Chlorine concentration and the inoculation of tomato fruit in packinghousedump tanks

Chlorine concentrations (pH 6 to 7 and 22 to 27 degreesC) that killed arthr ospores (spores) of Geotrichum candidum or sporangioles (spores) of Rhizopu s stolonifer, causal agents of sour rot and Rhizopus rot, respectively, in moving water within 30 to 45 s did not prevent these pathogens from inocula ting wounded tomatoes (Lycopersicon esculentum) in a water flume containing chlorine and spores. Free chlorine concentrations of 20 or 25 mg/liter wer e lethal to spores of G. candidum within 30 s in most in vitro tests, where as spores of R. stolonifer were slightly less sensitive. Wounded tomatoes p laced in a flume with free chlorine at 30 mg/liter and then exposed to spor es for 1 min developed about 50% less decay incidence during storage at 24 degreesC for 6 days than did fruit exposed to spores and water alone. In th e absence of chlorine, incidence averaged 57% (range, 15 to 95%) for R. sto lonifer and 38% (range, 17 to 58%) for G. candidum. Sporadic sour rot lesio ns were observed among fruit that had been treated with free chlorine at 75 mg/liter, whereas chlorine at up to 180 mg/liter failed to completely prot ect fruit from Rhizopus rot. A water-soluble dye rapidly penetrated wounds on tomato fruit. The dye framed the outlines of cells at the wound surface and appeared to penetrate into a few intercellular spaces, Application of 1 % sodium hypochlorite decolorized the dye on the wound surface, whereas dep osits located below the wound surface remained blue. Thus, spores suspended in moving water can escape the action of chlorine if carried into intercel lular spaces by diffusion or by capillary movement of cell sap and water.