Belonolaimus longicaudatus is a serious problem on bermudagrass, a common warm-season turfgrass, in Florida. The cancellation of organophosphate nematicides necessitates that new management tools be identified for use on sports turf. Postplant application of 1,3-dichloropropene (1,3-D) on bermudagrass was evaluated for management of B. longicaudatus on golf course fairways and driving ranges. A series of 10 experiments were conducted to evaluate the effectiveness of 1,3-D in reducing population densities of B. longicaudatus and enhancing bermudagrass recovery from nematode damage. In 5 of 10 experiments, 1,3-D injected at 46.8 liters/ha was effective in reducing population densities of B. longicaudatus (P < 0.05) compared to untreated plots 2 to 4 weeks after treatment. One month after treatment, population densities of B. longicaudatus ranged from 59% to 97% of those in untreated plots. Nematode suppression generally lasted 2 months or less. Turf visual performance was improved following injection with 1,3-D (P < 0.05) over untreated plots when other factors were not limiting. Turf root development also was enhanced following injection with 1,3-D. Postplant injection of 1,3-D could be a useful nematode management tool for certain sports turf applications.
Belonolaimus longicaudatus; bermudagrass; Cynodon dactylon; Cynodon hybrids; 1,3-dichloropropene; nematicide; nematode; nematode management; soil fumigation; sting nematode; turf
Plant-parasitic nematodes are important pathogens of intensely-managed turf used on golf courses. Two of these nematodes that are common in the southeastern US are Belonolaimus longicaudatus and Mesocriconema ornata. Currently, there is a lack of effective treatments that can be used to manage these important pests. Turfgrass field trials evaluated DL-methionine as a turfgrass nematicide against B. longicaudatus and M. ornata. One trial was on a bermudagrass putting green, the other was on zoysiagrass maintained under putting-green conditions. Two rates of methionine, 1120 kg/ha in a single application, and 112 kg/ha applied twice four weeks apart, were compared with untreated control and fenamiphos treatments. Measurements collected included soil nematode counts, turf density, and root lengths. In both trials, 1120 kg/ha of methionine reduced numbers of both nematode species (P ≤ 0.1), and 112 kg/ha of methionine reduced numbers of both nematode species after two applications. Bermudagrass turf density responded favorably to both methionine rates and root lengths were improved by the 1120 kg/ha rate. Zoysiagrass showed short-term phytotoxicity to methionine, but quickly recovered and treated plots were improved compared to the untreated controls by the end of the trial. These trials indicated that methionine has potential for development as a turfgrass nematicide, but further research is needed to determine how it can best be used.
Belonolaimus longicaudatus; bermudagrass; Cynodon; Mesocriconema ornata; nematode management; ring nematode; sting nematode; turfgrass; Zoysia; zoysiagrass
Belonolaimus longicaudatus and Helicotylenchus pseudorobustus are among the most common nematode parasites of turfgrasses in Florida. Bermudagrass (Cynodon dactylon × C. transvaalensis) and seashore paspalum (Paspalum vaginatum) are the two turf species most commonly used on Florida golf courses. This paper explores the interactions between B. longicaudatus and H. pseudorobustus on bermudagrass and seashore paspalum hosts. Data collected from thousands of nematode samples submitted to the Florida Nematode Assay Lab over a 8-yr period revealed a negative relationship between B. longicaudatus and H. pseudorobustus on bermudagrass, but not seashore paspalum. In a multi-year field plot experiment using multiple cultivars of bermudagrass, and seashore paspalum B. longicaudatus and H. pseudorobustus were negatively related on both turf species. Greenhouse trials where multiple cultivars of both turf species were inoculated with different combinations of B. longicaudatus and H. pseudorobustus found that each nematode species was inhibitory to the other on both host species. Belonolaimus longicaudatus and H. pseudorobustus clearly impact each other on turfgrass hosts, although the mechanism of the nematode-nematode interactions is unknown.
