THE EFFECT OF THE 2004 HURRICANES ON CITRUS FLOWERING POTENTIAL FOR THE 2005 SEASON

James J. Salvatore

Abstract


Up to 3 hurricanes (Charley, Frances, and Jeanne) passed over the same citrus areas of Florida in August and September 2004. The Indian River (IR) citrus area experienced two hurricanes, lower West Coast areas experienced one, and Central Florida citrus areas had all three hurricanes pass over. On a percentage basis, relatively few trees were permanently damaged, but many trees in the higher wind locations lost some fruiting wood and had extensive leaf loss. Cohorts of fall growth flushes occurred after each hurricane in proportion to the leaf loss which ranged from negligible to 90% defoliation. After the 2004 hurricanes, one block of 'Murcott' tangerine (Citrus reticulata × C. sinensis), two blocks of 'Flame' grapefruit (C. paradisi) and one block of 'Marsh' grapefruit, for which yields were measured the previous year, were selected for subsequent evaluation of hurricane recovery. In trees from blocks with no natural windbreaks, outer trees on the windward side were more defoliated (~60%) than interior trees (~30%), and the sides of trees facing into the wind were more defoliated (~55%) than their leeward sides (~30%). The lower areas of the tree canopies experienced less defoliation (~35%) than the middle to upper sections (~60%). There was also significantly more defoliation from the spring 2004 flush, compared to the more recent summer 2004 flush. Some of the earliest new flush following the first hurricanes was damaged by subsequent hurricanes. On trees that had heavy leaf loss, fall flushes were yellow and appeared weak. Data from previous studies suggested that flushes after hurricanes Charley and Frances likely would mature sufficiently to allow their buds to be induced to flower, but we hypothesized that buds on flush after hurricane Jeanne likely would not be mature enough by wintertime conditions for flower bud induction. Data collected in the IR District on trees with 40% to 90% defoliation showed that bud break from post-Jeanne flushes was more than 2 weeks later than from spring and summer 2004 flush. Flushes from the previous spring and summer flowered even when they had no surviving mature leaves. Some post-Jeanne flushes were completely vegetative, although most were able to produce flowers but at a lower level than older shoots.

Keywords


citrus paradisi; 'marsh' and 'flame' grapefruit; 'murcott' tangerine; citrus reticulata × c. sinensis; defoliation; growth flush

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283