Survival of Xiphinema Index and Reservoirs of Fanleaf Virus in Fallowed Vineyard Soil

An experiment to control fanleaf virus of grapevines by fallow-rotation was established in California in November 1959. The infected grapevines were excised 45 cm below the surface of the soil. Roots of these old vines were recovered at intervals up to 4.5 years after the plants were removed. New growth from recovered root pieces yielded fanleaf virus. The nematode vector, Xiphinema index, also persisted in the fallow soil diminishing in numbers in correlation with the depletion of surviving roots. The decay of host plant roots may eliminate the virus reservoir and for control of the virus in future plantings a minimum of at least 5 years rotation is indicated.