Pulse School: Patience is a virtue when it comes to herbicide efficacy

As most, if not all, producers are currently spraying for weed control, it’s important to keep in mind herbicide efficacy, according to Bethany Wyatt, senior technical service specialists for BASF in Saskatchewan. Wyatt says almost every year some farmers will get impatient, and “jump the gun” when it comes to re-spraying.

In this episode of the Pulse School Wyatt explains a person has to wait it out in order for the herbicide to work, especially when it comes to pulses.

“It’s a difficult thing when you apply a herbicide, you expect to see the weeds controlled, relatively quick,” she says. “But we have to remember that within pulses especially, the actives that we are using do take a little bit longer and we need to sometimes just be a little more patient and then especially under these dry conditions, it can take a little bit longer than on a good growing year.”

Wyatt can’t stress enough that the amount of time since a person sprayed, to when a person assesses the crop, is the first thing a farmer should take into account.

“In pulses we’re mostly dealing with the Group 1 graminicides, and the Group 2s and they do just take a little bit longer.” (story continues below player)

When scouting after a Group 1 spray, symptoms to look for include: chlorosis or yellowing of the newest leaf, however, complete efficacy could take up to two or three weeks. At that time, you should be able to pull the newest leaf cleanly from the sheath and check for a dead growing point.

“It’ll be pinched off, brown at the end, then you can be sure that the grassy weed is going to die,” she says. “The newest leaves may yellow, and your oldest leaves might still be green, but as long as that growing point is brown, pinched off, you can pull it out easily — rest assured that weed is going to be controlled.”

As far as Group 2s go, Wyatt says rapid initial stunting should happen quite quickly; however, complete death could take two to three weeks just like the Group 1 actives. Other visuals would be reddening or purpleing at the growing point, and could also have yellowing or even striping.

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