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
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
In 2010, a turfgrass bionematicide containing in vitro produced Pasteuria sp. for management of Belonolaimus longicaudatus was launched under the tradename Econem™. Greenhouse pot studies and field trials on golf course fairways and tee boxes evaluated Econem at varied rates and application frequencies. Trials on putting greens compared efficacy of three applications of Econem at 98 kg/ha to untreated controls and 1,3-dichloropropene at 53 kg a.i/ha. Further putting green trials evaluated the ability of three applications of Econem at 98 kg/ha to prevent resurgence of population densities of B. longicaudatus following treatment with 1,3-dichloropropene at 53 kg a.i./ha. None of the Econem treatments in pot studies were effective at reducing B. longicaudatus numbers (P ≤ 0.05). Econem was associated with reduction in population densities of B. longicaudatus (P ≤ 0.1) on only a single sampling date in one of the eight field trials and did not improve turf health in any of the trials (P > 0.1). These results did not indicate that Econem is an effective treatment for management of B. longicaudatus on golf course turf.
Belonolaimus longicaudatus; bermudagrass; biological control; biopesticide; Cynodon spp.; nematode management; Pasteuria sp.; sting nematode; turfgrass
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
The possibility that neutrophils produce the hydroxyl radical (OH-) was studied by examining the ability of these cells to support the release of ethylene from methional, a reaction in which it has been shown that OH-, but not O2- or H2O2, may serve as the oxidizing agent. When neutrophils were exposed to opsonized zymosan in the presence of 0.35 mM methional, ethylene was released in quantities amounting to 44.6+/-3.6 pmol/10(6) cells/40 min. Ethylene production required the presence of neutrophils, opsonized zymosan, and methional, indicating that it was formed from methional by stimulated but not resting neutrophils. Ethylene was not produced by zymosan-treated cells from patients with chronic granulomatous disease, confirming the requirement for respiratory burst activity in this process. Ethylene production was suppressed by benzoic acid, an OH- scavenger. Superoxide dismutase (3 microgram/ml) reduced ethylene production to 21% of control levels, but catalase had no significant effect in this system. These findings indicate that stimulated neutrophils produce a highly reactive oxidizing radical, possibly OH-, which releases ethylene from methional, and that the O2-generated during the respiratory burst is involved in the production of this reactive species.
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
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
Creeping bentgrass (Agrostis stolonifera, allotetraploid 2n = 4x = 28) is one of the major cool-season turfgrasses. It is widely used on golf courses due to its tolerance to low mowing and aggressive growth habit. In this study, we investigated genome relationships of creeping bentgrass relative to the Triticeae (a consensus map of Triticum aestivum, T. tauschii, Hordeum vulgare, and H. spontaneum), oat, rice, and ryegrass maps using a common set of 229 EST-RFLP markers. The genome comparisons based on the RFLP markers revealed large-scale chromosomal rearrangements on different numbers of linkage groups (LGs) of creeping bentgrass relative to the Triticeae (3 LGs), oat (4 LGs), and rice (8 LGs). However, we detected no chromosomal rearrangement between creeping bentgrass and ryegrass, suggesting that these recently domesticated species might be closely related, despite their memberships to different Pooideae tribes. In addition, the genome of creeping bentgrass was compared with the complete genome sequence of Brachypodium distachyon in Pooideae subfamily using both sequences of the above-mentioned mapped EST-RFLP markers and sequences of 8,470 publicly available A. stolonifera ESTs (AgEST). We discovered large-scale chromosomal rearrangements on six LGs of creeping bentgrass relative to B. distachyon. Also, a total of 24 syntenic blocks based on 678 orthologus loci were identified between these two grass species. The EST orthologs can be utilized in further comparative mapping of Pooideae species. These results will be useful for genetic improvement of Agrostis species and will provide a better understanding of evolution within Pooideae species.
Belonolaimus longicaudatus has been reported as damaging both potato (Solanum tuberosum) and cotton (Gossypium hirsutum). These crops are not normally grown in cropping systems together in areas where the soil is infested with B. longicaudatus. During the 1990s cotton was grown in a potato production region that was a suitable habitat for B. longicaudatus. It was not known how integrating the production of these two crops by rotation or double-cropping would affect the population densities of B. longicaudatus, other plant-parasitic nematodes common in the region, or crop yields. A 3-year field study evaluated the viability of both crops in monocropping, rotation, and double-cropping systems. Viability was evaluated using effects on population densities of plant-parasitic nematodes and yields. Rotation of cotton with potato was found to decrease population densities of B. longicaudatus and Meloidogyne incognita in comparison with continuous potato. Population densities of B. longicaudatus following double-cropping were greater than following continuous cotton. Yields of both potato and cotton in rotation were equivalent to either crop in monocropping. Yields of both crops were lower following double-cropping when nematicides were not used.
