Halls, Tenn., cotton farmer Eugene Pugh says he uses a few gallons of liquid nitrogen in the tank with Diuron to clean the tips. We mix Roundup with Diuron and it seems to work well keeping the tips clean.

Ferguson added that simply cleaning the spray tank and running clean water through it at the end of the day will usually keep the nozzles clean enough to handle gumming problems with urea-based herbicides.

Cover crops

In response to a question about the use of cover crops to manage herbicide resistant pigweed, York quipped, “In my research I don’t like to work with cover crops, because there’s not as many weeds in those fields.”

“There is no doubt cover crops can suppress weeds. The question is what weed suppression advantage am I getting versus some other aggravation that comes into play,” York says.

“Looking at cover crops that get several feet tall, then these are cut and rolled, researchers are getting about 50 percent suppression in Palmer amaranth emergence,” York says.

Recent research at the Tennessee Valley Agricultural Research Station in Belle Mina, Ala. showed that cover crop residue is very effective for controlling pigweed. The rye

was planted at three different dates in late fall and allowed to grow through the winter and early spring before being  killed and rolled prior to planting a cotton crop.

The earlier-planted rye produced greater residue and was most effective at controlling pigweed density (and pigweed biomass). Treatments with winter fallow and traditional tillage (multiple disking) had greater pigweed density (and pigweed biomass).

New herbicides

When asked about new herbicides coming along in the next few years to help manage Palmer amaranth, York says, unfortunately the answer is no.

“If new chemistries that control pigweed are in the pipeline, they are far enough down the pipeline I don’t now about it,” York says. “There are new products and new names that come on the market. Products are pinched together and some new twists on using currently available chemistries are coming and will help, but not a revolutionary new product,” he adds.

“Realistically, the only thing we see on the horizon is 24-D and dicamba resistant cotton. New modes of action are so rare and so expensive to get to the market place that they just aren’t happening.”

Cotton growers attending the meeting were a part of the Monsanto/Deltapine New Product Evaluator program. These farmers grew 20-acre test fields of various research varieties of cotton being developed by Deltapine for distribution in the 2011 season.