Population Fluctuations of Three Nematode Genera in Putting Greens in Northern Illinois

Field experiments were conducted in 1989 and 1990 to examine the population fluctuation patterns of Tylenchorhynchus nudus, Criconemella curvata, and Helicotylenchus cornurus in mixed bentgrass and annual bluegrass putting greens on two golf courses near Chicago, Illinois, to determine if fluctuation patterns could be extrapolated to unsampled greens. Fenamiphos-treated and untreated plots were established on seven putting greens on two golf courses. Greens were sampled intensively five times during the growing season, and statistical comparisons of population levels per gram of root were made among dates for each green. Population levels per gram of root changed significantly on all greens in both years for each of the three nematode populations. Within a putting green in either year, population fluctuation patterns in fenamiphos-treated and untreated plots were similar. Population fluctuation patterns were different between years, however. Within a year, population fluctuation patterns among greens showed similarities indicating that carefully monitoring a few locations may allow extrapolation of population fluctuation data to other locations within that year.     

Criconemella spp. in Pennsylvania Peach Orchards with Morphological Observations of C. curvata and C. ornata

Criconemella xenoplax and C. curvata, previously associated with decline of peach trees in other parts of the United States, were found in 20 of 25 Pennsylvania peach orchards. Population densities were high in some samples. Morphometrics of juveniles and adult females of Criconemella curvata and C. ornata, are provided. Cuticular crenations were observed on J2 and J3 stages of C. curvata and J2-J4 stages of C. ornata.     

Population Response to Temperature in the Subfamily Tylenchorhynchinae

The effects of temperature on population development of 11 species of stunt nematodes in the subfamily Tylenchorhynchinae were compared on red clover or Kentucky bluegrass in constant-temperature tanks at 5-degree intervals from 10 to 35 C. The optimum temperature for population increase on red clover in 90 days was 30 C for Tylenchorhynchus agri, T. nudus, T. martini, and T. clarus, 25 C for T. sylvaticus and T. dubius, and 20 C for T. canalis, Merlinius brevidens, and Quinisulcius capitatus. The optimum was 30 C for T. robustoides and 25 C for T. maximus on Kentucky bluegrass. The temperature range for population increase was 20-35 C for T. agri, T. nudus, T. martini, and T. clarus, 20-30 C for T. sylvaticus and T. robustoides, 15-25 C for T. maximus, 10-25 C for T. dubius, and 10-20 C for M. brevidens and Q. capitatus. T. canalis increased only at 20 C. All species were recovered in numbers near their inoculum level at 10 C. There was no survival of T. sylvaticus, T. dubius, T. canalis, T. robustoides, T. maximus, M. brevidens, and Q. capitatus at 35 C, or of the last three of these species at 30 C. Temperature had no effect on sex ratio in final populations. Population increase was greatest in T. martini and least in T. canalis.     

Root Growth of Bentgrass and Annual Bluegrass as Influenced by Coinfection with Tylenchorhynchus nudus and Magnaporthe poae

A study was conducted in growth chambers to examine main factor and interaction effects of Tylenchorhynchus nudus and Magnaporthe poae on creeping bentgrass and annual bluegrass at 24, 28, and 30 C. A 2 x 2 factorial arrangement of treatments was employed with presence and absence of T. nudus and M. poae as factors with each temperature run separately for 14 or 18 days. Tylenchorhynchus nudus decreased bentgrass and annual bluegrass root length at all three temperatures. Magnaporthe poae had no effect on bentgrass root length at 24 C, increased root length at 28 C, and suppressed root growth at 30 C. Magnaporthe poae had no effect on annual bluegrass root length at 24 and 28 C but suppressed root growth at 30 C. A significant interaction between M. poae and T. nudus occurred only on bentgrass at 28 C and 30 C; at these two temperatures, M. poae did not act independently of T. nudus.     

