The role of Thielaviopsis basicola in the specific replant disorders of cherry and plum

The hypothesis that Thielaviopsis basicola might be the causal agent of the specific replant disorders of cherry and plum was tested in experiments with pot-grown trees and by observations on the distribution of the pathogen. The results obtained with certain strains of T. basicola simulated and were consistent with all features known to characterize the specific replant disorders, viz. inter- and intra-generic specificity of effect; host symptoms; establishment, immobility and persistence of the causal agent in soil; normal growth of affected trees after transfer to ‘non-replant’ soil; limited influence of soil type on the incidence of the disorder. T. basicola was therefore considered to be the probable causal agent of the specific replant diseases of certain Prunus species. The etiology of these diseases is discussed. T. basicola was neither pathogenic to apple nor associated with the growth of apple. The apparently closely similar specific replant disorder of Malus is therefore considered to be causally distinct from those of cherry and plum.