Posted 9/14/2021 14:34 (#9220060) Subject: Tar Spot
Email I received RJ Obrien-
As it pertains to agronomy, we adopt Uncle Harold’s wise teaching “I’m smart enough to know that I’m dumb enough not to know” approach.
Early corn harvest across N IL, WC IL, C IL and EC IL show lighter than expected test weight: most reports 54 LB v typical 58+ LB/BU measurements. This is a surprise.
A fungus known as “tar spot” has livened up the discussion as perhaps one explanation for below expected early corn yields and lighter than normal test weight across northern half of IL.
“Tar spot” premature kills the corn stalk, which inhibits proper seed fill. Hence the lower test weight results and lower than expected yield results. Premature stalk death makes the corn plant more susceptible to wind damage. Farmers will hustle to combine it.
One N IL farmer tested the thesis on single fungicide application v double fungicide application to control “tar spot” – hand shelled test 20-25 BPA yield difference in the same field. Via shared snaps, ear girth is substantially smaller for corn inflicted with “tar spot” than without it. Contacts believe 90-95% of farmers practice single fungicide application to corn fields.
Presence of “tar spot” believed most concentrated from N IL, S WI, N IN and S MI. However, it has been detected in NE Iowa, too. We field no such observations across S IL, S IN.
Again. We normally leave agronomy to the agronomists. But given the lopsided production shift of 2021/22 US corn crop from US WCB to the US ECB – the market cannot tolerate corn production losses below expectations in the US ECB.
If “tar spot” is a legitimate concern and drag on 2021/22 US ECB corn yield, it should become more visible on the USDA Oct 12, 2021, production report.