Effect of a Surfactant on Control of Decay of Anjou Pear with Several Fungicides. R. A. Spotts, Associate Professor, Oregon State University, Mid-Columbia Experiment Station, Hood River 97031. . Plant Dis. 68:860-862. Accepted for publication 18 June 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-860.

Wounded pear fruits (cultivar Anjou) were immersed for 5 min in 0.35% sodium ortho phenylphenate tetrahydrate (SOPP), 0.35% SOPP plus 0.5% Ortho X-77, or water at 2, 10, and 20 C. Each solution contained 1, 2, or 10 × 10³ conidia per milliliter of Penicillium expansum, Botrytis cinerea, or Mucor piriformis, respectively. SOPP reduced decay caused by B. cinerea but not that caused by M. piriformis or P. expansum. Addition of Ortho X-77 to SOPP increased decay caused by all fungi. Solution temperature did not affect decay. Addition of Ortho X-77 to captan or iprodione increased decay caused by P. expansum, and addition of Ortho X-77 to captan or etaconazole increased decay caused by B. cinerea. Addition of Ortho X-77 to captan also increased decay caused by M. piriformis. In two packinghouses, treatment of wound-inoculated pear fruit with a commercial detergent containing SOPP before inoculation resulted in increased incidence of decay. Addition of Ortho X-77 at 0.1, 0.3, and 0.5% a.i. to 1,500 ppm a.i. of captan increased the incidence of decay and decreased captan residue on the fruit as measured with bioassay. Addition of Ortho X-77 to benomyl also reduced fungicide residue on the fruit. SOPP treatments did not reduce fungal spore germination and appeared to stimulate germ tube growth of M. piriformis.

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