A field study was conducted to evaluate soybean cultivar sensitivity to Pratylenchus brachyurus and selected nonfumigant nematicides for control of this nematode. 'Essex', a tolerant cultivar, yielded more than 'Forrest' , a sensitive cultivar, in an infested field. Plots treated with aldicarb, carbofuran, and fenamiphos had fewer nematodes 40 days after planting than nontreated plots. Plots planted with Forrest and treated with carbofuran had a greater yield than the untreated controls.
aldicarb; carbofuran; chemical control; fenamiphos; Glycine max; lesion nematode; Pratylenchus brachyurus
Soil temperature at planting and initial population densities (Pi) significantly affected (P < 0.05) the chemical control of Heterodera schachtii on sugarbeet, Beta vulgaris. The fumigant 1,3-dichloropropene (1,3-D) at 9.4 g/m of row effectively controlled H. schachtii, resulting in increased sugarbeet yields over the nontreated control treatment at soil temperatures at planting of 8, 12, and 16 C and Pi of 4.7, 10.4, and 18.3 eggs/cm³ at planting. A split application of aldicarb, 1.3 g/m of row at planting (AP) and 28 days later (PP), and a single at-planting (AP) treatment of 2.1 g/m of row were less effective in controlling H. schachtii than 1,3-D at the three soil temperatures and Pi. The sugarbeet yield from the AP plus PP treatment, however, was greater than the sugarbeet yield from the AP treatment and was equivalent to the yield from the 1,3-D treatment at temperatures of 8 and 12 C and a Pi of 4.7 eggs/cm³. Sugarbeet yield from the AP treatment was significantly (P < 0.05) greater than the AP plus PP application at a Pi of 18.3 at a planting temperature of 8 C and Pi of 10.4 and 18.3 eggs/cm³ at soil planting temperatures of 12 and 16 C. Postplant application of 2.1 g/m of aldicarb, applied 28 days after planting, significantly increased sugarbeet yields at all soil temperatures at the lower Pi levels.
aldicarb; Beta vulgaris; cyst nematode; Heterodera schachtii; population density; soil temperature; sugarbeet; yield
The host suitability of 64 commercial corn hybrids for a Meloidogyne arenaria race 2 population and a M. incognita race 4 population was determined in greenhouse experiments. 'Northrup King 508' and 'Pioneer Brand 3147' maintained M. arenaria below and at the initial population level, respectively, indicating that these hybrids are relatively poor hosts for this species. RF values (final egg number/initial egg number) of the hybrids for M. arenaria ranged from 0.8 for Northrup King 508 to 42.3 for 'Pioneer Brand XC941'. All hybrids were excellent hosts for M. incognita with RF values ranging from 20.7 for 'Sunbelt 1860' to 49.5 for Pioneer Brand XC941.
corn; host suitability; Meloidogyne arenaria; peanut root-knot nematode; M. incognita; southern root-knot nematode; Zea mays
A modified version of a standard greenhouse bioassay for determining soybean cyst resistance in soybean plants is described. White plastic laundry tubs served as microplots for rearing large numbers of nematodes in a confined space; up to 3 million eggs of each generation were collected per tub. Before screening, SCN populations were evaluated on susceptible and resistant soybean to characterize female development; these were periodically retested. Screening tests took place in Todd planter flats (120 plants per flat). Test plants were inoculated with 1,200 eggs per plant and evaluated for resistance 33-37 days after inoculation. The plants were pruned at the cotyledonary node which resulted in a greatly reduced root system. Staining the roots in Toluidine Blue created contrast with the white females and facilitated counting. Greenhouse space was conserved, and the labor to set up and maintain the screening test was reduced.
bioassay; cyst nematode; Glycine max; Heterodera glycines; screening; soybean
Recent published estimates of crop losses due to plant-parasitic nematodes are summarized by crop and state. Estimates are systematically reported from major producing states for cotton, peanut, tobacco, and soybean. Only scattered reports were available for nematode losses to other field crops or to vegetables and ornamentals. Among the states, North Carolina and Michigan were most consistent in reporting loss estimates from the widest range of crops.
crop loss assessment; corn; cotton; field crop; ornamental; peanut; soybean; tobacco; vegetables
One susceptible and six nematode-resistant soybean cultivars were evaluated in the field for their effects on seed yield, nematode populations, and response to the fumigant nematicide, ethylene dibromide. The soil was a loamy sand infested with Meloidogyne arenaria and Heterodera glycines. Cultivars significantly affected yield and numbers of H. glycines but did not affect M. arenaria numbers. Fumigation increased yield and reduced M. arenaria numbers but did not affect numbers of H. glycines. The interaction between cultivars and fumigation was significant for yield but not for nematode numbers.