Nematicide Efficacy,Root Growth,and Fruit Yield in Drip-irrigated Pineapple Parasitized by Rotylenchulus reniformis

A 3-year field trial near Kunia, Oahu, Hawaii, was conducted to evaluate four nematicide treatments for efficacy against Rotylenchulus reniformis in drip-irrigated pineapple (Ananas comosus L. (Merr.)). The treatments were (A) preplant fumigation with 1,3-dichloropropene (1,3-D) (336 liter/ ha) and postplant drip application of fenamiphos (3.4 kg/ha) with restricted irrigation, (B) preplant 1,3-D only, weekly irrigation, (C) 1,3-D fenamiphos, weekly irrigation, and (D) postplant fenamiphos only, weekly irrigation. Fenamiphos was applied at 3-month intervals for 1 year after planting in three treatments. Although nematode populations increased in all treatments 1 year after planting, no differences in fruit yield were detected among treatments in the first (plant crop) harvest 19 months after planting. In the second (ratoon) crop (33 months after planting) significant yield differences, larger fruit size, and greater root biomass were obtained in the dual nematicide treatments. Root biomass increased continuously throughout the crop cycle, was greatest near the drip line, and showed a shallow depth distribution (30-40 cm). Rotylenchulus reniformis populations and fenamiphos concentrations were negatively correlated in soil profiles taken 13 months after planting. In the absence of postplant fenamiphos applications, nematode numbers were positively correlated with root biomass.     

Root-knot Nematode Problem of Some Winter Ornamental Plants and Its Biomanagement

A microplot study under field conditions was carried out during 2 consecutive years to assess the effect of root-knot nematode infection (2,000 Meloidogyne incognita eggs/kg soil) on three winter ornamental plants: hollyhock (Althea rosea), petunia (Petunia hybrida), and poppy (Papaver rhoeas). Effects of root-dip treatment with the biocontrol agents Pochonia chlamydosporia, Bacillus subtilis, and Pseudomonas fluorescens and the nematicide fenamiphos were tested. The three ornamental species were highly susceptible to M. incognita, developing 397 and 285 (hollyhock), 191 and 149 (petunia), and 155 and 131 (poppy) galls and egg masses per root system, respectively, and exhibited 37% (petunia), 29% (poppy), and 23% (hollyhock) (P = 0.05) decrease in the flower production. Application of fenamiphos, P. chlamydosporia, P. fluorescens, and B. subtilis suppressed nematode pathogenesis (galls + egg masses) by 64%, 37%, 27%, and 24%, respectively, leading to 14% to 29%, 7% to 15%, 14% to 36%, and 7% to 33% increase in the flower production of the ornamental plants, respectively. Treatment with P. fluorescens also increased the flowering of uninfected plants by 11% to 19%. Soil population of M. incognita was decreased (P = 0.05) due to various treatments from 2 months onward, being greatest with fenamiphos, followed by P. chlamydosporia, B. subtilis, and P. fluorescens. Frequency of colonization of eggs, egg masses, and females by the bioagents was greatest by P. chlamydosporia, i.e., 25% to 29%, 47% to 60%, and 36% to 41%, respectively. Colonization of egg masses by B. subtilis and P. fluorescens was 28% to 31% and 11% to 13%, respectively, but the frequency was 0.3% to 1.3% in eggs. Rhizosphere population of the bioagents was increased (P = 0.05) over time, being usually greater in the presence of nematode.     

In Vitro Parasitism of Rotylenchus robustus by Isolates of Hirsutella rhossiliensis

We tested the hypothesis that isolates of Hirsutella rhossiliensis from host nematodes in the family Hoplolaimidae (Rotylenchus robustus and Hoplolaimus galeatus) would be more virulent to R. robustus than would isolates from host nematodes not in the Hoplolaimidae (Heterodera schachtii and Criconemella xenoplax). Nematodes were touched to 10-20 spores of different isolates and incubated at 20 C in 4.5 mM KC1; the percentage of nematodes colonized (filled with hyphae) was determined after 2, 5, 10, 20, and 30 days. The hypothesis was rejected because isolates from H. schachtii and C. xenoplax were equivalent or better at parasitizing R. robustus than were isolates from R. robustus and H. galeatus. In addition, the R. robustus and H. galeatus isolates were as pathogenic to C. curvata as they were to R. robustus, but produced fewer spores per colonized nematode (H. schachtii) than did the other isolates.     

