Depth distribution of plant-parasitic nematodes on bentgrass golf greens in Missouri and Indiana.

Control of plant-parasitic nematodes (PPNs) on golf putting greens with nematicides is dependent on the seasonal occurrence and depth distribution of target PPN populations. This study aimed to determine if plant-parasitic nematode populations on golf course putting greens in Missouri and Indiana peaked at a targetable depth at a specific time in the year, focusing primarily on lance (Hoplolaimus spp.) and root-knot (Meloidogyne spp.) nematodes. To elucidate species diversity in the region, rDNA from a subset of lance and root-knot nematodes was sequenced and analyzed, with additional micromorphology of a lance nematode assessed in scanning electron micrographs (SEM). Soil samples were taken to a depth of 25 cm and stratified into 5 cm increments during April, June, August and October at seven sites across Missouri, three in the Kansas City metro of Kansas in 2021 and in ten sites across Indiana in 2022. Samples were stratified in five-centimeter increments and aggregated for a total of 100 cm3 of soil at each depth for each sampling. Samples were processed using a semi-automatic elutriator followed by the sucrose-flotation method, and populations were counted using a hemocytometer and recorded. For molecular characterization, rDNA was extracted and analyzed from 31 individual lance nematodes from one site in Missouri and eight sites in Indiana, and 13 root-knot nematodes from nine sites across Indiana. A significant interaction occurred between sampling month and depth for lance and ring nematodes Missouri/KS, with both PPN populations peaking at the 0-5 cm depth during October, which is well after most targeted nematicide applications are applied. Ring nematodes in Indiana did not follow this trend and were most abundant in August at a depth of 0-5 cm. No significant interaction between depth and month occurred for lance or root-knot nematodes in Indiana, or root-knot nematodes in Missouri/KS. Hoplolaimus stephanus and H. magnistylus were the lance species identified on golf greens, and Meloidogyne naasi, M. graminicola and M. marylandi were the root-knot species identified. Scanning-electron micrographs confirmed morphological characteristics unique to H. stephanus.

Saline Irrigation Affects Belonolaimus longicaudatus and Hoplolaimus galeatus on Seashore Paspalum.

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 (r(2) = 0.92 and 0.83; P <= 0.01) with increasing salinity levels. Final population densities of B. longicaudatus were quadratically (r(2) = 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.

Alternatives to fenamiphos for management of plant-parasitic nematodes on bermudagrass.

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

Host Status of 'SeaIsle 1' Seashore Paspalum (Paspalum vaginatum) to Belonolaimus longicaudatus and Hoplolaimus galeatus.

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

Effect of Carbon Amendment and Soil Moisture on Tylenchorhynchus spp. and Hoplolaimus galeatus.

The effect of amending soil held at 3 different moisture levels with glucose, unsulfured molasses, or nutrient broth (0.3, 0.7, 3.2, 7.1 g carbon/100 g) on Tylenchorhynchus claytoni and T. dubius was investigated. When soil was held under saturated or flooded conditions in the absence of carbon amendments for 7 days, Tylenchorhynchus populations were 19% and 16%, respectively, of the controls. Carbon amendments at all levels tested precipitated a further decline in the nematode population to 1% or less of the unamended controls in 7 days. Two applications of molasses (7.4%, w/w) 3 days apart to nematode-infested soil held in Conetainers under mist for 7 days reduced Tylenchorhynchus spp. and Hoplolaimus galeatus densities to 7% and 3%, respectively, of the controls. Nematode densities in turfgrass field plots also declined following irrigation and repeated drenching with a molasses solution. Based on the observed decline in redox potential and pH in saturated soil, especially following carbon amendment, we propose that the activity of anaerobic fermentative bacteria was responsible for the reduction in nematode densities.

Survey of crop losses in response to phytoparasitic nematodes in the United States for 1994.

Previous reports of crop losses to plant-parasitic nematodes have relied on published results of survey data based on certain commodities, including tobacco, peanuts, cotton, and soybean. Reports on crop-loss assessment by land-grant universities and many commodity groups generally are no longer available, with the exception of the University of Georgia, the Beltwide Cotton Conference, and selected groups concerned with soybean. The Society of Nematologists Extension Committee contacted extension personnel in 49 U.S. states for information on estimated crop losses caused by plant-parasitic nematodes in major crops for the year 1994. Included in this paper are survey results from 35 states on various crops including corn, cotton, soybean, peanut, wheat, rice, sugarcane, sorghum, tobacco, numerous vegetable crops, fruit and nut crops, and golf greens. The data are reported systematically by state and include the estimated loss, hectarage of production, source of information, nematode species or taxon when available, and crop value. The major genera of phytoparasitic nematodes reported to cause crop losses were Heterodera, Hoplolaimus, Meloidogyne, Pratylenchus, Rotylenchulus, and Xiphinema.

Observations on a Pasteuria Isolate Parasitic on Hoplolaimus galeatus in Peru.

