May 27, 2009
To say this is a “throw the book out” year in rice weed control is an understatement.
Most of the calls I’m getting have a common theme of rice either having been under water or rice that has stood in water for long periods with big grass in it.
Last week I wrote that this is going to be a sprangletop year and a Ricestar HT year because that herbicide fits many of those situations well.
There has also been another common theme to and that is ducksalad. Ducksalad is a warm, saturated-soil germinator. Normally in dry-seeded rice, the rice is planted in April, it gets a jump on the ducksalad in the dry soil, and it just grows off and leaves any ducksalad that may emerge.
While it can be a problem in levee ditches, it is uncommon to need to treat ducksalad in the paddies in dry-seeded rice.
In water-seeded rice, ducksalad is a major problem. It usually gets the jump on the seedling rice because it has a chance to germinate first with the water on the field.
In much of the rice that has been planted to date this year, the soils are warmer, they have been saturated or under water for long periods, and the rice has struggled to get established. As a result, we have a water-seeded scenario in a lot of dry-seeded rice.
In addition, some fields that would normally be dry-seeded have been water-seeded because the growers gave up on getting them dry.
Consultants call saying, “Ford, I have never seen ducksalad this bad.” Whether the rice is water-seeded or dry-seeded, when ducksalad gets the jump on the rice, it is an aggressive competitor.
Herbicides that have good ducksalad activity include Londax, Regiment and Grasp. Others that can make good tank-mix partners include Duet, RiceBeaux and Storm.
In Clearfield rice, two applications of Newpath can provide suppression, but this year it will need some help in a lot of fields. Beyond has much better postemergence activity on ducksalad than Newpath.
Londax has pretty much become a forgotten herbicide — until this year. I have heard more than once, “This is going to be a Londax year.” I usually recommend Londax for ducksalad control early in the season — especially where the rice has struggled. However, I do not recommend it alone.
Where Command was not applied, Command plus Londax and oil can be a good treatment on small ducksalad.
I have also recommended Duet plus Londax and RiceBeaux plus Londax early.
In Clearfield rice, I do not remember recommending Londax in the first Newpath application before this year.
RiceBeaux plus Newpath can also make a nice first application in Clearfield rice where small ducksalad is present.
In many of the early situations this year, the challenge has been to do as much as you could for the larger grass and ducksalad while being as easy as possible on the struggling young rice. Once the rice recovers from the water stress, gets well-established and reaches the three-leaf to four-leaf stage, it is time to be more aggressive.
There are going to be a lot of fields with bigger ducksalad, smartweed and barnyardgrass that likely escaped the first treatment. Regiment will be a nice fit there. The combination of those three weeds make an ideal Regiment situation.
Grasp can be more erratic on barnyardgrass and smartweed, but it is an outstanding ducksalad herbicide. Where ducksalad is the major problem, Grasp is an excellent choice.
I have also killed a lot of large smartweed and ducksalad through the years with propanil plus Storm, but you do not want this treatment on sick rice.
In Clearfield rice where big ducksalad is present, Beyond with a low rate of Grasp in it is wicked. My definition of small ducksalad versus big ducksalad is pretty much when it starts to “spoon.” When it is flat on the soil surface with the “grassy-looking leaves” Londax mixtures are often the best choices because the rice is usually smaller.
As the ducksalad begins to spoon and the rice gets larger, Grasp and Regiment become better choices.
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