scholarly journals Incidence, Population Density, and Spatial Heterogeneity of Plant-Parasitic Nematodes in Corn Fields in Ohio

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2453-2464 ◽  
Author(s):  
Abasola C. M. Simon ◽  
Horacio D. Lopez-Nicora ◽  
Laura E. Lindsey ◽  
Terry L. Niblack ◽  
Pierce A. Paul
Keyword(s):  
Population Density ◽  
Spatial Scales ◽  
Management Strategies ◽  
Parasitic Nematodes ◽  
Growth Stages ◽  
Plant Parasitic Nematodes ◽  
Population Densities ◽  
Sampling Protocols ◽  
Corn Fields ◽  
Plant Parasitic

Soil samples were collected from 425 corn fields in 28 Ohio counties between growth stages V3 and V6 during the 2013 and 2014 growing seasons. Ten morphological groups of plant-parasitic nematodes, namely spiral, lesion, lance, dagger, stunt, pin, ring, stubby-root, cyst, and “tylenchids” (several genera morphologically similar to members of the subfamily Tylenchinae [NCBI Taxonomy] including Cephelenchus, Filenchus, Malenchus, and Tylenchus) were identified. Eight species belonging to six of these groups were characterized. Spiral, tylenchids, lesion, pin, lance, stunt, and dagger nematodes were detected in 94, 96, 80, 57, 48, 48, and 37% of the fields, respectively, whereas the stubby-root, cyst, and ring nematodes were present in fewer than 14% of the samples. Averaged across fields, the spiral, tylenchids, and pin nematodes had the highest mean population densities. For all groups, incidence and population density varied among counties, and in some cases, among soil regions and cropping practices. Both population parameters were heterogeneous at multiple spatial scales, with the lowest heterogeneity among soil regions and the highest among fields within county and soil region. Estimated variances at the soil region level were not significantly different from zero for most of the nematodes evaluated. Stunt and lance were two of the most variable groups at all tested spatial scales. In general, the population densities were significantly more heterogeneous at the field level than at the county level. Findings from this study will be useful for developing sampling protocols and establishing on-farm trials to estimate losses and evaluate nematode management strategies.

scholarly journals Cropping Practices and Soil Properties Associated with Plant-Parasitic Nematodes in Corn Fields in Ohio

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2519-2530 ◽  
Author(s):  
A. C. M. Simon ◽  
Horacio D. Lopez-Nicora ◽  
Terry L. Niblack ◽  
Elizabeth A. Dayton ◽  
David Tomashefski ◽  
...  
Keyword(s):  
High Risk ◽  
Population Density ◽  
Soil Ph ◽  
Nematode Population ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Population Densities ◽  
Risk Levels ◽  
Corn Fields ◽  
Plant Parasitic

Ten morphological groups of plant-parasitic nematodes (spiral, lesion, lance, dagger, stunt, pin, ring, stubby-root, cyst, and miscellaneous tylenchids) were detected in corn fields in Ohio, but the presence and population density of these groups varied among fields. Binary and ordinal logistic regression models were fitted to the data to estimate the odds of each group being present, and the lesion, lance, spiral, and pin nematode population densities being at moderate-high risk levels based on soil region, cropping sequence, tillage, and soil pH, silt content, and electrical conductivity. All covariates were associated with at least one nematode group, but soil region had the greatest and most consistent effect. Dagger and ring nematodes were more likely to be present in region 6 than in any of the other regions, whereas lance, stunt, pin, stubby-root, and spiral nematodes were more likely to be present in regions 1 to 5 than 6. Spiral, lance, and pin nematode population densities were more likely to be at moderate-high risk levels in regions 3 and 4 than in region 6. Fields under conservation tillage were two times more likely to have moderate-high risk lance nematode population densities than fields under conventional tillage. Similarly, pin nematode population densities were two times more likely to be at moderate-high risk levels in fields under rotation than in continuous corn. For every unit increase in soil pH, the odds of the spiral nematode population density being at moderate-high risk levels increased by 43%, but the odds of the lesion and pin nematode population densities being at the same risk level decreased by 63 and 29%, respectively. The predicted probability of lesion and lance population densities being at moderate-high risk levels decreased as the silt content of the soil increased. These finding will be useful for developing future nematode sampling protocols and for assessing the risk associated with nematodes in corn fields in Ohio.

