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Citrus Leaf Pieces as Traps for Phytophthora parasitica from Soil Slurries. G. R. Grimm, Plant Pathologist, ARS, USDA, Orlando, Florida 32803; Ann F. Alexander, Biological Laboratory Technician, ARS, USDA, Orlando, Florida 32803. Phytopathology 63:540-541. DOI: 10.1094/Phyto-63-540.

Phytophthora parasitica readily infected citrus leaf pieces floating on a soil slurry. Numerous sporangia were produced along the cut edges of floating leaf pieces in 3 to 4 days at room temperature, but were absent from whole leaves or cut pieces that sank. Abundant sporangia were produced on leaf pieces of all citrus varieties, but only a few were produced on leaf pieces from other plants. Pure cultures of P. parasitica isolated from citrus and noncitrus leaf pieces were pathogenic to citrus seedlings. Citrus leaf pieces and calamondin (Citrus reticulata var. austera ? X Fortunella sp. ?) fruits were equally effective as traps for P. parasitica.