Population Dynamics of Meloidogyne incognita,M. arenaria,and Other Nematodes and Crop Yields in Rotations of Cotton,Peanut, and Wheat Under Minimum Tillage

Wheat, cotton, and peanut were arranged in three cropping sequences to determine the effects of fenamiphos (6.7 kg a.i./ha) and cropping sequence on nematode population densities and crop yields under conservation tillage and irrigation for 6 years. The cropping sequences included a wheat winter cover crop each year and summer crops of cotton every year, peanut every year, or cotton rotated every other year with peanut. The population densities of Meloidogyne spp. and Helicotylenchus dihystera were determined monthly during the experiment. Numbers of M. incognita increased on cotton and decreased on peanut, whereas M. arenaria increased on peanut, and decreased on cotton; both nematode species remained in moderate to high numbers in plots of wheat. Root damage was more severe on cotton than peanut and was not affected by fenamiphos treatment. The H. dihystera population densities were highest in plots with cotton every summer, intermediate in the cotton-peanut rotation, and lowest in plots with peanut every summer. Over all years and cropping sequences, yield increases in fenamiphos treatment over untreated control were 9% for wheat, 8% for cotton, and 0% for peanut. Peanut yields following cotton were generally higher than yields following peanut. These results show that nematode problems may be manageable in cotton and peanut production under conservation tillage and irrigation in the southeastern United States.     

Crop Yields and Nematode Population Densities in Triticale-Cotton and Triticale-Soybean Rotations

Triticale cv. Beagle 82, cotton cv. McNair 235, and soybean cv. Twiggs were arranged in three cropping sequences to determine the effects of fenamiphos and cropping sequence on nematode population densities and crop yields under conservation tillage for 4 years. The cropping sequences were triticale (T)-cotton (C)-T-C, T-soybean (S)-T-S, and T-C-T-S. Numbers of Meloidogyne incognita second-stage juveniles declined on trificale but increased on cotton and soybean each year. Root-gall indices of cotton and soybean ranged from 1.00 to 1.08 (1 to 5 scale: 1 = 0%, 2 = 1% to 25%, 3 = 26% to 50%, 4 = 51% to 75%, and 5 = 76% to 100% of roots galled) each year and were not affected by fenamiphos treatment or cropping sequence. Numbers of Pratylenchus brachyurus were maintained on trificale and generally increased more on soybean than on cotton. Population densities of Helicotylenchus dihystera were near or below detection levels in all plots during the first year and increased thereafter in untreated plots in the T-C-T-C and T-S-T-S sequences. Generally, yields of triticale in all cropping sequences declined over the years. Yields of cotton and soybean were not affected by fenamiphos at 6.7 kg a.i./ha. Cotton and soybean were grown successfully with little or no suppression in yields caused by nematodes in conservation tillage following triticale harvested for grain.     

Nematode Numbers and Crop Yield in a Fenamiphos-Treated Sweet Corn-Sweet Potato-Vetch Cropping System

Nematode population densities and yield of sweet corn and sweet potato as affected by the nematicide fenamiphos, in a sweet corn-sweet potato-vetch cropping system, were determined in a 5-year test (1981-85). Sweet potato was the best host of Meloidogyne incognita of these three crops. Fenamiphos 15G (6.7 kg a.i./ha) incorporated broadcast in the top 15 cm of the soil layer before planting of each crop increased (P ≤ 0.05) yields of sweet corn in 1981 and 1982 and sweet potato number 1 grade in 1982 and 1983. Yield of sweet corn and numbers of M. incognita second-stage juveniles (J2) in the soil each month were negatively correlated from planting (r = - 0.47) to harvest (r = -0.61) in 1982. Yield of number 1 sweet potato was inversely related to numbers of J2 in the soil in July-October 1982 and July-September 1983. Yield of cracked storage roots was positively related to the numbers of J2 in the soil on one or more sampling dates in all years except 1985. Some factor(s), such as microbial degradation, resistant M. incognita development, or environment, reduced the effect of fenamiphos.     

