Reaction of broccoli to isolates of Verticillium dahliae from various hosts

Isolates of Verticillium dahliae from 15 different hosts and V. albo-atrum from alfalfa were tested for their ability to cause wilt on broccoli using a root-dip inoculation method. None of the isolates caused vascular discolo ration in broccoli except those from cabbage and cauliflower that were weak ly pathogenic. Broccoli cultivars Baccus, Greenbelt, Parasol, Patriot, and Symphony showed resistance to Verticillium infection. Re-isolated strains f rom fresh samples of internally discolored broccoli and cauliflower root ti ssues were unable to cause disease symptoms on re-inoculation of broccoli, but caused severe disease on cauliflower. Inoculation of 5-, 7-, 9-, or 11- week-old plants did not alter the resistance in broccoli or the susceptibil ity in cauliflower against Verticillium. Immunity of broccoli against infec tion by isolates of V. dahliae from non-crucifer hosts, its resistance agai nst crucifer isolates, and as previously described, attrition of V. dahliae microsclerotia in soil by broccoli residue, coupled with its importance as a commercial vegetable, make broccoli an attractive rotation crop for the management of Verticillium wilt in many cropping systems.