Few would argue that herbicide diversification is a bad thing. But increasing the number of available herbicide modes of action does increase the risk of inadvertently causing herbicide damage, whether through drift, carryover issues or even outright misapplication, says Isaac Ferrie, Crop-Tech Consulting, Inc.
Sherlock Holmes once quipped, "There is nothing like first-hand evidence," and Ferrie says farmers must strike a similar attitude if they want to properly diagnose any mystery herbicide damage. That means they must make two important observations before they make any sound conclusions.
(Click here to take the Herbicide Damage Photo Quiz from 2013 Corn College.Then click here for answers to the quiz. Mode of action name and site of action number are listed. For your reference, a more complete list of herbicide modes and sites of action is available here.)
First, look at the whole field, Ferrie says. The pattern of damage distribution can reveal a lot about what caused it. For example, damages limited to field borders and edges are often drift-related. If the entire field is affected, misapplication could be the culprit.
Second, look at where the damage is occurring within the plant. Is it on leaves? Roots? Old growth? New growth? Each site of damage is a clue to take into consideration, Ferrie says.
"For example, if the damage has translocated into new parts of the plant, it’s a systemic herbicide you’re dealing with," he says. "If it’s only in the old growth, it’s a contact herbicide."
Specific plant damage will further delineate what mode of action you should suspect. Farmers should also have the following information handy to make the best diagnosis:
- Variety/traits planted.
- Herbicides sprayed on the field last season.
- Herbicides sprayed on the field this season.
- Herbicides sprayed in adjacent fields.
"It’s important to take good notes – not just for your safety, but also for your neighbor’s safety," Ferrie says.
Thank you to the 2013 Corn College sponsors:
AgriGold, BASF, Chevrolet, ESN/Agrium, Great Plains, Honeywell, Koch, Novozymes, Precision Planting, SFP, Top Third Marketing
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