Temperature Effects on Heterorhabditis megidis and Steinernema carpocapsae Infectivity to Galleria mellonella

The effect of temperature on the infection of larvae of the greater wax moth, Galleria mellonella, by Heterorhabditis megidis H90 and Steinernema carpocapsae strain All, was determined. For both species, infection, reproduction, and development were fastest at 20 to 24 °C. Infection by both H. megidis and S. carpocapsae occurred between 8 and 16 °C; however, neither species reproduced at 8 °C. Among the nematodes used in experiments at 8 °C, no H. megidis and very few S. carpocapsae developed beyond the infective juvenile stage. Compared with H. megidis, S. carpocapsae invaded and killed G. mellonella larvae faster at 8 to 16 °C. By comparing invasion rates, differences in infectivity between the two nematode species were detected that could not be detected in conventional petri dish bioassays where mortality was measured after a specified period. Invasion of G. mellonella larvae by H. megidis was faster at 24 than at 16 °C.     

Control of Globodera tabacum solanacearum by Alternating Host Resistance and Nematicide

The feasibility of alternating use of resistant vs. susceptible flue-cured tobacco cultivars to improve control of Globodera tabacum subsp, solanacearum (TCN) was investigated at two Virginia locations in 1984-86. Post-harvest TCN population densities were reduced in each year of the study when fenamiphos was used with a TCN-resistant cultivar (NC 567), relative to susceptible cultivars (K 326 or Mc 944). Using NC 567 with fenamipbos also reduced preplant TCN population densities in the next growing season. Egg population densities before planting in 1986 were significantly lower in plots planted with NC 567 in 1984, even when a susceptible cultivar had been planted in 1985. Use of fenamiphos with NC 567 in 1984 and 1985 further reduced preplant egg population densities in 1986. Economic returns were significantly greater in 1984 when NC 567 was used with fenamiphos, rather than a susceptible cultivar. Treatments involving fenamiphos and (or) NC 567 in 1984 and 1985 resulted in higher economic returns in 1986 than did treatments using a susceptible cultivar without fenamiphos in both previous years. Economic returns were highest in 1986 when fenamiphos and NC 567 were used in 1984 and 1985 and a susceptible cultivar was planted in 1986.     

Cuticle Ultrastructure of Criconemella curvata and Criconemella sphaerocephala (Nemata: Criconematidae)

Cuticle ultrastructure of Criconemella curvata and C. sphaerocephala females is presented; males were available only in the second species. Ultrathin sections revealed three major zones: cortical, median, and basal. The cortical zone in the females consists of an external and internal layer. In C. curvata the external layer is trilaminate and at each annule it is covered by a multilayered cap. In C. sphaerocephala the trilaminate layer is lacking and the external cortical layer includes an osmophilic coating. In both species the internal layer consists of alternate striated and unstriated sublayers. The median zone is fibrous with a central lacuna and the zone is interrupted between the annules. The basal zone of the cuticle is striated and narrower between each annule. The cuticle of the C. sphaerocephala male is typical of Tylenchida, except under both lateral fields; the striated layer becomes forked at the first incisure and the innermost two prongs of the fork overlap each other, resulting in a continuous striated band.     

Fishborne Trematode Metacercariae Detected in Freshwater Fish from Vientiane Municipality and Savannakhet Province, Lao PDR

Freshwater fish from Vientiane Municipality and Savannakhet Province, Lao PDR were examined by the muscle compression and artificial digestion methods to know the infection status with trematode metacercariae. In the fish from Savannakhet, 2 species of metacercariae, Opisthorchis viverrini and Haplorchis taichui, were detected. O. viverrini metacercariae were found in 6 species of fish, Puntius brevis, Hampala dispar, Esomus metallicus, Mystacoleucus marginatus, Puntioplites falcifer, and Cyclocheilichthys armatus. H. taichui metacercariae were detected in 3 species of fish, P. brevis, P. falcifer, and M. marginatus. In the fish from Vientiane, 4 species of metacercariae, O. viverrini, H. taichui, Haplorchis yokogawai, and Centrocestus formosanus, were detected. Among them, O. viverrini metacercariae were found in 7 species of fish, Onychostoma elongatum, C. armatus, H. dispar, P. brevis, Cyclocheilichthys repasson, Osteochilus hasseltii, and Hypsibarbus lagleri. The metacercariae of H. taichui were detected in 6 species of fish, C. repasson, O. elongatum, C. armatus, H. dispar, Labiobarbus leptocheila, and Cirrhinus molitorella. The metacercariae of H. yokogawai were found in 9 species of fish, C. repasson, O. elongatum, C. armatus, H. dispar, Labiobarbus leptocheila, O. hasseltii. C. molitorella, Hypsibarbus wetmorei, and H. lagleri. The metacercariae of C. formosanus were detected in 4 species of fish, C. repasson, P. brevis, O. hasseltii, and C. molitorella. From these results, it is confirmed that fishborne trematode metacercariae, i.e. O. viverrini, H. taichui, H. yokogawai and C. formosanus, are prevalent in various species of freshwater fish from Savannakhet Province and Vientiane Municipality, Lao PDR.     

