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Determination of Host Resistance to Beetle Transmission of Plant Viruses. R. C. Gergerich, Department of Plant Pathology, University of Arkansas, Fayetteville 72701; H. A. Scott, and S. L. Wickizer. Department of Plant Pathology, University of Arkansas, Fayetteville 72701. Phytopathology 81:1326-1329. Accepted for publication 3 June 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-1326.

Two comoviruses, cowpea mosaic virus (CPMV) and cowpea severe mosaic virus (CPSMV), were easily mechanically transmissible to Vigna unguiculata subsp. unguiculata ‘Monarch’ cowpea and Phaseolus vulgaris L. ‘Black Valentine’ bean. Leaf-feeding beetles, however, rarely transmitted either virus to bean, while they transmitted both viruses more frequently to cowpea. When the gross-wound inoculation technique, which mimics beetle feeding, was used to inoculate bean and cowpea with purified CPMV and CPSMV mixed with beetle regurgitant or pancreatic ribonuclease, the results were similar to those observed in beetle transmission tests. Monarch cowpea was more susceptible to mechanical inoculation with diluted infectious sap from CPMV- or CPSMV-infected plants than was Black Valentine bean. Four cultivars of cowpea with different susceptibilities under field conditions to the cowpea strain of southern bean mosaic virus showed a similar pattern of susceptibility when inoculated with the gross-wounding technique.

Additional keywords: screening for resistance.