Glycine max; Heterodera glycines; host-plant resistance; Meloidogyne arenaria; root-knot nematode; soybean; soybean cyst nematode
A field study was conducted to evaluate one susceptible and six nematode-resistant soybean cultivars for their effects on seed yield, nematode populations, and response to a fumigant nematicide, ethylene dibromide. The soil was a sandy loam, and the field was infested with a mixture of Meloidogyne incognita, M. arenaria, and Heterodera glycines. Soybean cultivars significantly affected yield and juvenile numbers of Meloidogyne spp. but did not affect the H. glycinesjuvenile population. Fumigation increased yield and numbers of H. glycines juveniles, whereas the numbers of Meloidogyne spp. juveniles were decreased. The interaction between cultivars and fumigation treatment was significant for yield but not for nematode numbers.
Glycine max; Heterodera glycines; host-plant resistance; Meloidogyne arenaria; Meloidogyne incognita; root-knot nematode; soybean; soybean cyst nematode
Twenty-four cowpea breeding lines and four cultivars were tested for resistance to Meloidogyne incognita in the greenhouse. Gall and egg mass ratings indicated a range of responses from susceptible to highly resistant. Five breeding lines - VS84-2, VS84-8, VS84-12, VS84-14, and VS84-22 - and the cultivar Erectset had gall and egg mass ratings comparable to the M. incognita-resistant cultivar Mississippi Silver. All of these were also resistant to M. arenaria. Significantly fewer M. incognita juveniles were found in roots of resistant than in roots of susceptible plants at 7 and 21 days after inoculation; however, no differences were found at 14 days.
breeding line; cowpea; Meloidogyne incognita; Meloidogyne arenaria; resistance; root-knot nematode; southern pea; Vigna unguiculata
The effects of aldicarb on soybean cyst (Heterodera glycines) and root-knot (Meloidogyne incognita and M. arenaria) nematode populations, early season insect pests and soybean (Glycine max) yield were evaluated in five field experiments in northern and southern Alabama. Aldicarb significantly (P = 0.05) reduced nematode populations in only two cases: M. arenaria in Centennial soybean in the Wiregrass site and M. incognita in Bedford soybean in a Tennessee Valley site. No significant difference (P = 0.05) in mean percentage main stem or petiole girdling by threecornered alfalfa hopper (Spissistilus festinus) or in mean number of plants damaged by lesser cornstalk borer (Elasmopalpus lignosellus) occurred among treatments in any experiment. Soybean yields were significantly (P = 0.05) increased in only two cases: in the nematode susceptible Essex and Cobb cultivars planted in the Tennessee Valley and Gulf Coast sites, respectively. Unusually dry 1986 weather conditions may have reduced the activity of aldicarb.
Meloidogyne arenaria; Meloidogyne incognita; Heterodera glycines; Spissistilus festinus; Elasmopalpus lignosellus; aldicarb; soybean; Glycine max
Analysis of soil and root samples collected from potato fields across Prince Edward Island and the Woodstock-Grand Falls region of New Brunswick, Canada showed that Pratylenchus spp. were the dominant plant-parasitic nematodes. Pratylenchus penetrans occurred more often on Prince Edward Island, and P. crenatus predominated in New Brunswick. It was estimated that about 10% of the sites from Prince Edward Island had population levels of Pratylenchus spp. that may have caused economic losses.
potato; Pratylenchus penetrans; P. crenatus; root lesion nematode; Solanum tuberosum
A survey was conducted over a 22-year period to evaluate the influence of soil texture and land use on the geographical distributions of Rotylenchulus reniformis, Meloidogyne incognita, and Tylenchulus semipenetrans in the lower Rio Grande valley. The distributions of R. reniformis and M. incognita were related to soil texture, whereas T. semipenetrans occurred wherever host plants were present regardless of soil texture. The incidence of M. incognita was greatest in elevated sandy loams and moderately well-drained silts of modern flood terraces of the Rio Grande river. Rotylenchulus reniformis occurred predominantly in clay silts and clays of ancient flood terraces. Clay loams and sandy clay loams of the central, irrigated portion of the lower Rio Grande valley appeared favorable for M. incognita and R. reniformis. Differences between the geographical distributions of these two species could not be attributed to host crops.
citrus; geographical distribution; Meloidogyne incognita; population ecology; Rotylenchulus reniformis; survey; TylenchuIus semipenetrans
Meloidogyne hapla is the dominant root-knot nematode found in Tennessee woody ornamental nurseries. In greenhouse tests, M. hapla produced galls and formed egg masses on roots of Abelia x grandiflora, Comus florida, Hydrangea paniculata grandiflora, Photinia x fraseri, Spiraea x bumalda, Spiraea x vanhouttei, and Viburnum carlesii. Galls on H. grandiflora and V. carlesii were mostly large and fusiform. Galls on C. florida were spherical and usually terminal, whereas those on the other species were minute. Lateral roots grew from galls on all susceptible plants. Two Acer spp., two Buxus spp., three llex spp., five Prunus spp., three Rhododendron spp., Euonymus alata, Ligustrum sinense, Magnolia x soulangiana, Nandina domestica, and nine conifer species were nonhosts or very poor hosts.
