METHOD: Both CFU counts and Visual Examination CONDITIONS: Green House - 16h light 18-22C METHOD NARR: Tubers were planted in the GH and inoculated with V. albo-atrum 4 weeks after planting. Root injury was accomplished by removthe root ball and inoculation by submerging the remaining portion of the root ball for 10 min. in spore suspension. Visual examination started 4 weeks after inoculation and continued weekly for 4 weeks. Vascular colonizatiosed by counting total CFU in 0.1ml aliquot of plant sap in those genotypes where visual assessment showed resistance or tolerance. RESULTS NARR: No wilt symptoms were observed in resistant plants while susceptible plants expeorosis, necrosis and death. Extensive stem colonization by the pathogen occured in most of the plants rated resistant. AUTHOR EXPLANATION: Results indicate that tolerance is more common than resistance. Tolerance is defined as noh significant stem invasion. Resistance is defined as no symptoms and very low stem invasion. Visual symptom expression and degree of stem invasion by V. dahliae are poorly correlated.