Belonolaimus longicaudatus; bermudagrass; Cynodon dactylon; Helicotylenchus pseudorobustus; interaction; Paspalum vaginatum; seashore paspalum; spiral nematode; sting nematode; turfgrass
Belonolaimus longicaudatus is an important parasite of both warm-season bermudagrass and winter overseed grasses used on golf courses in the southeastern United States. Field trials were conducted to study the effects of a commercial formulation of Paecilomyces lilacinus strain 251 applied to overseed grasses during the winter and early spring on population density of B. longicaudatus and bermudagrass health in late spring after bermudagrass broke dormancy. These studies found that P. lilacinus reduced numbers of B. longicaudatus in most cases, but not below damaging levels. Multiple applications of 1 × 1010 spores/m2 were generally more effective than 2 × 1010 spores/m2 in reducing nematode numbers and improving turf roots. These results indicate that application of this formulation of P. lilacinus strain 251 to overseeded turf in the spring may be a useful integrated pest management tool for B. longicaudatus on bermudagrass, but is not sufficient as a stand-alone nematode management tactic.
Belonolaimus longicaudatus; bermudagrass; biological control; Paecilomyces lilacinus, sting nematode; turfgrass
Three nematicides were evaluated for control of Belonolaimus longicaudatus, Hoplolaimus galeatus, Criconemella spp., and Meloidogyne spp. in 'Tifgreen II' bermudagrass mowed at golf course fairway height (1.3 cm) in Fort Lauderdale, Florida. Bermudagrass plots were treated with fenamiphos (13.5 kg a.i./ha), oxamyl (13.5 kg a.i./ha), or 30% formaldehyde (6.4 liter a.i./ha). The plots treated with fenamiphos or formaldehyde were split 14 days later and one-half of each plot received two biweekly applications of formaldehyde. Forty-two days after the treatments were applied, the turfgrass vigor ratings and dry root weights in plots treated with fenamiphos were higher (P < 0.05) than the control, oxamyl, or formaldehyde treatments. The population levels of B. longicaudatus were suppressed (P < 0.05) in the fenamiphos, fenamiphos plus formaldehyde, and oxamyl treatments.
Belonolaimus longicaudatus; bermudagrass; chemical control; Criconemella spp.; fenamiphos; formaldehyde; lance nematode; Hoplolaimus galeatus; Meloidogyne spp.; oxamyl; ring nematode; root-knot nematode; sting nematode; turfgrass
Plant-parasitic nematodes can be very damaging to turfgrasses. The projected cancellation of the registration for fenamiphos in the near future has generated a great deal of interest in identifying acceptable alternative nematode management tactics for use on turfgrasses. Two field experiments were conducted to evaluate the effectiveness of repeated applications of several commercially available nematicides and root biostimulants for reducing population densities of plant-parasitic nematodes and (or) promoting health of bermudagrass in nematode-infested soil. One experimental site was infested with Hoplolaimus galeatus and Trichodorus obtusus, the second with Belonolaimus longicaudatus. In both trials, none of the experimental treatments reduced population densities (P ≤ 0.1) of plant-parasitic nematodes, or consistently promoted turf visual performance or turf root production. Nematologists with responsibility to advise turf managers regarding nematode management should thoroughly investigate the validity of product claims before advising clientele in their use.
Belonolaimus longicaudatus; bermudagrass; Cynodon dactylon; Hoplolaimus galeatus; lance nematode; sting nematode; stubby-root nematode; Trichodorus obtusus; turf
Field experiments evaluated the effects of nematicide and fertility on performance of ‘Tifway 419’ bermudagrass parasitized by the sting nematode (Belonolaimus longicaudatus). Plot treatments were nontreated or nematicide (1,3-dichloropropene) treated combined with different nitrogen (N) fertilizer levels. Effects of treatments on numbers of B. longicaudatus and turf performance were compared. Nematicide consistently reduced numbers of B. longicaudatus, but fertilizer level had no effect on B. longicaudatus. Turf performance of nematicide-treated plots was improved compared with nontreated plots during both experiments. Increasing N fertilizer level improved turf performance in nematicide-treated plots in some cases, but had no effect on turf performance in nontreated plots in either experiment. Results suggest that increasing N fertilizer levels may not improve turf performance at sites infested with B. longicaudatus unless nematode management tactics are effective in reducing nematode densities.