Belonolaimus longicaudatus; cotton; crop rotation; cropping system; double-cropping; Gossypium hirsutum; Meloidogyne incognita; nematode; potato; root-knot nematode; Solanum tuberosum; sting nematode
Attachment of relatively low numbers of endospores from two isolates of Pasteuria spp. to several species of nematodes was consistently achieved in 2-5 minutes with a centrifugation technique. The rate of attachment of Pasteuria penetrans at 10⁴ endospores/0.1 ml/tube to second-stage juveniles (J2) of Meloidogyne javanica, M. incognita race 1, M. incognita race 3, and M. arenaria races 1 and 2 in two tests averaged 4.4, 5.2, 0.1, 0.3, and 0 endospores per J2, respectively. The rate of attachment Pasteuria sp. at 10³ endospores/0.1 ml/tube to individuals of Hoplolaimus galeatus, Belonolaimus longicaudatus, M. arenaria race 1, M. javanica, and M. incognita race 1 in two tests averaged 0.8, 0.04, 0, 0, and 0 endospores per nematode, respectively. The rate of attachment of P. penetrans to M. javanica at 10³, 10⁴, or 10⁵ endospores/0.1 ml/tube from two tests averaged 1.0, 5.7, and 28.3 endospores per J2, respectively. All of the J2 had endospores attached following centrifugation in tubes with 10⁴ and 10⁵ endospores/0.1 ml/tube.
bacterium; biological control; centrifugation; endospore; Meloidogyne arenaria; M. incognita; M. javanica; method; nematode; Pasteuria penetrans; Pasteuria sp.
Interaction of Belonolaimus longicaudatus, Meloidogyne incognita, and Pratylenchus brachyurus on corn and B. longicaudatus, M. incognita, and Heterodera glycines on soybean was investigated in micropiots during two seasons for corn and one season for soybean. Changes in population densities and effects on plant growth of each nematode on corn or soybean alone and in mixed culture were compared. No interactions occurred on corn in 1987. In 1988, midseason population densities of B. longicaudatus were greater in corn plots infested with M. incognita (P ≤ 0.05), but at harvest, population densities or B. longicaudatus were less in corn plots infested with P. brachyurus (P ≤ 0.05). Except for stalk weight at harvest, plant growth was not affected by any treatment. In soybean, midseason densities of M. incognita were increased in combination with H. glycines (P ≤ 0.05), but this trend reversed at harvest. Soybean yield was reduced in plots infested with H. glycines (P ≤ 0.001), whereas B. longicaudatus or M. incognita had no effect on plant growth either singly or in mixed culture.
Belonolaimus longicaudatus; corn; Glycine max; Heterodera glycines; interaction; Meloidogyne incognita; Pratylenchus brachyurus; soybean; Zea mays
Rooted cuttings of 'Iceberg' chrysanthemum in steamed soil were inoculated with the nematodes Belonolaimus longicaudatus, and Meloidogyne incognita, alone and combined with Pythium aphanidermatum, a fungus pathogen of chrysanthemum. B. longicaudatus alone severely restricted the root system; with P. aphanidermatum also present, plant weight and height were further reduced and onset of symptoms was earlier. M. incognita + fungus interaction was similar but less intense. The fungus suppressed egg production of M. incognita but not the reproduction of B. Iongicaudatus. However, all three pathogens combined significantly suppressed reproduction of both nematodes and caused greatest inhibition of plant growth.
Meloidogyne incognita; Belonolaimus longicaudatus; Pythium aphanidermatum; Chrysanthemum; Pathogenicity; Fungus-nematode interactions
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
Seasonal fluctuations in field populations of Meloidogyne spp. (M. incognita and M. hapla), Pratylenchus zeae, Criconemoides ornatum, Tylenchorhynchus claytoni, Belonolaimus longicaudatus, and Helicotylenchus dihystera were determined monthly for 1 year by three extraction procedures. Baermann funnel method (BF) gave highest recoveries of Meloidogyne spp. and P. zeae during summer and fall, but centrifugal-flotation (CF) and sugar-flotation-sieving (SFS) usually yielded higher numbers of these nematodes during winter and spring. CF was t h e only effective method for recovery of C. ornatum with maximum numbers occurring in September. Recoveries of T. claytoni were similar with all methods in summer and fall. However, BF gave low numbers in winter and spring, whereas population peaks with the flotation methods occurred in January and February. All methods gave similar recoveries of B. longicaudatus with highest numbers occurring in November and December. This species declined drastically in late winter and spring. Yields of H. dihystera were similar for all three methods with CF consistently higher and the major peaks occurring in August.
