Use of Command to control weeds in rice has declined slightly since its first full year of use, but the herbicide remains a widely used first step. For the money, no other pre-emergence herbicide offers the broad-spectrum residual grass control that Command does.
In addition to pre-emerge applications by ground, FMC company also has a label (for Arkansas only) that allows aerial applications of Command alone up to seven days after planting or in a tank mix with a postemerge product up to the one- to two-leaf stage of rice. The special Arkansas aerial label specifically names as tank-mix partners: Aim, Clincher, Duet, Facet, propanil, Regiment, Ricestar, Roundup Ultra Max, Stam, or Super Wham.
FMC was somewhat reluctant to promote applications of Command by air and in these tank-mixes. Command is already used on a large number of acres and drift has not been a problme with ground applications.
The Arkansas Plant Board and FMC, however, recognize management issues associated with making ground applications. Safe application by air is of benefit to farmers. One of the main reasons that such use is possible is the well-trained aerial applicators we have in Arkansas. I believe they are some of the best in the country.
In our research last year, postemergence applications of Command tank-mixed with a grass material such as Clincher, RiceStar or Super Wham performed as well or almost as well as Command followed by a pre-flood application of the same post grass material. Only slight reductions in barnyardgrass were observed if the post-applied tank-mix partner with Command failed to control a little grass.
This early-post option offers the benefits of making one application instead of two, and it may be possible to extend the period of residual control you get out of Command by delaying the applications for a week to 10 days. It may also give you time to pull your levees prior to application, resulting in better grass control on your levees. You may be in a better position to flush to activate your herbicide at this time.
I have encouraged growers to try this total post Command program on a few acres this year before trying it on the whole farm.
Command rate is based on soil type. Command use should be avoided on cut soils. On our silt loam soils at Stuttgart and Lonoke, Ark., where I conduct most of my weed control studies, we regularly get good weed control and acceptable crop injury with 0.3 pound active ingredient per acre (or 0.8 pint per acre).
On the clay soils at the Southeast Research and Extension Center near Rowher, Ark., Ken Smith can use up to 0.6 pound active ingredient per acre (or 1.6 pints per acre) without fear of unacceptable injury.
We are experimenting with split shots of reduced rates of Command applied both pre and post this coming year and more tank mixtures are also being evaluated.
Command is an economical product that will not work properly without a rain or flush for activation. I understand why no one wants to flush. It does, however, make my job easier as a weed scientist when we do not have to go after big grass that has escaped an application of Command early in the season. That is money we cannot get back.
The most expensive weed control program is the one that does not work.
Bob Scott is the University of Arkansas Extension weed specialist. [email protected].