INFLUENCE OF ROOT PATHOGENIC ACTINOMYCETES ON THE TRIMMING OF THE ROOTLETS OF SOME SPECIES OF ROSACEAE WITH ROOT HAIRS

Root pathogenic actinomycetes are considered to be the cause of the specific replant disease in some species of Rosaceae as they invade the cortex of rootlets by penetrating the epidermal cells.
They damage the cortex cells in such a way that the cortex tissue and finally the rootlets die off.
The infection takes place in young and healthy rootlets, which possess intact root hairs.
Detailed investigation showed that the actinomycetes enshroud and penetrate the root hairs and cause their collapse.
By using data of some earlier experiments, the correlation between the trimming of rootlets with root hairs and the presence of actinomycetes in the rootlets was detected.
It was also found that the trimming of rootlets with root hairs clearly decreased with increasing infection of the rootlets by actinomycetes.
Similar results were not obtained with the endotrophic mycorrhiza and with endophytic nematodes.
Therefore, it may be concluded that the root pathogenic actinomycetes reduce the efficiency of the rootlet systems by damaging the root hairs.

IV International Symposium on Replant Problems

G. Otto, H. Winkler

https://doi.org/10.17660/ActaHortic.1998.477.5