In several recent articles, I have referred to a potential 24-C registration to allow other herbicides to be tank-mixed with Command and applied postemergence. That label has been issued and allows the following herbicides to be tank-mixed with Command: Aim, Clincher, Duet, Facet, Propanil, Regiment, Ricestar, Roundup Ultra Max, Stam, Super Wham, as well as crop oil concentrate and non-ionic surfactant. It should be noted that only the approved products specifically listed on the label may be used.
The procedure required by the Arkansas Plant Board is that a series of approved studies must be conducted to insure that the product proposing to be tank-mixed will not alter the spray droplet size in a negative way. These studies are required before a petition will be considered.
The study or studies involve Dennis Gardisser, University of Arkansas agricultural engineer, working with an aerial applicator to apply the treatments across water-sensitive and dye-sensitive cards. Visual observations are made on the spray behavior, and then Dennis analyzes the droplet size spectrum on the cards to determine if the tank-mix being tested is producing any finer droplets than the Command alone.
The products listed earlier passed and were approved by the Plant Board. Two products — Arrosolo and Clearout 41 Plus — were tested and did not pass. It is possible these could be re-tested at a later date.
I am aware that several other tank-mixes have recently been tested, but no decision has yet been made on them.
The tank-mix label greatly expands the flexibility of Command as a rice herbicide. I prefer to use Command as a preemergence herbicide, but the weather does not always cooperate, and different situations require different treatments.
The Roundup Ultra Max label allows Command and Roundup to be tank-mixed in reduced tillage situations. Unfortunately, that is the only glyphosate labeled and it is being replaced by Roundup Weathermax. Studies have been conducted on it and several other glyphosate products and I hope they can be added soon.
If the weather is dry at planting and the forecasts are for continued dryness, delaying the Command application makes good sense. If weeds have emerged at the time of application, choose one of the tank-mix options that best fits the emerged weeds.
One of the propanil products will fit a broad spectrum situation. Ricestar or Clincher can fit nicely where the weeds include sprangletop or propanil-resistant grass, or where sensitive broadleaf crops are nearby.
Even though Command has mostly residual activity, I often see an increase in postemergence activity when it is added to propanil, Ricestar or Clincher compared to the same herbicides alone. Keys to success with these treatments are small grass, good moisture at application to insure good postemergence activity, and additional moisture to activate the Command.
Ford Baldwin, Practical Weed Consultants. e-mail: [email protected].