Authors
Ronald D.
French-Monar
,
Texas A&M University, Department of Plant Pathology and Microbiology, TAMUS Agricultural Research and Extension Center, 6500 Amarillo Blvd. W, Amarillo 79106
;
Jeffrey B.
Jones
,
University of Florida-IFAS, Plant Pathology Department, Gainesville, FL 32611-0680
;
Monica
Ozores-Hampton
,
University of Florida-IFAS, Southwest Florida Research and Education Center, 2686 State Road 29 North, Immokalee, FL 34142-9515
; and
Pamela D.
Roberts
,
University of Florida-IFAS, Plant Pathology Department, Southwest Florida Research and Education Center, 2686 State Road 29 North, Immokalee, FL 34142-9515
ABSTRACT
From September 2001 until August 2002 and from September 2002 until August 2003, inoculum of Phytophthora capsici consisting of mycelium and oospores was buried in soil under three different soil treatments: soil solarization, fumigation with methyl bromide and chloropicrin, and white-on-black plastic mulch without fumigation or solarization. The effect of these soil treatments on the population and survival of P. capsici was evaluated through time after 28, 63, 119, 175, 245, and 343 days. Three techniques were used for detection of the localized inoculum in soil: soil dilution plating (SDP), a modified soil dilution plating technique with an overlay assay to allow for extra incubation (mSDPO), and lemon leaf baiting of soil (LLB). No viable inoculum was detected from any soil samples from the fumigated plots regardless of the soil detection technique used. By the last sampling date, viable oospore inoculum was still detected in both soil solarization and nontreated soils, but only using mSDPO and LLB. Overall, the mSDPO assay was the most sensitive assay, followed by LLB. Using mSDPO, populations in the last sampling date were 32.9 CFU/g soil for the untreated plots and 14.7 CFU/g soil for the solarized plots. Survival of P. capsici for a year would indicate that oospores have the potential to survive from year to year, and possibly much longer, in Florida and other locations.
