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| Web URL(s): | http://archive.lib.msu.edu/tic/rpr/1996/Turfgrass/46990,%20U%20Florida,%20Giblin-Davis.PDF
Last checked: 11/07/2013
Requires: PDF Reader |
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| Publication Type:
| Report |
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| Material Type: | Manuscript |
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| Monographic Author(s): | Giblin-Davis, Robin M.; Dickson, Don W.; Cisar, John L. |
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| Author Affiliation: | Giblin-Davis and Cisar: Ft. Lauderdale Research and Education Center, University of Florida, Ft. Lauderdale; and Giblin-Davis and Dickson: Department of Entomology and Nematology, University of Florida, Gainesville, FL |
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| Monograph Title: | Pasteuria sp. for Biological Control of the Sting Nematode, Belonolaimus longicaudatus, in Turfgrass: [1996 Final Research Report], 1996. |
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| Publishing Information: | Gainesville, Florida: University of Florida |
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| # of Pages: | 26 |
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| Collation: | 11, [15] pp. |
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| Abstract/Contents: | "We are describing a new species of bacterium in the genus, Pasteuria discovered parasitizing the sting nematode, Belonolaimus longicaudatus in Florida. This obligate bacterial parasite of nematodes (Pasteuria n. [S-1]) may have potential for inoculative biological control in golf course greens against the sting nematode; a destructive ectoparasite that can reduce the root dry weight of turfgrasses and other crops in sandy soils by as much as 30-50%. In 1996, we completed ultrastructural studies with transmission electron microscopy (TEM) and low-temperature and regular scanning electron microscopy (SEM) that show that Pasteuria n. sp. (S-1) is a new species. We have elucidated the development and life cycle of this bacterium with excellent photomicrographs over the past 3 years. In 1995, we began a monthly survey of 6 different sites of 'Tifdwarf' and 'Tifgreen' hybrid bermudagrass (fairway conditions) at the Ft. Lauderdale Research and Education Center where Pasteuria n. sp. occurs naturally at different levels to monitor its suppressive effects on sting nematode populations at three different soil depths. Soil temperature was also monitored at these different depths. After 18 months of sampling, we have documented what appear to be epizootics of the sting nematode caused by the Pasteuria n. sp. Locations that started with low levels of spore encumberance have shown increases in the numbers of nematodes encumbered with spores and a decrease in the total sting nematode numbers. Areas that started with high encumberance levels, suggesting that Pasteuria n. sp. was established, have continued to be suppressive in what appears to be a density dependent manner. In 1996 a Pasteuria n. sp. spore encumberance bioassay was developed using spores extracted from spore-filled cadavers and inoculated into 1 gm of soil in tubes at different doses (0, 10, 100, 500, 1000, 5000, 10,000, and 100,000 spores). Ten sting nematodes were then inoculated into the soil and incubated at 25 C for 21 days, and extracted and stained and counted for spore-encumberance levels. These data are being used for a model to estimate spore-densities from unknown soils. In 1994-1995, our 390 day lab study demonstrated that inoculative release of Pasteuria n. sp. encumbered sting nematodes was unacceptable for establishment and population suppression of healthy sting nematodes. Therefore, a field study was undertaken in 1996 to determine whether inoculation of Pasteuria n. sp.-infested soil from one of the survey areas which appeared to be suppressive had any promise. Soil was collected and pooled from a heavily Pasteuria n. sp.-infested area near to location E from the field epizootic study. The spore encumberance bioassay was used to estimate the numbers of spores in the randomly mixed and dried soil. There were two treatments of the soil; 1) control soil that was autoclaved for 2 hours, killing all nematodes and Pasteuria n. sp., and 2) soil heated to 47 C for 48 hours to kill the sting nematodes but not the Pasteuria n. sp. A plot of 'Tifdwarf' bermudagrass was divided up into a grid of 1 m2 plots with 15 cm borders. Precounts of sting nematodes present per 100 cm3 subsamples were taken using the sugar flotation method. Plots were ranked according to sting nematode density and treatments were randomly assigned within ranks. A 15 cm diam. cup cutter was used to remove a core from the center of each 1 m2 plot. Soil (900 cm3) was removed and replaced with an equal volume of the assigned treated soil. The core was then replaced and leveled. Six months after inoculation, sting nematode densities were statistically equal for both treatments. However, there was a significant difference in the proportion of sting nematodes encumbered (90% vs. 70%) and filled (5% vs. 1% for the heat-treated vs. autoclaved soil treatments, respectively) with Pasteuria n. sp. endospores. These data suggest that Pasteuria n. sp. was present but undetected before the experiment was started and that the inoculation of soil was successful at establishing the Pasteuria n. sp. in the turfgrass ecosystem. We are continuing to monitor the spread (increase of the radius of the Pasteuria n. sp. infection) and whether sting nematode densities are suppressed by the bacterial disease over time in a golf course green." |
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| Language: | English |
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| References: | 0 |
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| See Also: | See also related summary article "Pasteuria sp. for biological control of the sting nematode, (Belonolaimus longicaudatus), in turfgrass" 1996 Turfgrass and Environmental Research Summary, 1996, pp. 54-56, R=46990. R=46990 |
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| Note: | Partial reprint appears in Turfgrass Research in Florida: A Technical Report, May 1996, p. 95-103
Also appears as pp. 00423-00448 in the USGA Turfgrass Research Committee Reporting Binders for 1996.
"1996 USGA Final Turfgrass Research Report"
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Last checked: 11/07/2013
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