Several things presented in the weed control session at the recent Rice Technical Working Group meeting caught my attention.
A couple of new pre-emergence herbicide candidates for broadleaf weed control are being evaluated. Maybe one or both will eventually work out.
While barnyardgrass resistance is my greatest concern in rice, most weed control questions I get are about broadleaf weed control — especially from areas where 2,4-D cannot be used.
LSU presented some information on pre-emergence activity from Permit. I saw some of this in Dr. Eric Webster's plots last year at the LSU field day. He has seen pretty good pre-emergence activity on some of the broadleaf weed complex as well as some pre-emergence activity on barnyardgrass with labeled rates of Permit.
Some recent work done with this herbicide indicates a lot of us may have spent too many years considering it primarily as just a nutsedge herbicide.
I feel more research is needed before we begin recommending a lot of Permit as a pre-emergence herbicide.
In a lot of the areas where 2,4-D cannot be used, when I am asked what can be used for coffeebean and indigo that has some residual, my standard recommendation has been Facet or Quinstar. However, in some of the worst fields, the research indicates it may be worthwhile to look at a labeled rate of Permit in front of a flush or the flood for residual control. If any broadleaf weeds are emerged, add some propanil to make sure they are not missed.
A paper presented by Dr. Jason Bond and others from Mississippi State University caused me some concern. They were consistently getting a yield reduction where they were applying Facet postflood in weed-free rice — without seeing any injury symptoms. They did the research in response to some grower complaints where they pretty much ruled out everything but the Facet application as being the problem.
They conducted the research across a range of varieties and got more yield response on some varieties than others. The reason it causes me concern is I have routinely recommended Facet postflood since it has been registered and have never worried about how late the application was as long as it was within the labeled pre-harvest interval.
In a field situation, of course, it is not being applied to weed-free rice. Therefore, the yield gain from controlling the weeds may more than offset any potential loss from herbicide injury.
If subsequent research backs up these early findings, other herbicides can be considered before deciding if postflood Facet is needed.
One would think that in as much Facet research as has been conducted through the years, we would have found this before now if it is a consistent problem. This research further makes my point that barnyardgrass needs to be controlled before flooding. While there will always be “slip ups,” not much good happens in salvage weed situations.
Last week I promised more information on how to order the rice seedling weed schematic from LSU. On the Internet, Google “weed schematic” and you'll get a link to it. When you open it, you can print it. Or there is a link to click to order. It can also be ordered over the phone by calling LSU Ag Center publications at (225) 578-6598.
Bob Scott has ordered copies of the publication that will be available through Arkansas county Extension offices.
You can tell that I like good picture publications. I did several while I was a university guy, including one on seedling weeds. However, this little publication is the best seedling weed guide I have seen for rice.