A Pasteuria isolate associated with a population of the lance nematode Hoplolaimus galeatus was discovered in Peru. The infective propagules adhered to adult stages and juveniles and were found filling the bodies of males and females. The endospore and central core diameters measured 4.5 +/- 0.4 pm and 1.9 +/- 0.2 mum, respectively, which differed from those reported for other Pasteuria isolates found iu North America on the same host. Examinations of endospore ultrastructure with scanning electron microscopy showed the presence of a thin layer of parasporal fibers surrounding the central core, a thin reduced layer of parasporal fibers in contact with the host's cuticle, and a putative basal core ring.

Survey of Heterodera glycines Races and Other Plant-parasitic Nematodes on Soybean in North Carolina.

A survey of soybean-production areas in the Piedmont, Coastal Plain and Tidewater regions of North Carolina was conducted from 1994 to 1996. Heterodera glycines was detected in 55 of 77 fields sampled in 15 counties. The host race of H. glycines was determined for 39 of the populations collected. Of all populations collected, 4% were race 1, 40% race 2, 16% race 4, 7% race 5, and 4% race 9; the remaining 29% could not be accurately categorized. None of the populations evaluated had high levels of reproduction on the resistant cultivar Hartwig. The southern root-knot nematode Meloidogyne incognita was detected in 26% of the fields. Helicotylenchus spp. were detected in all fields sampled, Tylenchorhynchus spp. were found in 62%, Paratrichodorus spp. in 56%, and Pratylenchus spp. in 72% of fields sampled. Mesocriconema spp., Xiphinema spp., and Hoplolaimus spp. were detected in less than 20% of the fields sampled.

High-pressure Liquid Injection of Isazofos for Management of Hoplolaimus galeatus and Tylenchorhynchus dubius Infesting Turfgrasses.

Three high-pressure liquid injection machines were used to inject isazofos into the root zone of tuff;grass plots to evaluate its potential for control of Hoplolaimus galeatus and Tylenchorhynchus dubius. A Rogers root zone injector delivering isazofos at 2.3 kg a.i./ha through 30 degrees and 60 degrees spray tips at 5,000 psi (3.45 x 10 Pascals) significantly reduced nematode populations at 32 days after a single application and 33 days after a second application. In a second experiment with the Rogers injector at 2.3 kg a.i./ha, H. galeatus populations were significantly lower at 16 days after a single application and at 42 and 61 days after a second application with the 60 degrees spray angle tips. An Envirojet turfgrass injector used to inject isazofos at 1.15 kg a.i./ha and 2.88 kg a.i./ha at 3,000 psi (1.38 x 107 Pascals) significantly reduced nematode populations at 7 days after treatment at the low rate and at 63 days after treatment with both application rates. A Landpride material injector applying isazofos at 6.9 and 13.8 kg a.i./ha at 2,000 psi (1.38 x 10 Pascals) significantly reduced nematode populations at 7, 14, and 63 days after treatment at the high rate and at 63 days after the low-rate application. Although suppression of nematodes with isazofos was found, the degree of suppression is probably not enough to warrant recommendation of high-pressure delivery of isazofos for control of H. galeatus and T. dubius populations infesting turfgrasses.

Avermectin B1, Isazofos, and Fenamiphos for Control of Hoplolaimus galeatus and Tylenchorhynchus dubius Infesting Poa annua.

Avermectin B, isazofos, and fenamiphos were evaluated in greenhouse experiments for efficacy against two common turfgrass parasites, Hoplolaimus galeatus and Tylenchorhynchus dubius. Treatments in all experiments were arranged in a completely randomized design and replicated four times. In the first experiment, avermectin B at rates of 0.2 and 0.4 kg a.i./ha and isazofos at rates of 2.3 and 23 kg a.i./ha significantly reduced populations of both species of parasitic nematodes compared to controls at 14 and 28 days after treatment (P

Parasitism of Hoplolaimus galeatus on Diploid and Polyploid St. Augustine grasses.

'Floratam' and 'FX-313' St. Augusfinegrasses (Stenotaphrum secundatum) were compared in a time-course experiment for host suitability and susceptibility to the lance nematode, Hoplolaimus galeatus. Nematode densities were determined in the soil and acid-fuchsin stained roots 42, 84, 126, 168, and 210 days after pots containing 230 cm(3) of autoclaved native Margate fine sand/pot were infested with 104 +/- 9 nematodes and maintained at 25 +/- 2 C in the laboratory. 'FX-313' was a more suitable host for H. galeatus. Numbers of H. galeatus reached a maximum at 210 days after inoculation, with 5,550 and 4,120 nematodes (adults plus juveniles)/pot for 'FX-313' and 'Floratam,' respectively. Root and shoot dry weights of both grasses were not affected by H. galeatus throughout the experiment. Three polyploid, 2n = 30 to 32 ('Floratam,' 'FX-10,' and 'Bitterblue') and three diploid, 2n = 18 ('FX-313,' 'Florida Common,' and 'Seville') S. secundatum genotypes were inoculated with H. galeatus (99 +/- 9/pot) and compared with uninoculated controls 210 days after inoculation. St. Augustinegrass genotypes differed as hosts of H. galeatus. 'FX-313' and 'Florida Common' represented the high and low extremes, respectively, for nematode reproduction (9,750 and 5,490 nematodes/pot or 4,239 and 2,387 nematodes/100 cm(3) of soil). However, differences in root and shoot growth were not detected 210 days after inoculation with H. galeatus.

