The Resistance of Mango (Mangifera indica) Cultivars to Tip Dieback Disease in Florida.

The resistance of Mangifera indica to tip dieback disease caused by Botryosphaeria ribis, anamorphic state Fusicoccum sp., was determined on 361 trees of 122 mango cultivars and relatives planted in the mango germ plasm collection at the University of Florida, Tropical Research and Education Center, Homestead. Three trees from each cultivar were evaluated on a 1 to 5 scale ranging from those free of tip dieback to those with extensive branch necrosis. Each cultivar was assigned to one of eight major systematic groups based on race or geographic origin. Resistance to tip dieback disease was not associated with any of the groups. No significant differences in mean disease severity were found among the Indian, Southeast Asian, West Indian, Haden, or Sandersha parts of the Haden-Sandersha Complex, Turpentine types, or a group of unclassified cultivars. Two Mangifera species (M. odorata and M. zeylanica) showed the lowest mean disease rating. Cultivars were also grouped into monoembryonic and polyembryonic types. Although several mango cultivars, mainly found in the monoembryonic group, appeared to be free of the disease, resistance to tip dieback was not associated with embryony. This study provides the first indication that field resistance to tip dieback may be present in some mango cultivars.