Fomesafen Carryover into Corn and Grain Sorghum

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Carryover injury from fomesafen (Flexstar, Prefix, Reflex, Intimidator, Marvel, Dawn, Rhythm, etc.) is starting to show in a few corn fields.  This is because some  applications in late June and July in 2023 coupled with a very dry fall allowed the herbicide to persist into winter.  Recent rains then allow any herbicide carryover to more completely get into the soil solution.

Fomesafen carryover injury in corn and grain sorghum looks similar.  Expect to see stunting and interveinal chlorosis as pictures below sent from crop consultants clearly shows.

Striping of corn leaf veins characteristic of fomesafen carryover

In some cases, particularly on ends of fields where herbicide overlap more often occurs, the injury is more substantial with some leaves showing burn.  This burning will be particularly apparent in grain sorghum as it is 4 times more susceptible to fomesafen carryover than corn.

There has been just a hand full of reports, but more folks may see symptoms as they evaluate their fields over the next week or so. The last time we had a significant number of fomesafen carryover reports was 2013 and 2015.

The set up was similar with later planting of soybeans in the previous year.  Pigweed was the target then as well with a lot of fomesafen products being applied in late June and into July. We had dry falls in 2012 and 2014 which helped make the fomesafen more persistent.

Fortunately, most of the corn suffering from fomesafen carryover in both those springs shook it off after about 10 days and went on to make a good crop.  I would expect a similar outcome this spring with corn that is showing the stunted/yellowing symptoms now.

The grain sorghum may very well be a different story.  Grain sorghum fields with fomesafen carryover will emerge fine but once they get into the light they may “go backwards”.  With grain sorghum it can be hard to tell what the cause is as grain sorghum seedlings have a sundry of issues that will make them go backwards like atrazine injury, greenbug injury, etc. but if the veins show the “striping” as seen above, fomesafen is likely at least part of the problem.

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