Meloidogyne incognita, Hoplolaintus galeatus, and North Carolina and Georgia populations of Belonolaimus longicaudatus were introduced singly and in various combinations with Fusarium oxysporum f. sp. vasinfectum on wilt-susceptible 'Rowden' cotton. Of all the nematodes, the combination of the N. C. population of B. longicaudatus with Fusarium promoted greatest wilt development. H. galeatus had no effect on wilt. With Fusarium plus M. incognito or B. longicaudatus, high nematode levels promoted greater wilt than low levels. The combination of either population of B. longicaudatus with M. incognita and Fusarium induced greater wilt development than comparable inoculum densities of either nematode alone or where H. galeatus was substituted for either of these nematodes. Nematode reproduction was inversely related to wilt development. Without Fusarium, however, the high inoculum level resulted in greater reproduction of all nematode species on cotton. Combining M. incognita with B. longicaudatus or H. galeatus gave mutually depressive effects on final nematode populations. The interactions of H. gateatus with B. longicaudatus varied with two populations of the latter.
Gossypium hirsutum; Meloidogyne incognito; Belonolaimus longicaudatus and Hoplolaimus galeatus
Growing cotton in a greenhouse with 12-h of supplemental light [8,608 lux (800 ft-c) from combination of mercury and Lucalux® lamps] resulted in 2 × to > 3 × greater reproduction of Meloidogyne incognita and Belonolaimus longicaudatus as compared to natural light alone. Rate of increase of Hoplolaimus galeatus was affected little in this experiment. In a second experiment under controlled conditions in a phytotron, light source and intensity had greater influence on the reproduction of Heterodera glycines and Pratylenchus penetrans on soybean than on B. longicaudatus. Fluorescent plus incandescent and metal halide light sources resulted in the greatest nematode reproduction. Lucalux lamps resulted in much lower rates of nematode increase than other light sources. Rates of nematode increase on soybean under the different light sources in the phytotron generally were positively related to plant growth.
Gossypium hirsutum; Glycine max
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
The pathogenicity and interactions of Meloidogyne naasi, Pratylenchus penetrans, and Tylenchorhynchus agri on 'Toronto C-15' creeping bentgrass, Agrostis palustris, was studied in a long-term greenhouse experiment. Based on dry weights of roots and clippings, M. naasi alone and in all combinations with P. penetrans and T. agri was highly pathogenic to creeping bentgrass. P. penetrans and T. agri alone and in combination inhibited root growth but adversely affected top growth only when the two were co-inoculated. In combination, the effects of each species on top growth were additive, with M. naasi the dominant pathogen. Creeping bentgrass was an excellent host for M. naasi and T. agri, but a poor host for P. penetrans. T. agri inhibited population increase of M. naasi, indicating nematode-nematode competition, but neither T. agr/ nor P. penetrans was affected by any of the combinations.
Agrostis palustris; root-knot nematode; lesion nematode; stunt nematode; pathogenicity; population dynamics; nematode complexes
Greenhouse experiments were conducted in 15-cm-d pots of steamed Myakka fine sand to determine the host status and tolerance of common basil (Ocimum basilicum) to several important phytoparasitic nematodes in Florida. Populations of Meloidogyne incognita, Belonolaimus longicaudatus, and Pratylenchus scribneri increased and caused significant suppression of foliage and root growth during a 10-month period. The population of Paratrichodorus christiei increased and caused a significant reduction in foliage yield but did not reduce root growth. Dolichodorus heterocephalus also increased in number without affecting foliage yield or root growth. Basil was a poor host for Hoplolaimus galeatus and was not damaged by this nematode.