The role of plant-parasitic nematodes in reducing yield of sugarcane in fine-textured soils in Queensland, Australia

2007 ◽  
Vol 47 (5) ◽  
pp. 620 ◽  
Author(s):  
B. L. Blair ◽  
G. R. Stirling
Keyword(s):  
Growth And Yield ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Population Densities ◽  
Lesion Nematode ◽  
Yield Responses ◽  
The Impact ◽  
Stalk Length ◽  
Plant Parasitic

Damage to sugarcane caused by root-knot nematode (Meloidogyne spp.) is well documented in infertile coarse-textured soils, but crop losses have never been assessed in the fine-textured soils on which more than 95% of Australia’s sugarcane is grown. The impact of nematodes in these more fertile soils was assessed by repeatedly applying nematicides (aldicarb and fenamiphos) to plant and ratoon crops in 16 fields, and measuring their effects on nematode populations, sugarcane growth and yield. In untreated plant crops, mid-season population densities of lesion nematode (Pratylenchus zeae), root-knot nematode (M. javanica), stunt nematode (Tylenchorhynchus annulatus), spiral nematode (Helicotylenchus dihystera) and stubby-root nematode (Paratrichodorus minor) averaged 1065, 214, 535, 217 and 103 nematodes/200 mL soil, respectively. Lower mean nematode population densities were recorded in the first ratoon, particularly for root-knot nematode. Nematicides reduced populations of lesion nematode by 66–99% in both plant and ratoon crops, but control of root-knot nematode was inconsistent, particularly in ratoons. Nematicide treatment had a greater impact on shoot and stalk length than on shoot and stalk number. The entire community of pest nematodes appeared to be contributing to lost productivity, but stalk length and final yield responses correlated most consistently with the number of lesion nematodes controlled. Fine roots in nematicide-treated plots were healthier and more numerous than in untreated plots, and this was indicative of the reduced impact of lesion nematode. Yield responses averaged 15.3% in plant crops and 11.6% in ratoons, indicating that nematodes are subtle but significant pests of sugarcane in fine-textured soils. On the basis of these results, plant-parasitic nematodes are conservatively estimated to cost the Australian sugar industry about AU$82 million/annum.

scholarly journals First Report of the Spiral Nematode Scutellonema brachyurum on Lilyturf in the United States

Plant Disease ◽  
2011 ◽  
Vol 95 (1) ◽  
pp. 74-74 ◽  
Author(s):  
P. Agudelo ◽  
D. Harshman
Keyword(s):  
United States ◽  
Population Density ◽  
The United States ◽  
Parasitic Nematodes ◽  
Initial Population ◽  
Herbaceous Plant ◽  
Plant Parasitic Nematodes ◽  
Essential Information ◽  
First Report ◽  
Plant Parasitic