Development of Heterodera glycines as Affected by Alachlor and Fenamiphos

A series of greenhouse experiments was conducted to elucidate the postinfection development of Heterodera glycines in response to applications of alachlor and fenamiphos. The rate of H. glycines maturation on a susceptible soybean cultivar was not altered by 1.0 μg alachlor/g soil but was completely inhibited by 1.0 or 1.5 μg fenamiphos/g soil. An alachlor-fenamiphos combination allowed development after an initial 300-degree-day delay. Nematode maturation on the resistant soybean cultivar Centennial with 1.0 μg alachlor/g soil was similar to that observed on an untreated resistant control. Twice as many females matured on Centennial plants growing in alachlor-treated soil as on untreated Centennial plants. Fenamiphos in combination with alachlor (1.0 μg a.i./g soil) allowed development on Centennial at half the rate of the resistant control. This antagonism between alachlor and fenamiphos on development may help to explain late season population resurgence of H. glycines observed with field application of these pesticides.     

Effects of Nematicides on Nematode Densities in Turf in Connecticut

The plant-parasitic nematodes Criconemoides lobatum, Hoplolaimus tylenchiformis, and Tylenchorhynchus dubius were present in the top 7.5 cm of sod consisting of numerous stolons and fibrous roots. Phenamiphos and 1,2-dibromo-3-chloropropane (DBCP) controlled all three species, whereas ethoprop and oxamyl controlled H. tylenchiformis and T. dubius but not C. lobatum. Benomyl and carbofuran controlled H. tylenchiformis but had poor control of C. lobatum and T. dubius. The effectiveness of carbofuran varied with the type of formulation, being most effective as a quick-release formulation. C. lobatum was the most difficult to control with chemicals. No chemical treatment improved the growth of ''Astoria colonial'' bentgrass (A. tenuis Sibth.) or Kentucky bluegrass (Poa pratensis L.) under the moist condtions prevalent in these tests.     

Vertical Distribution of Plant-parasitic Nematodes in Sandy Soil under Soybean

Vertical distribution of five plant-parasitic nematodes was examined in two north Florida soybean fields in 1987 and 1988. Soil samples were collected from 0-15 cm, 15-30 cm, and 30-45 cm deep at each site. Soil at the three depths consisted of approximately 96% sand. More than 50% of Belonolaimus longicaudatus population densities occurred in the upper 15-cm soil layer at planting, but the species became more evenly distributed through the other depths as the season progressed. Criconemella sphaerocephala was evenly distributed among the three depths in one field but was low (< 20% of the total density) in the upper 15 cm at a second site. Maximum population densities of Pratylenchus brachyurus were observed at 15-30 cm on most sampling dates. Vertical distributions of Meloidogyne incognita and Paratrichodorus minor were erratic and showed seasonal variation. A diagnostic sample from the upper 0-15 cm of these soybean fields revealed only a minority of the populations of most of the phytoparasitic species present.     