Meloidogyne hapla; northern root-knot nematode; nursery; quarantine; host-parasite relationship
The efficacy of methyl bromide for control ofMeloidogyne arenaria and to increase yields of 'Florunner' peanut (Arachis hypogaea) was studied in a field at the Wiregrass Substation near Headland, Alabama. Methyl bromide was applied in the row at a depth of 35 cm using a subsoiler-bedder 2 weeks before planting at rates of 0, 34, 50, 67, 101, and 118 kg a.i./ha. Methyl bromide treatments of 67 kg a.i./ha or higher resulted in significant (P = 0.05) yield increases similar to those obtained in the same experiment with at-plant applications of aldicarb (2.2 kg a.i./ha), EDB (1.55 ml a.i./m row), or 1,3-D (5.10 ml a.i./m row). The relation between yield (Y) and methyl bromide rate (x) was described (R² = 0.97**) by the exponential function: Y = 2,302.963eb, where b = (- 1.901 - ln x)²/169.482. M. arenaria juvenile populations in soil in mid-August were too low to permit establishment of a relation between application rate of methyl bromide and size of the population.
aldicarb; Arachis hypogaea; chemical control; ethylene dibromide; methyl bromide; peanut; pest management
Significant (P < 0.05) differences among galling and yields of 41 soybean cultivars and breeding lines were found when they were produced at a site infested with Meloidogyne incognita during 3 years of investigation. Over a period of 6 years of testing, 13 cultivars were identified as having a suitably low susceptibility to warrant their production in M. incognita infested soil.
Glycine max; Meloidogyne incognita; plant breeding; root-knot nematode; soybean
Efficacy of three rates of aldicarb for control of Hoplolaimus columbus was evaluated on highly tolerant ('Foster'), moderately tolerant ('Coker 368'), and highly susceptible ('Braxton') soybean cultivars planted on 28 June 1985. Average yields of the nontreated cultivars were 557 kg/ha for Braxton, 1,309 kg/ha for Coker 368, and 1,682 kg/ha for Foster. Yield differences were significant. Aldicarb increased yields of all three cultivars, with the most tolerant cultivar responding to all aldicarb rates and the most susceptible cultivar responding only to the low rate of aldicarb; there was no significant response to the higher rates. H. columbus population densities in the soil 6 weeks after planting were not affected by either aldicarb treatment or cultivar, whereas the populations from roots were reduced in all cultivars by aldicarb. No relationship between tolerant soybean cultivars and population densities of H. columbus was observed.
aldicarb; Columbia lance nematode; Glycine max; Hoplolaimus columbus; soybean; tolerance
Population development of lesion nematodes was measured in 17 inbred lines of South Dakota and A619Ht dent corn. In two greenhouse groundbed tests, lines SD 101, SD 102, and SD 103 supported fewer than 1,000 Pratylenchus hexincisus per gram of dry root after 12 weeks. In an irrigated field test, inbred SD101 supported fewer than 1,000 P. scribneri per gram of dry root on each of two sampling dates, whereas line A619Ht supplied high populations of P. scribnerni on both dates. Inbreds SD45, 84742, and 84763 supported high populations of both P. hexincisus and P. scribneri.
corn; corn breeding; lesion nematode; maize; Pratylenchus; reproduction; resistance; Zea mays
The efficacies of Heterodera glycines-resistant 'Fayene' soybean and aldicarb for managing H. glycines were compared to the experimental nematicides DS-47187 10F, DS-47357 10F, DS-48145 10F, DS-48165 10F, DS-46995 10F and 5G, and DS-38697 5G during 1981-83. Yield of Fayette was greater than yield of the H. glycines-susceptible cultivar treated with nematicide in 1981 and 1983. Yield of aldicarb-treated soybean was greater than yield of soybean treated with experimental nematicides in 1983. There were no yield differences in 1982. Fewer white females were recovered from Fayette 5 weeks after planting than from soybean treated with nematicides in 1981 and 1982, but not in 1983. Fewer white females were recovered from aldicarb-treated soybean than from experimental nematicide-treated soybean in 1983 but not in 1981 and 1982. In 1983 numbers of first generation white females at 5 weeks and the ratio of those white females to gravid cysts at planting were negatively correlated with soybean yield when soybean was severely damaged by the nematode, but the ratio of final eggs and second-stage juveniles to initial eggs and second-stage juveniles was not correlated with yield.
aldicarb; chemical control; Glycine max; Heterodera glycines; management; population dynamics; resistance; soybean; soybean cyst nematode
application rate; calibration; dosage; nematicide; rate; standardization
A Tylenchulus sp. found in a Georgia peach orchard parasitized peach roots in the greenhouse. Citrus roots were not parasitized, indicating that the nematode was not the citrus nematode. Morphologically similar populations were found in one peach orchard in Alabama, two orchards in Arkansas, and one in South Carolina. Males were present in the Alabama populations and one of the Arkansas populations. A population was also found in an area of mixed hardwood and pine in Arkansas. The populations are morphologically different from the citrus nematode Tylenchulus semipenetrans.