Belonolaimus longicaudatus; bermudagrass; Cynodon dactylon; fertilizer; nitrogen; sting nematode; turfgrass; management; turf quality
The effect of nematode population density at the time of application and formulations of in vitro-produced Pasteuria spp. endospores on the final population density of Belonolaimus longicaudatus was studied in an 84-d-long pot bioassay. The experiment utilized a factorial design consisting of 30 or 300 B. longicaudatus /100 cm3 of sandy soil and three formulations of in vitro-produced Pasteuria spp. endospores (nontreated, granular, or liquid). No differences were observed in percent endospore attachment between nematode inoculum levels during either trial. Granular and liquid formulations of in vitro-produced endospores suppressed nematode population densities by 22% and 59% in the first trial and 20% and 63% in the second, respectively compared with the nontreated control. The liquid formulation increased percent endospore attachment by 147% and 158%, respectively, compared with the granular formulation. The greatest root retention by the host plant was observed at the lower B. longicaudatus inoculation level following application of the liquid formulation. While both the granular and liquid formulations reduced B. longicaudatus population densities in the soil, the liquid spore suspension was most effective.
Belonolaimus longicaudatus; biological control; formulation; management; Pasteuria spp.; sting nematode; suppression; turfgrass
Seashore paspalum (Paspalum vaginatum) has great potential for use in salt-affected turfgrass sites. Use of this grass on golf courses, athletic fields, and lawns in subtropical coastal areas may aid in conservation of freshwater resources. Belonolaimus longicaudatus and Hoplolaimus galeatus are considered among the most damaging root pathogens of turfgrasses in Florida. Glasshouse experiments were performed in 2002 and 2003 to examine the effects of increasing levels of irrigation salinity on B. longicaudatus and H. galeatus. Irrigation treatments were formulated by concentrating deionized water to six salinity levels (0, 5, 10, 15, 20, and 25 dS/m). Final population densities of H. galeatus followed a negative linear regression (r² = 0.92 and 0.83; P <= 0.01) with increasing salinity levels. Final population densities of B. longicaudatus were quadratically (r² = 0.72 and 0.78; P <= 0.01) related to increasing salinity levels from 0 to 25 dS/m. An increase in population densities of B. longicaudatus was observed at moderate salinity levels (10 and 15 dS/m) compared to 0 dS/m. Root-length comparisons revealed that B. longicaudatus caused root stunting at low salinity levels, 0 to 10 dS/m, but roots were not affected at 15 to 25 dS/m. These results indicate that the ability of B. longicaudatus to feed and stunt root growth was negatively affected at salinity levels of 15 dS/m and above.
Belonolaimus longicaudatus; Hoplolaimus galeatus; lance nematode; Paspalum vaginatum; salinity; seashore paspalum; sting nematode
Glyphosate-tolerant cotton cultivars were evaluated for tolerance to Belonolaimus longicaudatus in field experiments conducted from 2004 to 2005. Field trials were arranged in a split-plot design that included treatment with four levels of 1, 3-dichloropropene (0.0, 13.9, 27.8, and 41.7 1 a.i./ha) to establish a range of population densities of B. longicaudatus. Six cotton cultivars (early-to-mid maturity: DP444BG/RR SG501BR, ST5242BR; mid-to late maturity: DP451B/RR, ST5599BR, DP655BRR) were planted as whole plots. Fumigation was effective in suppressing B. longicaudatus population densities at mid-season, but not at cotton harvest, and increased cotton lint yield. The cultivar × fumigation interaction for cotton lint yield was not significant for the six cultivars evaluated, indicating that tolerance did not occur in this nematode-host combination. Early-to-mid maturity cultivars yielded significantly more than mid-to-late maturity cultivars in both years. Small but significant differences in nematode final population density were observed between cultivars that may be related to relative maturity.
