Cadre (active ingredient= imazapic) is an ALS-inhibiting herbicide registered for use in peanut. The persistence of the herbicide, which has an average half-life of 120 days, requires growers pay particular attention to the herbicide’s rotational restrictions. Fortunately, Cadre carryover injury to sweetpotato has been rare in 2013. I recently found one field in Chickasaw County with sweetpotato plants exhibiting Cadre carryover symptoms. This post is intended as a reference for growers who suspect Cadre carryover. However, Cadre carryover symptoms in sweetpotato are very similar to numerous other biotic and abiotic diseases and/or disorders.
Sweetpotato plants affected by Cadre carryover will appear stunted. Older growth is often chlorotic. Newer growth is red with shortened internodes and stunted leaves. Injury symptoms will often be more severe at the end of a row where the applicator slowed and applied a higher rate or where applications were overlapping. Symptoms may also be more severe in portions of a field with higher soil pH, decreased clay content, or decreased organic matter content. For sweetpotato, the herbicide label currently dictates a 26 month rotational restriction following Cadre application. For more information on specific rotational restrictions for other crops, please see the product label.