I just returned from the Conservation Tillage Cotton and Rice Conference in Tunica, Miss. I always enjoy that meeting, especially the farmers' presentations.
Most of the sessions pair a university guy and a farmer making presentations on a topic. I can tell you as a university guy paired with a young farmer several years ago at that meeting: if you aren't careful, a farmer can blow you out of the water.
I was asked to moderate a round table discussion on rice weed control. Several interesting topics were brought up.
I touched on one of the topics in my last column — making sure you get any glyphosate-resistant or glyphosate-tolerant weeds such as marestail or horseweed, cutleaf evening primrose and, in some cases, volunteer Roundup Ready soybeans cleaned up before planting.
This is usually accomplished by adding 2,4-D to an early burn-down application. The reason you have to consider these early is you cannot apply 2,4-D too close to planting. Most of the time, you can get by with a 14 day interval between a 2,4-D application and planting. I have even seen it done successfully on a shorter window on occasion.
The degradation rate is not always the same, and if there is a significant amount of 2,4-D still around at planting, rice injury can be severe. This risk can be avoided totally by planning ahead.
Another topic was on controlling some of the non-traditional rice weeds such as pigweeds and ground cherry. These weeds can be controlled easily when they are small, but they are very difficult when they are larger.
I like spraying Aim on ground cherries when they are still in the rosette stage on top of the ground. Almost any rate will just turn them to tissue paper. Once you let them get fleshy stems, they are near impossible to kill.
Some interesting information was presented on levee weed control that ties in with some comments I want to make about quinclorac (Facet or Quinstar). Levee weed control in general is often much easier when quinclorac has been applied as a pre-emergence herbicide. This is especially true on ground cherry, but there is usually just less weed pressure when a pre-emergence herbicide has been used.
Bob Scott also reported that some work done on quinclorac-resistant barnyardgrass has shown the resistant biotypes to be much more susceptible to pre-emergence applications of quinclorac than to postemergence applications.
In addition, concerns were voiced by farmers about high pumping costs and how to reduce them. The proper use of residual herbicides can lengthen the weed-free window and often allow you to delay the flood.
It just as if barnyardgrass in general is getting much more difficult to control with all herbicides once it gets up and going.
When you combine all of the factors listed above, you have most of the reasons I recommend a lot of quinclorac right behind a Command application whether there are any weeds up or not. Pick some of your fields with a history of difficult weed control and try a pre-emergence application of Command right in front of a rain or flush and then come right back with a half-pound of quinclorac right in front of the next rain or flush.
If some grass is up, add Ricestar HT or a propanil such as Super Wham. If you can get an application of Command and an application of quinclorac activated before much of anything is up, you will have better grass control, better levee weed control and a longer residual period.
It takes a little faith to run a half pound of quinclorac when you do not see any weeds up. You know they will be coming, so you are not wasting money and it can make things much easier. Try it and I believe you will like it.