Susceptibility of Some Stone and Pome Fruit Rootstocks to Crown Gall

Abstract

The susceptibility of different fruit rootstocks to crown gall disease was investigated in greenhouse and
field experiments with numerous strains of Agrobacterium tumefaciens over three years. Plants were inoculated in
the roots and shoots for pot experiments. Field experiments were performed in a naturally contaminated nursery
plot. The genotypes Prunus dulcis and P. persica showed a high level of susceptibility to A. tumefaciens. Among the
stone rootstocks, bitter almond was highly susceptible in all experiments. Apricot and Cadaman rootstocks displayed
low susceptibility but larger galls, showing that there was no relation between rootstock susceptibility and gall size.
Among pome rootstocks, quince BA29 was resistant to the disease, while MM106 was susceptible in potted trials;
however, in the field essays, pome rootstocks did not become galled, possibly because the strains had selected for and
adapted to stone rootstocks.