Efficacy of chlorine dioxide for disease control on stored potatoes

Olsen, Nora L.; Kleinkopf, Gale E.; Woodell, Lynn K.

Efficacy of chlorine dioxide for disease control on stored potatoes

2003

Olsen, Nora L. | Kleinkopf, Gale E. | Woodell, Lynn K.

The post-harvest application of chlorine dioxide (CIO2) was evaluated as a disease suppressant for stored potatoes. Chlorine dioxide was prepared by acidifying a buffered sodium chlorite solution with a food grade acid. In vitro studies verified the effectiveness of CIO2 at low concentrations (ED50 = 2 to 122 ppm) against Erwinia carotovora (soft rot), Fusarium spp. (dry rot) and Helminthosporium solani (silver scurf). Evaluations of tubers inoculated with Phytophthora infestans (late blight) and Fusarium spp. or infected with H. solani and then treated with CIO2 either going into storage or through the humidification system resulted in a lack of disease suppression. Inconsistent performance of CIO2 in storage appeared to be a result of several contributing factors. Chlorine dioxide concentrations varied greatly (up to six-fold), depending upon the method of activating and diluting sodium chlorite solutions. Chlorine dioxide is a gas soluble in water and, therefore, is easily released from solution (25%-75% loss) into the air when applied as an aqueous spray. Chlorine dioxide reacts quickly with the tuber and associated organic matter, thereby reducing the effectiveness. Applying higher than currently registered rates may be necessary to achieve measurable disease suppression.

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