Use of Filtration for Removal of Conidia of Penicillium expansum from Water in Pome Fruit Packinghouses. R. A. Spotts, Mid-Columbia Agricultural Research and Extension Center, Oregon State University, Hood River 97031. L. A. Cervantes, Mid-Columbia Agricultural Research and Extension Center, Oregon State University, Hood River 97031. Plant Dis. 77:828-830. Accepted for publication 26 April 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0828.

Removal of conidia of Penicillium expansum from aqueous suspensions with sieves of 2.0 mm to 10 μm and with a triple-stage cartridge filter unit with 5-, 1-, and 0.45-μm terminal filters was studied. The effectiveness of sand filters and cartridge filters for removal of conidia also was evaluated in commercial apple drenchers and packinghouse flumes. The sieves were effective for removal of conidia only when 5–20 mg/ml of soil was added to the suspension, indicating that conidia frequently were bound onto soil particles. In the packinghouse, sand filters did not reduce the concentration of P. expansum in the flume water. A triple-stage filter unit with a 0.45-μm terminal cartridge filter removed 99% of P. expansum conidia from aqueous suspensions in the laboratory, and a similar four-element cartridge unit removed 92% of P. expansum conidia from the carrier water suspension used in commercial drenchers. The filter systems were advantageous for prolonging the use of drencher suspensions and water in packinghouses but currently lack the capacity to provide continuous, unaided reduction of concentrations of conidia to levels that would control blue mold.

Keyword(s): decay, postharvest.