Abiotic transmission of southern bean mosaic virus in soil

When soil in pots was infested with southern bean mosaic virus (SBMV), it became infective for highly susceptible Phaseolus vulgaris bait plants. Soil could be infested by adding either infected plant tops or roots or by growing infected plants in it. Release of SBMV by roots of P. vulgaris cv. Red Kidney reached a maximum at flowering and thereafter declined, but some virus was still recovered in drainage water when the plants were dead. When grown in infested soil P. vulgaris cv. Bountiful was more susceptible to infection at 26 C than at 21 or 32 C, temperatures which were less favourable for plant growth. The addition to virus-infested soil of tomato roots carrying nematodes (Meloidogyne sp.), fungi and other soil biota did not increase virus infection in bait plants. It is concluded that SBMV resembles tobacco mosaic virus in being able to infect plant roots abiotically in infested soil.