Belonolaimus longicaudatus; cotton; crop loss; 1; 3-dichloropropene; fumigant nematicide; Gossypium hirsutum; glyphosate; herbicide-tolerant crops; host-plant tolerance; nematode; sting nematode; transgenic
One hundred and eleven golf courses from 39 counties in the Carolinas were surveyed for plant-parasitic nematodes. Species diversity within habitats was analyzed with five diversity indices including Diversity index (H’), Evenness (J’), Richness (SR), Dominance (λ) and Diversity (H2). The results revealed a remarkably high diversity of 24 nematode species belonging to 19 genera and 11 families. Of those, 23 species were found in SC, 19 species in NC, and 18 species were detected in both states. Helicotylenchus dihystera, Mesocriconema xenoplax, Hoplolaimus galeatus, Tylenchorhynchus claytoni, Belonolaimus longicaudatus, Meloidogyne graminis and Paratrichodorus minor were the most prevalent and abundant species in golf course turfgrasses in both states. Twelve species were new records of plant parasitic nematodes in turfgrasses in both NC and SC. The results also revealed effects of different habitats on diversity of nematode species in turfgrass ecosystem. H’ and SR values were higher in SC than in NC. H’, J’ and H2 values were significantly higher in sandy than in clay soil in NC, but no significant differences between sand and clay soil were detected in SC or in pooled data from both states. There were no significant differences for all indices among the management zones (putting green, fairway and tee) in NC. However, in SC and pooled data, H’, SR and H2 were significantly higher in putting greens than in fairways and tees. Significant differences from different grass species (bermudagrass, creeping bentgrass and zoysiagrass) were detected only in H’, which was significantly higher in zoysiagrass than in bentgrass or bermudagrass in NC. In pooled data, H’ was significantly higher in zoysiagrass samples than in creeping bentgrass samples but was not significantly different from bermudagrass samples.
North Carolina; South Carolina; detection; distribution; diversity; ecology; golf course; identification; plant-parasitic nematode; turfgrass
Belonolaimus longicaudatus has long been recognized as a pathogen of potato (Solanum tuberosum). However, a damage function relating expected yield of potato to population densities of B. longicaudatus at planting has not been derived, and the economic threshold for nematicide application is unknown. The objectives of this study were to derive the damage function of B. longicaudatus on potato and to calculate the economic threshold population density. The damage function data for B. longicaudatus on potato were obtained from an ongoing field study to evaluate cropping systems and nematode management practices. Soil samples were collected from experimental field plots, and nematodes were extracted from a 130-cm³ subsample with a centrifugal-flotation method. A damage function was derived by linear regression of potato yield on nematode population density at planting. Based on this derived damage function and published potato prices, the economic threshold for nematicide application was calculated at 2 to 3 B. longicaudatus/130 cm³ of soil, which was near the detection threshold based on methodology used in this study.
Belonolaimus longicaudatus; damage function; economic threshold; nematode; plant disease loss; potato; Solanum tuberosum; sting nematode
Experiments were conducted to quantify the effects of the sting nematode (Belonolaimus longicaudatus) on root reductions and quantity of nitrate (NO3
−) leached from ‘Tifdwarf’ bermudagrass in lysimeters. Forty lysimeters were planted with ‘Tifdwarf’ bermudagrass, of which 20 were inoculated with B. longicaudatus and 20 were noninoculated. Root length was compared between treatments at six, 12, and 18 weeks after initiation of the experiments. Turf was fertilized every three weeks, and leaching events were simulated at 21 and 42-day intervals in trial one and trial two, respectively. Leachate was collected, and the quantity of NO3
− leached was compared between treatments. Root reductions were observed in lysimeters inoculated with B. longicaudatus at all evaluation dates. Quantity of NO3
− leached was greater in inoculated lysimeters at the 18-week evaluation during both trials. This study indicates that nematode damage to turf roots limits root vigor and N uptake, thereby increasing nitrate leaching, adding to water quality concerns.
