A number of folks are seeing a good bit of burn when they have tankmixed Liberty and glyphosate on their Delta and Pine Land cotton. In our research when we have tankmixed those two herbicides indeed we have seen about 20% cotton injury.Some growers see that level of injury and get major heart burn and others take it in stride as the price to pay for managing Palmer amaranth. In our research this spring the cotton with 20% injury had pretty much recovered in 10 days. In other years the recovering has taken longer.
If Dual Magnum or Warrant are also added the injury will go up to 25 or even 30%. That level of injury can delay the cotton but in our research over the past couple years it did not reduce yield.
When Phytogen cotton is sprayed with Liberty we absolutely recommend no other herbicide be added with it due to crop injury concerns. It is best if Delta and Pine Land cotton be managed similarly when the cotton is under stress to avoid maturity delay. This is particularly true when coming out of cold stress as cotton leaf cuticles are even thinner.
The best strategy is to spray Liberty first. Add acephate at his time if needed for thrips control. Then about a week later come back with glyphosate and Dual Magnum tankmixed.
If the cotton is Stoneville I typically have not found much over 15% injury on those varieties with Liberty and glyphosate tankmixes so that is an option. However, if time allows, sequential applications would be a good option as well.
We have also found that cotton leaf burn can be reduced about 10% if nozzles are used that provide course droplets. In other words moving from a flat fan to something similar to a Spraying Systems AIXR or a Wilger DR nozzle did reduce cotton leaf injury without any appreciable loss of Palmer amaranth control. However, with ultra course nozzles like Spraying Systems TTI then Palmer amaranth control will suffer with Liberty.