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Poster: Diseases of Plants: New & Emerging Diseases


Phytophthora nicotianae causing foliar blight of Codiaeum variegatum and Zamioculcas zamiifolia in Florida
G. Sanahuja (1), P. Lopez (1), A. Palmateer (1) (1) University of Florida, U.S.A.

Phytophthora is an oomycete plant pathogen, commonly known as a ‘water mold’ that attacks all parts of the host plant, causing root, crown and stem rot and foliar blight. Phytophthora diseases affect numerous ornamentals in nurseries, garden centers and landscapes generally during the hot and humid rainy season in south Florida. Phytophthora nicotianae was isolated for the first time from diseased Codiaeum variegatum (‘variegated’ croton) and Zamioculcas zamiifolia (‘ZZ’ plant) plants. Initially the leaves appeared water soaked and eventually turned dark brown to black in both plants. Morphological characteristics, molecular analysis of the ITS region, and pathogenicity test revealed that P. nicotianae was the causal agent. Tropical foliage plants typically account for the greatest percentage of sales within the ornamental industry and we anticipate these diseases will have a substantial impact on tropical foliage in south Florida. Local tropical foliage producers lost 10% and 35% of croton and ZZ plant production, respectively. Therefore, it is important to enlist the use of effective, registered pesticides to provide preventative control of Phytophthora blight during the periods where consistent outbreaks occur.