Belonolaimus longicaudatus; bermudagrass; Cynodon dactylon; nitrate leaching; sting nematode; turfgrass; management; water quality
Portions of a 'Tifgreen' bermudagrass golf green with poor turf and large numbers of Belonolabnus longicaudatus and Criconemella ornata were treated with selected nematicides in the summers of 1977 and 1978. Improvements in turf quality were observed within 4 wk after treatment with phenamiphos and fensulfothion. Treatment with phenamiphos restulted in lower numbers of B. longicaudatus 4 and 14 wk after treatment in the 1977 experiment and up to 1 yr after treatment in the 1978 experiment. Treatment with fensulfothion reduced the number of B. longicaudatus for only 1 month after treatment and significantly increased the numbers of this nematode in September and March in the 1978 experiment, Negative correlations were obtained between numbers of B. longicaudatus and turf qualily up to 1 yr. Numbers of C. ornata were reduced only in January and June following treatment with phenamiphos and not at any time with fensulfothion. Treatment with fensulfothion resulted in higher numbers of this nematode than in check plots in November and March. The percent area covered by prostrate spurge the following year was reduced following treatment with phenamiphos, but not with fensulfothion.
phenantiphos; fensulfothion; DBCP; sting nematodes; ring nematodes
The effects of soil solarization and ammonium bicarbonate or ammonium sulfate against plant-parasitic nematodes on yellow squash (Cucurbita pepo) and on vinca (Catharanthus roseus) were evaluated at two sites. Solarization for 3 weeks in the spring suppressed population levels of Belonolaimus longicaudatus, Criconemella spp., and Dolichodorus heterocephalus throughout the growing season on both crops at both sites. Levels of Meloidogyne incognita were suppressed initially, but population densities increased by the end of the crop in several cases. In one site, numbers of Paratrichodorus minor resurged following solarization to levels that were greater than those present in unsolarized control plots. The effect of solarization was not enhanced by combination with ammonium amendments, but, in one site, application of ammonium bicarbonate or ammonium sulfate resulted in lower numbers of B. longicaudatus than in the unamended control. Additional research and improved efficacy of candidate amendments are required before they can be successfully integrated with solarization for nematode management. Efficacy of solarization against plant-parasitic nematodes was achieved despite a relatively short (3 weeks) solarization period.
ammonium bicarbonate; ammonium sulfate; Belonolaimus longicaudatus; Catharanthus roseus; Cucurbita pepo; Dolichodorus heterocephalus; integrated pest management; Meloidogyne incognita; nematode; Paratrichodorus minor; squash; sustainable agriculture; vinca
A greenhouse population of the sting nematode, Belonolaimus longicaudatus, obtained from an infested golf course in California's Coachella Valley, was surface-decontaminated and cuhured on excised roots of Zea mays supported by Gamborg's B5 medium. At 26-27 °C the females laid eggs, and newly emerged juveniles of the second generation completed three molts within 29 days after egg deposition. Sixty days after inoculation with 60 females and 40 males, an average of 529 nematodes and 83 eggs were recovered from the culture. The feeding process consisted of probing, stylet penetration, ingestion, and stylet retraction. Feeding seemed to be necessary before egg deposition or molting occurred. The sting nematode was observed feeding exclusively as an ectoparasite and preferably at the region of cell division and elongation. Vigorous feeding by many nematodes usually caused discoloration of root tips and termination of growth.
