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Multiple-Pathogen Inoculation of Cucumber (Cucumis sativus) Seedlings. A. J. Wyszogrodzka, Postdoctoral Research Associate, ARCO Plant Cell Research Institute, 6560 Trinity Court, Dublin, CA 94568. P. H. Williams, and C. E. Peterson. Professor, Department of Plant Pathology, University of Wisconsin-Madison, 1630 Linden Drive, and Professor, USDA-ARS, Department of Horticulture, University of Wisconsin-Madison, 1575 Linden Drive, Madison 53706. Plant Dis. 71:275-280. Accepted for publication 5 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0275.

Methods were developed for simultaneous inoculation of cucumber seedlings with Pseudomonas syringae pv. lachrymans (P. s. pv. lachrymans), Pseudoperonospora cubensis, Colletotrichum orbiculare race 1, and Cladosporium cucumerinum and for sequential inoculation with Corynespora cassiicola under controlled environments. Localized inoculation of selected sites on 2-day postemergent cotyledons with P. s. pv. lachrymans (2.2 104 colony-forming units delivered in 1 l of phosphate buffer into a toothpick wound), with P. cubensis (50 zoospores in 1 l of water), with Colletotrichum orbiculare (200 spores in 5 l of water), and with Cladosporium cucumerinum (2,000 spores in 10 l of water delivered on the apical growing point), followed by 48 hr of incubation at 20 C, 100% relative humidity (RH) in the dark and 24 hr in a 20 C lighted growth chamber, permitted differentiation between resistant and susceptible cucumber cultivars GY 14, Wisconsin SMR 18, GY 3, and Straight 8. No induced resistance was observed when seedlings of GY 14 were inoculated with Corynespora cassiicola (1,000 spores in 5 l of water followed by 48 hr of incubation at 24 C, 100% RH in the dark) 72 hr after inoculation with the above pathogens.

Keyword(s): angular leaf spot, cucumber anthracnose, cucumber scab, disease resistance, downy mildew, multiple-disease resistance, target leaf spot.