-season weed management within $30 per acre.

Don’t forget to cut off pigweed seedheads before picking cotton!!! Pigweed produces too many seeds per female plant — we cannot ignore them.

For fields without pigweed:

1st POST over the top (at 20-25 days after planting):



Roundup PM 32 oz + Warrant 2.5 pt/Dual Magnum 16 oz/Outlook 13 oz/or a generic of these herbicides. Add liquid AMS to enhance control of large broadleaf weeds and nutsedge. Use 2 oz of Staple LX if morning glory and nutsedge have been problematic in the past.

After 2 to 3 weeks, if fields remain mostly clean and cotton is over 12 inches tall, apply Valor 3 oz or Cotoran 2 pt/A in a hooded, post-direct, or layby sprayer. If some weeds survived 1st POST, spray Roundup again to finish them up.

Spot spray pigweed or morning glory with Liberty. Then follow with the hooded, post-directed, or layby application.