Fomesafen Injury on Corn
Fomesafen injury to corn is very distinct and will result in midrib and subvein clearing, which appears as a “stripping” of the leaves. The tissue between the veins will not yellow; this is symptomatic of nutritional deficiencies. Improper unfurling to a “buggy whipping” of the leaves may result from more severe fomesafen injury. The midrib can also be weakened and collapsed.
Fomesafen, the active ingredient in Flexstar and Reflex, is often used for postemergence control of late emerging broadleaf weeds in soybean, dry bean and snap been. Fomesafen carries a 10-month rotation restriction to both seed and field corn. Late applications of fomesafen followed by fairly early corn planting the next season can result in nearing this restriction. Studies have shown that fomesafen is broken down in the soil more quickly under anaerobic (oxygen deficient) conditions. Anaerobic conditions result after a rainfall event in which water infiltration forces out oxygen in the pore spaces of the soil. In a season of drought or low precipitation, fomesafen may not be fully degraded and has the potential to carryover in sandy or even very well-drained soils. Corn injury may be first noticed on sandy hills and knolls because these areas can only hold moisture for a short period of time.