Characterization of Sialyl and Galactosyl Residues on the Body Wall of Different Plant Parasitic Nematodes

The plant parasitic nematodes Helicotylenchus multicinctus, Meloidogyne javanica, Tylenchulus semipenetrans, and Xiphinema index, differing in their host specificity and parasitic habits, were analyzed as to their cuticle surface sialyl, galaclosyl, and/or N-acetylgalactosaminyl residues. The procedure involved the selective oxidation of sialic acid and galactose/N-acetylgal-actosamine residues using periodate and galactose oxidase, respectively, to form reactive aldehyde groups. These functional groups were coupled directly with a new hydrazide-containing compound, the fluorescent reagent lissamine rhodamine-β-alanine hydrazide, or they were utilized to introduce DPN-groups to the nematode cuticle. The distribution of the DNP-tagged glycoconjugates was visualized by treating the nematodes with rabbit anti-DNP antibody and staining with fluorescein isothiocyanate (FITC)-labeled goat antirabbit IgG. Sialo residues were observed along the entire outer body wall of the first three aforementioned nematodes, but there were some differences in reaction among the various life stages within the species. In X. index, sialo residues were sited in the tail and head areas, mainly on the lips, oral opening, amphid apertures and stylet. Galactose oxidase treatments revealed galactose on N-acytylgalactosamine residues on T. sentipenetrans and X. index, but there were no indications that their presence was dependent on the developmental stage. Trypsin, pronase, and neuraminidase pretreatment completely abolished the fluorescence in T. semipenetrans but did not alter the sialo residue binding reaction in H. multicinctus or M. javanica, indicating possible differences in the outer body wall saccharide structure and composition between these nematodes. The existence and nature of sugar residues on the cuticle surface of nematodes could contribute to an understanding of the specific recognition by phytophagous nematodes of their host, and perhaps also of the virus transmission mechanism in those nematodes which serve as vectors.     

Relationship between Cultural Factors and Nematodes on Merion Kentucky Bluegrass

A 2-year study was conducted on Merion Kentucky bluegrass turf (Poa pratensis) to identify potential relationships among seasonal population dynamics of nematodes, chemical applications, thatch, tillering, dollar spot caused by Sclerotinia homoeocarpa, clipping weight, and other factors. Numbers of Tylenchorhynchus maximus determined during June were inversely related to the wet weight of grass from May. One or more monthly counts of Paratylenchus hamatus, Criconemella rusium, and T. maximus negatively correlated with the numbers of spring tillers. Applications of benomyl, used for dollar spot control, decreased numbers of T. maximus and free-living nematodes, and this chemical was associated with acidification of the thatch. Hoplolaimus galeatus levels were associated with an estimated 8% increase in the severity of dollar spot.     

Fishborne Trematode Metacercariae in Freshwater Fish from Guangxi Zhuang Autonomous Region, China

A survey was performed to investigate the infection status of fishborne trematode (FBT) metacercariae in freshwater fish from Guangxi Zhuang Autonomous Region, China. A total of 307 freshwater fish of 31 species were collected from 5 administrative regions of Guangxi Zhuang Autonomous Region. They were examined by artificial digestion method from July 2003 to August 2004. No metacercariae were detected in fish from Fusui-xian. In fish from Mashan-xian and a market in Nanning, 3 species of metacercariae, Haplorchis taichui, Haplorchis pumilio, and Centrocestus formosanus, were mainly detected. Metacercariae (8 in number) of Clonorchis sinensis were found in 1 Chanodichthys dabryi purchased from a market in Nanning. In fish from Yangshuo, Metagonimus yokogawai metacercariae were detected from all 18 fish species examined. Total 13 C. sinensis metacercariae were found in 3 out of 10 Hemibarbus maculatus from Yangshuo. All 7 Zacco platypus from Yangshuo were infected with 8-112 Echinochasmus perfoliatus metacercariae. In fish from Binyang-xian, H. pumilo metacercariae were mainly detected in all 5 fish species examined, and only 1 metacercaria of C. sinensis was found in a Hemiculter leucisculus. From the above results, it was confirmed that some species of freshwater fish play a role of second intermediate hosts for FBT in Guangxi Zhuang Autonomous Region, China. In particular, 4 species of intestinal flukes, M. yokogawai, H. taichui, H. pumilio, and C. formosanus, were prevalent in fish hosts, whereas C. sinensis metacercariae were detected only in 3 fish species.