awl nematode; basil; Belonolaimus longicaudatus; Dolichodorus heterocephalus; Hoplolaimus galeatus; lance nematode; lesion nematode; Meloidogyne incognita; Ocimum basilicum; Paratrichodorus christiei; Pratylenchus scribneri; root-knot nematode; sting nematode; stubby-root nematode
A number of highly reactive oxygen species have been implicated in the oxygen-dependent mechanisms involved in bactericidal activity of phagocytic leukocytes. Hydrogen peroxide and superoxide, two agents known to occur during phagocytosis, are thought to interact to generate hydroxyl radical, singlet oxygen, and other potentially reactive molecules. Using an assay system of ethylene generation from methional, cell preparations of human monocytes were demonstrated to generate hydroxyl radical or a similar agent during phagocytosis of zymosan particles. The generation of ethylene was impaired by agents which reduce superoxide or hydrogen peroxide concentrations as well as by agents reported to be hydroxyl radical scavengers. The ethylene generation did not appear to be dependent on myeloperoxidase in that azide enhanced ethylene generation. Monocytes from a patient with chronic granulomatous disease failed to generate ethylene during phagocytosis. This assay technique may be useful in exploring the metabolic events integral to the bactericidal and inflammatory activity of phagocytic leukocytes.
Stimulated human alveolar macrophages were demonstrated to oxidize B-methyl proprionaldehyde (methional) or 2-keto-4-thiomethylbutyric acid to ethylene (C2H4). Agents which are believed to scavenge the hydroxyl radical (.OH), sodium benzoate, and mannitol, as well as scavengers of superoxide anion (O2-) or hydrogen peroxide, decreased C2H4 production, implicaing .OH as the oxidizing radical. Differences in C2H4 rpoduction, as well as oxygen uptake and O2- release between human alveolar macrophages and polymorphonuclear leukocytes, were also documented.
Relationships between nematode density and yield and between final and preplant population levels were examined in small maize plots on sandy soils in north-central Florida. Plant-parasitic nematodes present in the community included Belonolaimus longicaudatus, Criconemella sphaerocephala, Meloidogyne incognita, Paratrichodorus minor, Pratylenchus brachyurus, and a Xiphinema sp. Plant growth--including stand count, grain yield, stalk weight, and size of young plants--often was inversely correlated (P ≤ 0.05) with densities of B. longicaudatus and occasionally with P. brachyurus, but not with densities of other species or with a range of soil variables. More severe losses in grain yields from B. longicaudatus occurred in 1987 than in 1988, although mean preplant nematode densities in February were similar in both years (4.4 vs. 3.9/100 cm³ soil). Final population densities of most nematode species were linearly related (P ≤ 0.05) to densities measured at planting or earlier. These relationships were stronger (higher r²) with the ectoparasites B. longicaudatus and C. sphaerocephala than with the endoparasites M. incognita and P. brachyurus. No significant correlations were found between population densities of different nematode species.
Belonolaimus longicaudatus; corn; Criconemella sphaerocephala; damage function; lesion nematode; maize; Meloidogyne incognita; nematode community; population dynamics; Pratylenchus brachyurus; ring nematode; root-knot nematode; sting nematode; Zea mays
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
A 2-year field study evaluated the influence of subsoiling and nematicide application, alone and in combination, on the growth and yield of field corn in a sandy soil in north-central Florida. The field had a 25-30-cm-deep tillage pan (plowpan) and was infested with Belonolaimus longicaudatus, Hoplolaimus galeatus, Trichodorus christei, and Pratylenchus spp. Subsoiling increased corn yield both years, and the residual effect of subsoiling in the first year increased yields in the second year. Preplant application of DD injected in-row increased yields and reduced nematode populations. At-planting applications of DD injected in-row and carbofuran in-furrow or in a band were less effective than subsoiling in increasing yields and reducing nematode numbers. Interactions between subsoiling and nematicide treatments occurred in the second year.
Belonolaimus longicaudatus (sting); Hoplolaimus galeatus (lance); Pratylenchus spp. (lesion); Trichodorus christei (stubby-root); carbofuran; chemical control; DD; tillage pan
Belonolaimus longicaudatus is a recognized pathogen of cotton (Gossypium hirsutum), but insufficient information is available on the population dynamics and economic thresholds of B. longicaudatus in cotton production. In this study, data collected from a field in Florida were used to develop models predicting population increases of B. longicaudatus on cotton and population declines under clean fallow. Population densities of B. longicaudatus increased on cotton, reaching a carrying capacity of 139 nematodes/130 cm³ of soil, but decreased exponentially during periods of bare fallow. The model indicated that population densities should decrease each year of monocropped cotton, if an alternate host is not present between sequential cotton crops. Economic thresholds derived from published damage functions and current prices for cotton and nematicides varied from 2 to 5 B. longicaudatus/130 cm³ of soil, depending on the nematicide used.
Belonolaimus longicaudatus; cotton; economic threshold; fallow; Gossypium hirsutum; modeling; nematode; population decline; population dynamics; population increase; sting nematode