Reduction of Pratylenchus penetrans in potato tubers treated with oxamyl and sodium hypochlorite

Soaking potato (Solanum tuberosum 'Russet Burbank') tuber halves for 1 h in sodium hypochlorite (1% available chlorine) or for 20 min in a 32 mg mL−1 solution of oxamyl (24% liquid) reduced the number of root-lesion nematodes (Pratylenchus penetrans) in the peel by 92 and 88%, respectively, relative to untreated tuber halves extracted in a mist chamber for 2 wk. Treated tuber halves were grown in pots for 8 wk in the greenhouse. There was no phytotoxicity in the plants that emerged although sodium hypochlorite may have inhibited plant emergence; both treatments reduced the number of days required for plant emergence by 3–6 d. In general, both chemicals increased plant growth. Oxamyl was completely effective in preventing a nematode infestation of the soil; sodium hypochlorite was ineffective. On average, only a single specimen of P. penetrans was recovered from the oxamyl-treated root system vs. 835 in the sodium hypochlorite treatment. No P. penetrans was recovered from the oxamyl-treated original seed-piece after 8 wk whereas an average of 427 and 329 half-tuber−1 were present in those treated with water or sodium hypochlorite, respectively. The data suggest that a 20-min immersion of P. penetrans-infested potato seed pieces in oxamyl is extremely effective in preventing soil infestation by the nematode. Key words: Bleach, disinfection, potato, Pratylenchus penetrans, root-lesion nematode, Solanum tuberosum