Disease Note.

First Report of Penicillium Stem Rot Caused by Penicillium oxalicum on Long English Cucumber in British Columbia Greenhouses. J. G. Menzies, Pacific Agriculture Research Centre Agriculture and Agri-Food Canada, P.O. Box 1000, Agassiz, B.C. Canada, V0M 1A0 . C. Koch, Pacific Agriculture Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1000, Agassiz, B.C. Canada, V0M 1A0, J. Elmhirst, B.C.M.A.F.F., Cloverdale, B.C., Canada, V3S 4P9, and J. D. Portree, B.C.M.A.F.F., Abbotsford, B.C., Canada, V2S IK2. Plant Dis. 79:538. Accepted for publication 7 April 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0538D.

In July 1994, a commercial greenhouse grower of long English cucumber (Cucumis sativus L.) cv. Europa in Richmond, B.C., Canada, reported severe problems with stem lesions caused by Botrytis cinerea Pers.:Fr. and wilt caused by Fusarium oxysporum f. sp. cucurbitacearum Gerlagh & Blok. Upon examining and confirming these diseases, we found that 10 of the plants suffered from what appeared to be Penicillium stem rot. Symptoms included dry, pale brown lesions extending up and down from stem nodes, with profuse bluish-gray sporulation of Penicillium spp. On some plants, lesions had girdled the stem, causing stem collapse above the lesion. Pieces of infected stem were sampled, surface sterilized for 5 min in 0.5% NaOCI, and plated onto dishes containing acidified potato-dextrose agar. Penicillium spp. were isolated from all infected stem pieces and all isolates identified as Penicillium oxalicum Currie & Thorn, the causal agent of Penicillium stem rot (1). Koch’s postulates were completed after inoculating stems of cucumber cv. Corona by brushing dry spores of P. oxalicum onto wounded petioles (1), thus confirming the pathogenicity of the isolates.