Belonolaimus longicaudatus; corn root culture; feeding behavior; in vitro culture; nematode; sting nematode; Zea mays
With the cancellation of fenamiphos in the near future, alternative nematode management tactics for plant-parasitic nematodes (PPN) on golf courses need to be identified. The use of entomopathogenic nematodes (EPN) has been suggested as one possible alternative. This paper presents the results of 10 experiments evaluating the efficacy of EPN at managing PPN on turfgrasses and improving turf performance. These experiments were conducted at various locations throughout Florida over the course of a decade. In different experiments, different EPN species were tested against different species of PPN. Separate experiments evaluated multiple rates and applications of EPN, compared different EPN species, and compared single EPN species against multiple species of PPN. In a few trials, EPN were associated with reductions in certain plant-parasite species, but in other trials were associated with increases. In most trials, EPN had no effect on plant parasites. Because EPN were so inconsistent in their results, we conclude that EPN are not acceptable alternatives to fenamiphos by most turf managers in Florida at this time.
Belonolaimus longicaudatus; bermudagrass; biological control; Cynodon dactylon; entomopathogenic nematode; Helicotylenchus microlobus; Hemicriconemoides annulatus; Heterorhabditis spp.; Hoplolaimus galeatus; lance nematode; Mesocriconema ornata; ring nematode; sheathoid nematode; spiral nematode; Steinernema spp.; sting nematode; stubby-root nematode; Trichodorus obtusus; turf
Efficacy of the fumigants ethylene dibromide (EDB), EDB + chloropicrin, and 1,3-dichloropropene (1,3-D) applied with one or three chisels per row, singly or in combination with aldicarb, was evaluated in 1982 and 1983 on potato (Solanum tuberosum) cultivars Atlantic and Sebago for control of several nematodes, including Belonolaimus longicaudatus, Meloidogyne incognita, and trichodorids. Generally, nematode populations were lowest following application of fumigants with three chisels per row, following EDB or EDB + chloropicrin, and when fumigants were applied in combination with aldicarb. These treatment combinations also resulted in highest yields in 1983. Cosmetic appearance of tubers was improved (P ≤ 0.05) by aldicarb in 1982. Both bacterial wilt and nematodes reduced yield; however, stepwise multiple regression analysis estimated that the greater loss in yield was associated with bacterial wilt, especially in Atlantic during 1983. Economic analysis showed that addition of aldicarb to all 1,3-D treatments increased profits. The increase was greater in Atlantic than in Sebago. Triple-chisel fumigation produced greater profits than single-chisel fumigation in Atlantic during both years and in Sebago in 1982.
aldicarb; bacterial wilt; Belonolaimus longicaudatus; corky ringspot; Meloidogyne incognita; Paratrichodorus minor; potato; Pseudomonas solanacearum; soil fumigation; Solanum tuberosum; tobacco rattle virus; trichodorid; Trichodorus proximus; Trichodorus viruliferous
A survey was conducted between 1985 and 1989 of isolates of the Pasteuria penetrans group on phytoparasitic nematodes in bermudagrass (Cynodon spp.) turf in southern Florida. Six different isolates of the P. penetrans group were observed from five different species of phytoparasitic nematode hosts. Five of the bacterial isolates were different (P ≤ 0.01) in sporangium diameter, endospore width, and ratio of sporangium diameter to endospore width. All locations surveyed had one or more isolates present, suggesting that the Pasteuria penetrans group is widespread in its distribution in southern Florida. Three survey sites had high densities of Belonolaimus longicaudatus, with more than 60% of the host population encumbered with a large-spored isolate of Pasteuria (mean sporangium diameter = 6.10 μm). One of these sites was monitored for 16 months during which the proportion of nematodes encumbered with this Pasteuria isolate remained constant. Soil infested with this isolate was not suppressive to Pasteuria-free populations of B. longicaudatus grown on bermudagrass for 6 months after controlled soil inoculation. However, the proportion of spore-encumbered and parasitized B. longicaudatus after 6 months was 73%, which was similar to the 74% level observed at the field site. The uhrastructure of mature sporangia of the large-spored isolates of Pasteuria from B. longicaudatus and Hoplolaimus galeatus is described and compared with ultrastructural descriptions of P. penetrans sensu strictu and P. thornei from the literature. These B. longicaudatus and H. galeatus isolates of Pasteuria appear to be distinct from the known species and may warrant new species status.
