Epidemiology, ecology and management of rhizogenic agrobacteria, causative agents of hairy root disease in vegetable crops.

Crazy roots, a disease caused by Agrobacterium rhizogenes, is becoming a major problem in the Flemish greenhouse horticulture, in particular in the cultivation of tomato, cucumber and eggplant.A.rhizogenes infection results in an extensive development of the root system and in a strong vegetative growth of the plant, which is detrimental for fruit development. During the last few years crazy roots has spread fast in the Flemish horticulture, causing considerable economical losses. Moreover, once a greenhouse is infected, disinfection treatments are not effective, probably because A. rhizogenes can reside in the biofilm of the irrigation piping system, where it is protected against disinfectants. In a first part of this doctoral research, the prevalence of A. rhizogenes in the Flemish greenhouse horticulture will be examined. For this, molecular tools are developed and used for genetic fingerprinting of the isolated A. rhizogenes strains. This enables to examine the spread ofdifferent genotypes, and possibly correlate the genotype with the aggressiveness of the particular strains. In a second part, the prevention and treatment of A. rhizogenes biofilms is examined. Several disinfection treatments that are currently widely used in horticulture are evaluated for their efficacy to treat A. rhizogenes biofilms.(URL:null)