Effect of chlorine atmospheres on sprouting and development of dry rot, soft rot and silver scurf on potato tubers

The effect of chlorine atmospheres on sprouting and development of potato (Solanum tuberosum L.) dry rot, soft rot and silver scurf were evaluated. Potato tubers were inoculated with Fusarium sambucinum, Erwinia carotovora subsp. atroseptica or Helminthosporium solani, and placed in hermetic chambers at 15degreesC containing 0 (control), 2, 20 and 201 mg/l of available chlorine in moist air. After 10 days (dry rot and soft rot) or 40 days (silver scurf) of exposure to chlorine. severity of each disease was evaluated. The results showed that pathogens displayed differences in their susceptibility to chlorine. H. solani, a surface pathogen, was more sensitive than wound-borne pathogens F sambucinum and E. carotovora subsp. atroseptica. Exposure to 2 mg/l of chlorine in moist air for 40 days markedly reduced silver scurf, whereas chlorine significantly reduced dry rot and soft rot only upon exposure to higher chlorine concentration of 201 mg/l for 10 days. A 2-day exposure to 20 mg/l was found effective in controlling silver scurf. Continuous exposure to chlorine for 40 days was shown to significantly reduce sprouting of the tubers at concentrations of 20 and 201 mg/l in moist air. (C) 2002 Elsevier Science B.V. All rights reserved.