bacterial parasite; Belonolaimus longicaudatus; bermudagrass; biological control; Helicotylenchus microlobus; Hoplolaimus galeatus; Meloidogyne spp.; Pasteuria penetrans group; Tylenchorhynchus annulatus; ultrastructure
Belonolaimus longicaudatus and Helicotylenchus spp. are damaging nematode species on bermudagrass (Cynodon spp.) and seashore paspalum (Paspalum vaginatum) in sandy soils of the southeastern United States. Eight bermudagrass and three seashore paspalum cultivars were tested for responses to both nematode species in field plots for two years in Florida. Soil samples were taken every three months and nematode population densities in soil were quantified. Turfgrass aboveground health was evaluated throughout the growing season. Results showed that all bermudagrass cultivars, except TifSport, were good hosts for B. longicaudatus, and all seashore paspalum cultivars were good hosts for H. pseudorobustus. Overall, bermudagrass was a better host for B. longicaudatus while seashore paspalum was a better host for H. pseudorobustus. TifSport bermudagrass and SeaDwarf seashore paspalum cultivars supported the lowest population densities of B. longicaudatus. Seashore paspalum had a higher percent green cover than bermudagrass in the nematode-infested field. Nematode intolerant cultivars were identified.
Belonolaimus longicaudatus; bermudagrass; Cynodon spp.; field; Helicotylenchus spp.; Paspalum vaginatum; resistance; seashore paspalum; spiral nematodes; sting nematodes
Pasteuria sp., strain S-1, is a gram-positive, obligate endoparasitic bacterium that uses the phytoparasitic sting nematode, Belonolaimus longicaudatus, as its host in Florida. The host attachment of S-1 appears to be specific to the genus Belonolaimus with development occurring only in juveniles and adults of B. longicaudatus. This bacterium is characterized from other described species of Pasteuria using ultrastructure of the mature endospore. Penetration, development, and sporogenesis were elucidated with TEM, LTSEM, and SEM and are similar to other nematode-specific Pasteuria. Recent analysis of 16S rDNA sequence homology confirms its congeneric ranking with other Pasteuria species and strains from nematodes and cladocerans, and corroborates ultrastructural, morphological, morphometric, and host-range evidence suggesting separate species status.
Belonolaimus longicaudatus; development; obligate nematode endoparasitic bacterium; Pasteuria sp. (s-1 strain); sporogenesis; sting nematode; ultrastructure
A fine-textured, dwarf St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) genotype, FX-313, was severely damaged in plots in the third year of evaluation in sandy soil in southern Florida. Damage was associated with numerous (> 40/100-cm³ soil) sting nematodes, Belonolaimus longicaudatus Rau. Damage was ameliorated (P < 0.05) by fenamiphos applied broadcast at 2.2 g a.i./m², and B. longicaudatus numbers were reduced (P < 0.01), compared with untreated plots. Root dry weights of four diploid (2n = 18) St. Augustinegrasses--FX-261, FX-299, FX-313, and Seville--were reduced (P < 0.001) by B. longicaudatus in a temperature- and light-controlled experiment. Estimated daily transpiration, an indicator of plant health, was reduced (P < 0.001) after 112 days to 3.32 g/pot for inoculated plants, compared with 5.10 g /pot for uninoculated plants. Genotypes did not differ in nematode number per pot (mean 551/215 cm² soil) 128 days after inoculation, but differed (P < 0.05) in nematode numbers on a root dry weight basis, with FX-313 and Seville representing the extremes, 12,300 and 4,000 B. longicaudatus/g root dry weight, respectively. The diploid St. Augustinegrasses evaluated were good hosts for B. longicaudatus, but field data and controlled inoculation demonstrate genetic variation in susceptibility.
