Reaction of some weeds to Verticillium albo-atrum.
The reaction of 38 weed species to a pathogenic isolate of V. albo-atrum from okra (Hibiscus esculentus) was studied in glasshouse experiments. Solanum spp. and most Malvaceae, except Malva parviflora, proved highly susceptible and showed typical symptoms of Verticillium wilt, as did Acanthospermum hispidum and Portulaca oleracea. Some weeds harboured V. albo-atrum without showing any external symptoms of disease. It is concluded that V. albo-atrum can survive for long periods in weeds, throughout the crop rotations.