Survey of Plant-parasitic Nematodes in Missouri Cotton Fields.

During September 1990, 30 cotton fields in each of three Missouri counties were surveyed for plant-parasitic nematodes. Soil samples for nematode analysis consisted of a composite of 20 cores collected in a zig-zag pattern within a 1-ha block in each field. Cores were taken from within weed-free cotton rows. Nine genera of plant-parasitic nematodes were found (Rotylenchulus, Helicotylenchus, Hoplolaimus, Meloidogyne, Paratylenchus, Pratylenchus, Tylenchorhynchus, Heterodera, and Trichodorus), and five species were identified: Meloidogyne incognita, Rotylenchulus reniformis, Hoplolaimus galeatus, Pratylenchus vulnus, and P. scribneri. This is the first report of R. reniformis, H. galeatus, P. vulnus, and P. scribneri in Missouri cotton fields and the first report of R. reniformis and P. vulnus in Missouri. The known cotton pathogens M. incognita, R. reniformis, and H. galeatus were found in 30%, 3%, and 2% of the fields sampled, respectively. The correlation between sand content of the soil sample and the number of vermiform M. incognita in the sample was not significant, with r(2) = 0.13. Select fields where H. galeatus and R. reniformis were found in 1990 were sampled more intensely in 1991. The 1-ha block sampled in 1990 was sampled in 1991, along with three other 1-ha blocks uniformly distributed within the field. In addition, a 1-ha block was sampled in each of eight nearby fields, within 2 km of the first field. The nine plant-parasitic nematode genera identified in the 1990 survey were observed again in 1991. Within-field distribution of M. incognita, R. reniformis, and H. galeatus was not uniform. When M. incognita, R. reniformis, or H. galeatus were present in a field, the same species was found in 38%, 25%, or 50% of nearby fields, respectively.

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.

Specific Gravity of Spores of Pasteuria penetrans and Extraction of Spore-filled Nematodes from Soil.

The specific gravity of spores of Pasteuria penetrans collected from Meloidogyne arenaria was found to be around 1.28. Increasing the sucrose concentration used for the extraction of Pratylenchus scribneri from a specific gravity of 1.14 to 1.26 led to the recovery of higher numbers of specimens filled with spores of Pasteuria sp. (P

Isolates of the Pasteuria penetrans Group from Phytoparasitic Nematodes in Bermudagrass Turf.

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

Age structure and community diversity of nematodes associated with maize in iowa sandy soils.

Age structure of nematode populations around maize growing in sandy soils in Iowa was studied at soil depths of 0-15and 15-30 cm for 2 years. Numbers of Longidorus breviannulatus were generally greater at 0-15 cm than at 15-30 cm deep until mid to late season. The decline in numbers of females as the season progressed indicates that fecundity slowed and is evidence of only one generation per year. Peak populations of Pratylenchus scribneri and Xiphinema americanum occurred in late August or early September. Adults of Hoplolaimus galeatus were few in the roots but common in the soil, indicating that fertilization occurred mostly in the soil. Numbers of P. scribneri were generally greater at the lower depth, especially late in the season. Community diversity (H') was less when nematode biomass was used instead of numbers. Numbers of H. galeatus did not decline over the winter. Numbers of L. breviannulatus, P. scribneri, and X. americanum declined significantly over the winter, but not between spring cultivation and planting.

Effects of Several Phytoparasitic Nematodes on the Growth of Basil, Ocimum basilicum.

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.

Solarization for nematode disinfestation of small volumes of soil.

Several polyethylene plastics were evaluated as potential materials for disinfesting small volumes of soil containing nematodes. Bursaphelenchus seani, cultured on the fungus Monilinia fructicola in petri dishes, was used to bioassay the survival and reproductive capability of nematodes buried 7.5 cm deep in Margate fine sand (soil moisture = 4.9%). The soil was exposed to sunlight for 6 days in May 1987. The highest mean temperatures recorded at 7.5 cm deep were 38 +/- 1 C, 43 +/- 1 C, 43 +/- 1 C, and 50 +/- 1 C for the no plastic, clear plastic, black plastic, and clear + black plastic treatments, respectively. The temperature in the clear + black plastic treatment exceeded 47 C for more than 2 hours on clear days. Nematode survival averaged 98 +/- 3%, 78 +/- 22%, 38 +/- 38%, and 0 +/- 0%, whereas the reproductive success of B. seani following treatment was 100, 100, 75, and 0% for the no plastic, clear plastic, black plastic, and clear + black plastic treatments, respectively. Bursaphelenchus seani in petri dishes and Belonolaimus longicaudatus and Hoplolaimus galeatus in soil died when exposed to 48 +/- 2 C for 2 hours.

Evaluation of Three Nematicides for the Control of Phytoparasitic Nematodes in 'Tifgreen II' Bermudagrass.

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.

Corn response to subsoiling and nematicide application.

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.