Viruses infecting cucurbits in Queensland

Abstract

Three viruses infecting cucurbits were investigated. The most common was watermelon mosaic virus (WMV), which resembled WMV type 2. Complete infection of pumpkin (Cucurbita maxima) and squash (C. pepo) crops by this virus often occurred. Transmission by four common aphid species was demonstrated and the host range for systemic infection was found to extend into four plant families. The long, flexuous rod particles measured approximately 760 mµ. Cucumber mosaic virus (CMV) was comparatively rare, but the isolates obtained resembled QCMV in host reactions and serological tests. Squash mosaic virus (SMV) was present in about 6% of the specimens examined. An antiserum prepared from a Queensland isolate reacted similarly in gel-diffusion tests to one prepared at Davis, California. Most symptoms produced by SMV were rather mild. Persistent type transmission by an unreported vector, the 28-spotted ladybird (Henosepilachna vigintioctopunctata (F.), was demonstrated, and the particle size shown to be approximately 30 mµ. in diameter.