Peanuts – Patch of Dead Peanuts, CV Pictures

More than one way to skin a cat, more than one reason a patch of peanuts can be dead in a field. Drowned in a bottom, struck by lightning, killed by disease, terminated by herbicide, and other woes… Zinc toxicity can also be fatally toxic. Aside from a soil test report indicating elevated levels, visual symptoms of zinc toxicity include small dead brown plants where levels are highest, and in areas less toxic the peanuts can start to grow but begin to show split stems either near the crown or higher up above the ground with poorly developed root systems. Pictures from two different fields are attached. Peanut pictures 7-14-21 The only thing to do in these cases is to make a note going forward. Zn toxicity is common on old building sites, where galvanized roofs once were, or where heavy poultry litter applications have been used or where fertilizer with metal filings was applied. If the field has been planted to peanut before, and this is the first time toxicity symptoms are showing up, the reason for this can be a little more difficult to pinpoint. Sometimes, if the zinc levels are marginally toxic for the pH, some liming prior to planting can be used to raise the pH and decrease its availability, but there is a limit to how much we can do.

Soil with:

Zn 6 to 10 lb/A can be limed to 6.2 pH

Zn 11 to 20 lb/A can be limed to 6.4 pH

Zn 21 to 30 lb/A can be limed to 6.5 pH

Zn over 30 not recommended.

Cylindrocladium black rot can also cause the taproot to appear split, but in those cases, the splitting is less superficial and more severe and black, allowing the taproot to be wiggled apart following its loss of structural integrity.