Disease Note.

Blackeye Cowpea Mosaic Potyvirus (BICMV) on Yard-long Bean in the Mariana Islands. G. C. Wall, CALS/AES, University of Guam. C. A. Kimmons, CALS/AES, University of Guam. Plant Dis. 80:224. Accepted for publication 5 January 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0224G.

A mosaic disease of Vigna unguiculata (L) Walp. subsp, sesquipedalis (L.) Verde, common on Guam and Saipan, was shown to be caused by the blackeye cowpea mosaic potyvirus (BICMV) via ring interface. Protein A sandwich-enzyme-linked immunosorbent assay (PAS-ELISA), and host range studies. The local BICMV isolate induced mottle on V. unguiculata cv. California Blackeye and vein-banding symptoms on Nicotiana benthamiana; no downward cupping of leaves was observed on these hosts. Ring interface tests included antisera for BICMV, cowpea chlorotic mottle virus (CCMV), cowpea severe mosaic virus (CSMV), southern bean mosaic virus cowpea strain (SBMV-CP), and tobacco mosaic virus (TMV) legume strain. ELISAs included antisera and antigens for BICMV-W, bean common mosaic virus (BCMV), and watermelon mosaic virus 2 (WMV2), plus antiserum for BICMV. Test samples gave positive results only with antisera for BICMV-W and BICMV (obtained from L. Bos, Research Institute for Plant Protection, Wageningen, The Netherlands, and C. W. Kuhn, University of Georgia, respectively). Sap inoculation onto 1-week-old seedlings of cvs. Local Red and Burpee asparagus bean reproduced the symptoms observed in the field. Nonper-sistent aphid transmission was demonstrated with apterous Aphis craccivora. Seed transmission was detected when seed from infected plants was grown in cages. Symptoms developed on the first true leaf in 37% of emerging seedlings and BICMV was confirmed by ELISA.