For a lot of years I preached economic thresholds for weed control — trying to spend only enough to make an optimum yield.
I thought it was a good idea at the time, and while it is a great principle for insects and diseases, it is a bad idea for weed control. With the rapid spread of herbicide resistance, you must strive for 100 percent control if you are into farming for the long haul.
In rice the most economical programs usually begin with overlapping residual herbicides. Command or clomazone remains the base soil residual program, but I like getting two different residual applications out prior to emergence.
There are a lot of examples, but something like a Command or clomazone pre-emergence followed by Prowl or one of the generics plus Facet or one of the generics. Or one of these herbicides with Bolero or RiceBeaux.
Some ask, “Why can’t I just load up on Command and Facet at planting and save a trip?” That is an option. It is a pretty popular treatment and some even add League to it for broadleaf control.
I favor a split pre-emergence followed by delayed pre-emergence treatment to allow two different shots at activation if you won’t flush. It extends the length of residual, and it provides the opportunity to include more modes of action.
The Prowl and Bolero treatments can only be used after the rice seeds have imbibed germination water.
Some say, “You sure are asking me to spend a lot in a year of tight money before I see any weeds!”
I am, but as I have observed what is happening in the rice verification fields and with the consultants that call me a lot, those who are staying in the $50 to $60 per acre on herbicide costs are the ones loading up with residuals on the front end.
Most are struggling more and more trying to control grasses and in some cases sedges once they emerge. Normally it will take a preflood cleanup treatment preflood, but the goal at that point is to be shooting cripples.
When you get into a firefight postemergence, herbicide costs can go over $100 per acre in a hurry.
Ford Baldwin served as a weed scientist with the University of Arkansas Cooperative Extension Service from 1974 to 2001. Since 2002, he has been a partner in Practical Weed Consultants with his wife, Tomilea. Contact him at [email protected].