THE RESISTANCE OF MANGO (MANGIFERA-INDICA) CULTIVARS TO TIP DIEBACK DISEASE IN FLORIDA

The resistance of Mangifera indica to tip dieback disease caused by Bo tryosphaeria ribis, anamorphic state Fusicoccum sp., was determined on 361 trees of 122 mango cultivars and relatives planted in the mango g erm plasm collection at the University of Florida, Tropical Research a nd Education Center, Homestead. Three trees from each cultivar were ev aluated on a 1 to 5 scale ranging from those free of tip dieback to th ose with extensive branch necrosis. Each cultivar was assigned to one of eight major systematic groups based on race or geographic origin. R esistance to tip dieback disease was not associated with any of the gr oups. No significant differences in mean disease severity were found a mong the Indian, Southeast Asian, West Indian, Haden, or Sandersha par ts of the Haden-Sandersha Complex, Turpentine types, or a group of unc lassified cultivars. Two Mangifera species (M. odorata and M. zeylanic a) showed the lowest mean disease rating. Cultivars were also grouped into monoembryonic and polyembryonic types. Although several mango cul tivars, mainly found in the monoembryonic group, appeared to be free o f the disease, resistance to tip dieback was not associated with embry ony. This study provides the first indication that field resistance to tip dieback may be present in some mango cultivars.