Toxicity of the Surfactant Nacconol to Four Decay-Causing Fungi of Fresh-Market Tomatoes

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Abstract
The anionic surfactant Nacconol 90F (active ingredient sodium dodecylbenzene sulfonate) was fungistatic in vitro to mycelia and spores of 4 decay-causing fungi of California [USA] tomato fruit. ED50 values for Botrytis cinerea, Geotrichum candidum, Phytophthora parasitica and Rhizopus stolonifer were 23, 20, 75 and 27 .mu.g a.i.[active ingredient]/ml for mycelial growth and 116, 60, 60 and 136 .mu.g a.i./ml for spore germination, respectively. Nacconol was fungicidal to B. cinerea spores at concentrations greater than 5000 .mu.g a.i./ml. In laboratory tests, B. cinerea decay of injured fresh-market tomatoes was significantly reduced by treating the fruit in Nacconol solutions of 200, 2000 or 5000 .mu.g a.i./ml for 3 min at 38.degree. C followed by a fresh-water rinse. Nacconol amendments of 200, 2000 or 5000 .mu.g/ml did not enhance the ability of 100- or 400-.mu.g/ml chlorine solutions to reduce the incidence of B. cinerea decay. When the water rinse was omitted, Nacconol amendments significantly improved the efficacy of 100-.mu.g/ml but not 400-.mu.g/ml chlorine treatments. Phytotoxicity symptoms developed when fruit were not rinsed after treatment with 2000 or 5000 .mu.g/ml Nacconol alone or in combination with chlorine.