Quantitation and Detection of Phytophthora cinnamomi in Avocado Production Areas of South Florida. R. C. Ploetz, University of Florida, IFAS, Tropical Research and Education Center, 18905 SW 280th Street, Homestead 33031. J. L. Parrado, University of Florida, IFAS, Tropical Research and Education Center, 18905 SW 280th Street, Homestead 33031. Plant Dis. 72:981-984. Accepted for publication 28 June 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0981.

Several methods and several agar media were tested for recovery of Phytophthora cinnamomi (cause of Phytophthora root rot of avocado [Persea americana]) in avocado production areas in Florida. Greater recoveries of this pathogen from soil were achieved with McCain’s and PARPH media than with four other previously described semiselective media (P < 0.05). Maximum recovery of P. cinnamomi from avocado roots, however, appeared to be less critical. Similar levels of the pathogen were recovered using one nonselective (PDA) and seven semiselective media or several different methods for treating roots prior to plating on media. The pathogen was recovered equally well from either soil or roots with PARPH. Therefore, either soil or roots may be used for detecting this pathogen in Florida avocado groves.

Keyword(s): avocado root rot, Pythium spp.