Lilyturf (Liriope muscari (Decne.) L.H. Bailey), an herbaceous plant, is commonly used in landscaping including borders (along sidewalks, driveways, and trees) and mass plantings as groundcover in the southeastern United States. In December of 2009, a soil sample was submitted to our lab for diagnosis of plant-parasitic nematodes from an area planted with lilyturf located on the Clemson University main campus. A high population density (1,220 individuals/100 cm3 of soil) of spiral nematodes (Scutellonema brachyurum (Steiner, 1938) Andrássy, 1958) was found by routine extraction by sugar centrifugal flotation (3). Other plant-parasitic nematodes, mainly ring nematodes (10 individuals/100 cm3) and stubby root nematodes (10 individuals/100 cm3), were present. To verify if high numbers of spiral nematodes were consistently associated with lilyturf, 20 additional soil and root samples were collected from different places on the campus. In all cases, S. brachyurum was found in densities ranging from 680 to 1,600 individuals/100 cm3 of soil (average of 1,210 individuals/100 cm3). The species was identified by morphological characters of females, including well developed stylet (26 to 30 μm long), no spermatheca, no sperm in uterus, tail broadly rounded with 8 to 12 annules between anus and tail, and scutella at anus level. As is commonly the case for this species, no males were found in any of the samples collected. Examination of the roots revealed numerous, small, reddish brown, necrotic lesions, apparently caused by the feeding and penetration of S. brachyurum. Host plant suitability and pathogenicity of the nematode were tested in the greenhouse. Ten nematode-free lilyturf plants grown individually in 15-cm-diameter plastic pots with pasteurized soil were inoculated with 1,000 spiral nematodes each. Ten uninoculated plants were kept under identical conditions as controls. Three months after inoculation, soil population densities were measured and reproduction factors were calculated to be between 2.8 and 5.4 (final population density divided by initial population density) for the 10 plants. Characteristic lesions previously described were observed in the roots of all inoculated plants, along with slight chlorosis of foliage. These symptoms were not observed on control plants. Spiral nematodes may attack the roots and stolons of lilyturf as ectoparasites or they may enter them and feed in the cortex as endoparasites. Although root lesions were common on affected plants, root injury in general was not severe and generalized root decay was not observed on either the collected plants or those from the greenhouse study. Reports on the pathogenicity of S. brachyurum are variable. Moderate damage was recorded on amaryllis and other ornamentals (4), while measurable damage was observed on tobacco (2), with approximately 100 individuals/100 cm3 of soil, and severe damage on Aloe vera ((L.) Burm. f.), with approximately 500 individuals/100 cm3 (1). To our knowledge, this is the first report of S. brachyurum causing visible symptoms on lilyturf. As the interstate and international movement of perennial plants continues to grow, awareness of the host status of potentially harmful nematodes becomes essential information. References: (1) R. P. Esser et al. Nematropica 16:65, 1986. (2) T. W. Graham. Phytopathology (Abstr.) 45:347, 1955. (3) W. R. Jenkins. Plant Dis. Rep. 48:692, 1964. (4) L. Nong and G. F. Weber. (Abstr.) Phytopathology 54:902, 1964.

Diversity and incidence of plant-parasitic nematodes associated with saffron (Crocus sativus L.) in Morocco and their relationship with soil physicochemical properties

Nematology ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 87-102 ◽  
Author(s):  
Fouad Mokrini ◽  
Salah-Eddine Laasli ◽  
Youssef Karra ◽  
Aicha El Aissami ◽  
Abdelfattah A. Dababat
Keyword(s):  
Physicochemical Properties ◽  
Parasitic Nematode ◽  
Management Strategies ◽  
Plant Parasitic Nematode ◽  
Crocus Sativus ◽  
Parasitic Nematodes ◽  
Soil Physicochemical Properties ◽  
Plant Parasitic Nematodes ◽  
Starting Point ◽  
Plant Parasitic

Summary Saffron (Crocus sativus) fields in Morocco’s Taliouine and Taznakht regions were surveyed between January and April 2018 to study the diversity and incidence of plant-parasitic nematodes and assess the effects of soil physicochemical properties on the nematodes. Fourteen nematode genera were identified in soil and root samples collected from 66 saffron fields. The most common plant-parasitic nematodes in the Taliouine region were Pratylenchus spp. and Helicotylenchus spp. In the Taznakht region, the most common nematodes were Pratylenchus spp., Tylenchorhynchus spp. and Ditylenchus dipsaci. Nematodes, particularly Pratylenchus spp. and Ditylenchus spp., were abundant and frequent throughout the region. Several nematode genera were significantly associated with soil texture and mineral content, indicating that soil properties play an important role in plant-parasitic nematode communities. This description of plant-parasitic nematode assemblages associated with saffron fields in Morocco and their relationship with soil physicochemical properties provides a starting point from which appropriate nematode management strategies can be implemented.

