Potato Seed Piece Treatments for Controlling Rhizoctonia solani Infections

Abstract

Rhizoctonia solani infection of potato causes seed piece decay and stem and tuber lesions, resulting in delayed emergence and uneven stands, low-vigor plants and unmarketable tubers. Rhizoctonia prevention effectiveness of three fungicide/fir bark dusts and nontreated tubers were compared on three varieties. Seedpieces of Viking, Atlantic and Norkotah 278 were treated and planted in separate commercial fields. A randomized complete-block design with four replications with four 26-foot rows per treatment plot included four treatments: 0.5 lb Maxim, 1.0 lb Tops MZ, and 1.5 lb Nubark Captan dust/100 lb seed. Plant stems, stolons and tubers were examined for Rhizoctonia infection at the tuber initiation stage and tubers were examined again at mature stage. Maxim and Tops MZ reduced stolon infection in Atlantic and Norkotah 278 and reduced stem infection in Norkotah 278. Plants from Maxim treated tubers produced more stems/plant in Norkotah 278 and produced more weight of tubers weighing less than four oz in all three varieties. Differences in seed tuber conditioning and mechanical damage in seed handling increase variability of treatment effects. Repeated testing of potato seed piece treatments in Texas High Plains conditions is the best way to confirm potential of beneficial effects of seed treatment.