Belonolaimus longicaudatus; breeding; fenamiphos; nematode; resistance; St. Augustinegrass; Stenotaphrum secundatum; sting nematode; turfgrass
Belonolaimus longicaudatus and Hoplolaimus galeatus are considered among the most damaging pathogens of turfgrasses in Florida. However, the host status of seashore paspalum (Paspalum vaginatum) is unknown. Glasshouse experiments were performed in 2002 and 2003 to determine the tolerance of 'SeaIsle 1' seashore paspalum to a population of B. longicaudatus and a population of H. galeatus, and to compare to 'Tifdwarf' bermudagrass for differences. Both nematode species reproduced well on either grass, but only B. longicaudatus consistently reduced root growth as measured by root length. Belonolaimus longicaudatus reduced root growth (P ≤ 0.05) by 35% to 45% at 120 days after inoculation on both grasses. In 2003, higher inoculum levels of H. galeatus reduced root growth (P ≤ 0.05) by 19.4% in seashore paspalum and by 14% in bermudagrass after 60 and 120 days of exposure, respectively. Percentage reductions in root length caused by H. galeatus and B. longicaudatus indicated no differences between grass species, although Tifdwarf bermudagrass supported higher soil population densities of both nematodes than SeaIsle 1 seashore paspalum.
Belonolaimus longicaudatus; bermudagrass; Hoplolaimus galeatus; host status; lance nematode; Paspalum vaginatum; seashore paspalum; sting nematode; tolerance
Pasteuria strain S-1 was found to parasitize the sting nematode Belonolaimus longicaudatus. S-1 spores attached to several strains of B. longicaudatus from different geographical locations within the United States. However, they did not adhere to any of the following species: Heterodera schachtii, Longidorus africanus, Meloidogyne hapla, M. incognita, M. javanica, Pratylenchus brachyurus, P. scribneri, P. neglectus, P. penetrans, P. thornei, P. vulnus, and Xiphinema spp. The 16S rRNA genes from Pasteuria strain S-1 and P. penetrans strain Pp from Senegal were obtained by PCR amplification. A DNA sequence analysis showed that the S-1 16S rRNA had 96% or less similarity to the 16S rRNA genes from all previously reported Pasteuria species. Diverse phylogenetic methods all provided robust support for an association of Pasteuria strain S-1, Pasteuria strain NA parasitic to H. glycines, and P. penetrans strain Pp, to the exclusion of P. ramosa. In addition, our study showed intraspecific variation within P. penetrans as inferred by its 98% similarity to P. penetrans strain Pp.
Belonolaimus longicaudatus; microparasite; Pasteuria sp.; P. penetrans; phylogeny; taxonomy; 16S rDNA sequence
Sting nematode (Belonolaimus longicaudatus) is recognized as a pathogen of cotton (Gossypium hirsutum), but the expected damage from a given population density of this nematode has not been determined. The objective of this study was to quantify the effects of increasing initial population densities (Pi) of B. longicaudatus on cotton yield and root mass. In a field plot study, nematicide application and cropping history were used to obtain a wide range of Pi values. Cotton yields were regressed on Pi density of B. longicaudatus to quantify yield losses in the field. In controlled environmental chambers, cotton was grown in soil infested with increasing Pi's of B. longicaudatus. After 40 days, root systems were collected, scanned on a desktop scanner, and root lengths were measured. Root lengths were regressed on inoculation density of B. longicaudatus to quantify reductions in the root systems. In the field, high Pi's (>100 nematodes/130 cm³ of soil) reduced yields to near zero. In controlled environmental chamber studies, as few as 10 B. longicaudatus/130 cm³ of soil caused a 39% reduction in fine cotton roots, and 60 B. longicaudatus/130 cm³ of soil caused a 70% reduction. These results suggest that B. longicaudatus can cause significant damage to cotton at low population densities, whereas at higher densities crop failure can result.
Belonolaimus longicaudatus; cotton; crop loss; damage function; damage threshold; Gossypium hirsutum; nematode; plant disease loss; root scanning; sting nematode