scholarly journals Short-Term Effects of Sublethal Doses of Nematicides on Meloidogyne incognita

2019 ◽  
Vol 109 (9) ◽  
pp. 1605-1613 ◽  
Author(s):  
Catherine L. Wram ◽  
Inga A. Zasada
Keyword(s):  
Population Density ◽  
Meloidogyne Incognita ◽  
Cultivated Plants ◽  
Parasitic Nematodes ◽  
Initial Population ◽  
Plant Parasitic Nematodes ◽  
Water Control ◽  
Effective Doses ◽  
Sublethal Doses ◽  
Plant Parasitic

Meloidogyne species are one of the most important groups of plant-parasitic nematodes globally because of their ability to damage most cultivated plants. Although they are widespread and economically important, there are limited control measures to combat these nematodes. New nonfumigant nematicides have been discovered that have the potential to be widely utilized for the management of plant-parasitic nematodes. Because of the longer half-lives in soil and lower toxicity of new nematicides compared with traditional fumigant and nonfumigant nematicides, understanding how nematodes respond to sublethal doses of nematicides is imperative to understanding whether nematicide resistance has the potential to develop. Characterizing responses of nematodes to sublethal doses will provide the foundation for future work, such as gene expression studies. In this study, the nematicides oxamyl (Vydate), fluazaindolizine (Salibro), fluensulfone (Nimitz), and fluopyram (Velum), were evaluated to understand how sublethal doses affect the fecundity and mobility of Meloidogyne incognita second-stage juveniles (J2). Using a microwell assay system, dose-response curves for each nematicide were established for M. incognita J2. Fluopyram was the most toxic nematicide, with effective doses up to 230 times lower than that of other nematicides. The other nematicides had predicted ED50 values (effective doses that resulted in 50% of the population becoming inactive) of 89.4, 131.7, and 180.6 ppm for oxamyl, fluensulfone, and fluazaindolizine, respectively. The 24-h ED50 of each nematicide was then used in both motility and infectivity assays. The motility and activity of M. incognita J2 exposed to ED50 doses of fluazaindolizine and fluensulfone was significantly reduced, with nematodes initially being motile but eventually becoming inactive. However, the motility of M. incognita J2 exposed to ED50 doses of fluopyram and oxamyl was not different from a water control. In a pot assay, M. incognita J2 exposed to ED50 doses of fluazaindolizine, oxamyl, and fluensulfone were unable to reproduce on tomato, with reproduction factors (RF = final population density/initial population density) of 0 to 0.03. Fluopyram did not reduce reproduction of M. incognita, with a mean RF of 38.7 ± 4.5, which was similar to the RF of 46.3 ± 4.6 for the water control. This study is the first comprehensive evaluation of M. incognita activity, motility, and fecundity after exposure to the traditional nematicide, oxamyl, as well as three new nematicides, fluazaindolizine, fluopyram, and fluensulfone.

Population dynamics of plant parasitic nematodes in Queensland pineapple fields and the effects of these nematodes on pineapple production

1993 ◽  
Vol 33 (2) ◽  
pp. 197 ◽  
Author(s):  
GR Stirling ◽  
A Nikulin
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Ratoon Crop ◽  
Original Population ◽  
Ethylene Dibromide ◽  
Nematode Population Density ◽  
Plant Parasitic

