THE NEXT THING: PP WEED MANAGEMENT STRATEGIES
Nov 14, 2019
As bad as many of the current Prevent Plant (PP) acres looked by season’s end, what you don’t see may be the worst aspect about them. “There’s no doubt we’re going to have to consider what kind of a weed seed bank is now in those acres,” says Agtegra Agronomy Technical Services Manager Brad Ruden.
Many PP fields may have initially had some weed control management. But it’s been a season of one weather event after another. Poor field conditions prevented timely weed control follow-ups. From kochia to water hemp to many other prolific weeds, the potential for tremendous seed production is pretty much a sure thing. “We’re going to have a big job in front of us, managing a weed population that is going to be extensive,” says Ruden.
If possible, Ruden recommends a fall residual application. “Fall application is not a replacement for a spring application, it’s an add-on that will help us buy some time and begin the recovery of that field,” says Ruden. “A fall residual has tremendous value holding down the weed population long enough in the spring to allow us some time before weeds really take over.
Product-wise, Valor® has been an extremely effective fall-applied herbicide. Note that it is not labeled for use once the ground is frozen. The tank-mix addition of Metribuzin contributes another pre-emerge mode of action, further improving the overall effectiveness of this strategy on PP acres.
The point of these pre-emerge products, says Ruden, is about getting a jumpstart. “Weeds are always going to be easier to control pre-emerge or when they’re small,” says Ruden.
Unfortunately, the time may have passed for that fall Valor® application window, with the recent November snow and cold temperatures. But if there’s any small window of opportunity yet this fall, take advantage of it, urges Ruden.
There are some issues to keep in mind with PP acres this spring, says Ruden. First off, anticipate another round of early wet fields and the resulting effects from those conditions. They are also going to be teeming with weeds, if fall residual was not applied.
“We’re going to see those fields come to life with kochia growth as soon as the snow has melted, if Valor® was not applied during fall,” says Ruden. “That battle to get ahead of weeds is going to be on.” Wet spring conditions are going to start the challenge all over again, but as best we can, be early with a burndown weed control program
Next up, says Ruden, is figure out what crops will best fit those PP acres. “Soybeans can be a little more difficult for weed control on PP acres, compared to corn,” says Ruden. Be sure to plant a trait package with a strong post-emergence herbicide option.
For both corn and soybeans, that fall Valor® application does not replace the need for a spring residual application. “These fields are going to require a full dose of a pre-emerge herbicide,” he says. Then come back in-crop with the next round of protection. “Count on continuous weed pressure as you manage them back into production,” says Ruden.
Corn on past PP acres can be a little easier for managing the weed pressure, especially if fall-applied burndown was used. Spring burndown and residual programs will all be part of weed control management, for corn going back into last year’s PP acres. We have strong residual options in corn, and good post-emergence options as well as a dense, tall crop canopy to hold back later weeds.
The bottom line, says Ruden, is getting ahead of the weeds. “Otherwise we’re fighting an uphill battle all season and beyond, really. We can do various post emergent weed strategies, if we have the right trait system out there. But we have to consider the value in residuals. It’s going to be tremendously important to hold down that weed population, allowing us that extended time to get back in and get fields cleaned up.”