Twelve pineapple fields with various densities of root-knot nematode were selected during a ratoon crop. Nematode populations were monitored regularly after the crop was ploughed out. Regardless of the original population density, rootknot nematodes were almost nondetectable at the end of the subsequent 3-6-month fallow intercycle period. In the absence of nematicide treatment there were marked differences between sites in the manner in which rootknot nematodes increased in the newly planted crop. At some sites, they were detectable 9-15 months after planting, whereas at other sites, nematodes were not observed at 15 months. Increases in ratoon crop yield following application of ethylene dibromide or fenamiphos were related to root-knot nematode population density. Significant increases in yield were not obtained at sites where the nematode was not detectable at 15 months. The results suggest that some pineapple growers are needlessly applying nematicides and that nematode diagnostic services should be developed to provide growers with advice on their nematode management programs.

The impact of management strategies on the development and status of potato cyst nematode populations in Switzerland: An overview from 1958 to present

Plant Disease ◽  
2021 ◽  
Author(s):  
Andrea Caroline Ruthes ◽  
Paul Dahlin
Keyword(s):  
Integrated Management ◽  
Abiotic Factors ◽  
Management Strategies ◽  
Monitoring Program ◽  
Cyst Nematode ◽  
Globodera Pallida ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
The Impact ◽  
Plant Parasitic

Globodera rostochiensis and Globodera pallida are some of the most successful and highly specialized plant-parasitic nematodes, and appear among the most regulated quarantine pests globally. In Switzerland, they have been monitored by annual surveys since their first detection in Swiss soil, in 1958. The dataset created was reviewed to give an overview of the development and actual status of PCN in Switzerland. Positive fields represent 0.2% of all the samples analyzed, and currently their distribution is limited to central-west and western Switzerland, suggesting that new introduction of PCN and the spread of the initial introduced PCN populations did not occur. In this way, the integrated management used in Switzerland appears to be effective. However, the increasing availability of potato varieties with resistance to G. rostochiensis and the limited availability of varieties with resistance to G. pallida, together with other biotic and abiotic factors promoted changes in the dominance of either species. Consequently, an extended monitoring program would be of interest to Swiss farmers, to avoid favoring virulent traits that could be present within Swiss Globodera populations.

scholarly journals Survey of Plant-Parasitic Nematodes in Kansas and Eastern Colorado Wheat Fields

2014 ◽  
Vol 15 (3) ◽  
pp. 112-117 ◽  
Author(s):  
T. C. Todd ◽  
J. A. Appel ◽  
J. Vogel ◽  
N. A. Tisserat
Keyword(s):  
Great Plains ◽  
Yield Loss ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Population Densities ◽  
Economic Thresholds ◽  
Lesion Nematodes ◽  
Maximum Root ◽  
Root Lesion Nematodes ◽  
Plant Parasitic

Observations on the prevalence and abundance of plant-parasitic nematodes were made from soil and root samples collected from 2,640 wheat fields in Kansas and Colorado during 2007-2010. Stunt nematodes (predominately Merlinius brevidens and Quinisulcius acutus), root-lesion nematodes (predominately Pratylenchus neglectus), and pin nematodes (Paratylenchus projectus) were the most commonly encountered taxa. Maximum soil population densities of 6,520 and 1,880 nematodes/100 cm3 soil were observed for pin and stunt nematodes, respectively, while a maximum root population density of 90,309 nematodes/g dry root was observed for root-lesion nematodes. Lower nematode densities were associated with wheat following corn, grain sorghum, or soybean for pin and stunt nematodes, and with wheat following fallow for root-lesion nematodes. Based on the results of this survey, 6% and 8% of wheat acreage in the central Great Plains are estimated to be at risk for significant (>5%) yield loss due to stunt nematodes and root-lesion nematodes, respectively. The number of fields with high population densities of both stunt and root-lesion nematodes was negligible (1%); therefore, the total wheat acreage with nematode populations above provisional economic thresholds is estimated to be ∼13%. Damage relationships with greater accuracy, precision, and relevance are necessary to establish reliable yield loss estimates for this region. 3 June 2014. 11 August 2014.

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