Alabama; Arkansas; citrus nematode; Georgia; peach; South Carolina; Tylenchulus
Two experiments, one site per year, were conducted in Scotland County, North Carolina, to determine the usefulness of selected cultivars and nematicides for limiting soybean losses due to Hoplolaimus columbus. Coker 317 was relatively tolerant to this nematode, and Coker 156, Centennial, Dehapine 105, and Gordon were generally intolerant. Most nematicides significantly increased soybean yields, and many gave an economic return.
columbia lance nematode; Glycine max; Hoplolaimus columbus; nematicide; soybean; tolerance
The effects of nematicides carbofuran (C) and fenamiphos (F) and herbicides metribuzin (M) and trifluralin (T), alone and in combination, on hatching, penetration, development, and reproduction of Meloidogyne incognita race 3 were determined under laboratory conditions. To study hatching, entire egg masses were exposed to nematicides (6 μg/ml), herbicides (0.5 μg/ml), and their combinations over a period of 16 days; the hatched juveniles were extracted and counted every 48 hours. Second-stage juveniles that hatched from day 6 to day 8 were used as inoculum to determine the effects of the chemicals on penetration, development, and reproduction of M. incognita on tomato 4, 16, and 32 days after inoculation. F, F + T, and F + M inhibited hatching; whereas, C, T, M, C + T, and C + M did not affect hatching, penetration, development of females, or reproduction. Since so few juveniles hatched from the fenamiphos treatments, we were not able to use them for the postinfection development study. There was no apparent reduction in the effect of the nematicides by the herbicides.
carbofuran; fenamiphos; hatching; herbicide; life cycle; Meloidogyne incognita; metribuzin; nematicide; pesticide interaction; root-knot nematode; survival; trifluralin
Field experiments compared pesticidal and plant growth effects of soil solarization, alone and in combination, with overall applications of several nematicides. Nematodes, including Meloidogyne incognita J2, that were targeted for control were significantly reduced (P < 0.05) by solarization, 1,3-dichloropropene (44 and 132 liter/ha), ethoprop (13.5 kg/ha), metham sodium (64 liter/ha), formaldehyde (111 liter/ha), and by solarization-nematicide combinations. Control of Pythium ultimum also was obtained by all of the treatments; however, none of the chemicals or combinations of chemicals and solarization controlled nematodes or P. ultimum significantly better than solarization alone. Numbers of cotton (Gossypium hirsutum cv. Acala SJ-2) seed-applied Trichoderma viride and Bacillus subtilis which colonized the plant rhizosphere were not affected. Yield of carrot and survival of cotton seedlings was sometimes increased by solarization and (or) chemical treatments. No significant phytotoxicity from soil treatments was found on cotton or carrot.
Bacillus subtilis; biological control; chemical control; Criconemella xenoplax; Daucus carota; 1,3-dichloropropene; ethoprop; formaldehyde; Gossypium hirsutum; Meloidogyne incognita; metham sodium; Pythium ultimum; ring nematode; solarization; southern root-knot nematode; Trichoderma viride
Little information is available regarding the levels of Meloidogyne incognita race 3 resistance in Acala 1517 cotton cultivars compared with cultivars grown outside the southwestern United States. Levels of M. incognita egg production were compared among commercial Acala cultivars 1517-E2, 1517-SR1, 1517-75, 1517-77BR, and SJ-5, resistant and susceptible standards Auburn 634 and M-8 and breeding lines Acala 5701-W and N6072 grown for 45 days in the greenhouse. The Acala 1517 cultivars all performed similarly, demonstrating moderate nematode resistance. Egg production on the 1517 cultivars was less than on SJ-5 and less than one-fifth that on M-8. Auburn 634 was most resistant, followed by N6072. Total egg production per plant and egg production per gram dry root were not correlated but proved to be reliable indicators of relative resistance to M. incognita.
Gossypium hirsutum; cotton; Meloidogyne incognita; root-knot nematode; resistance
Results of surveys from 1978 to 1986 to estimate and identify nematodes in Arkansas soybean fields are presented. The seven most common nematode species in the fields were Heterodera glycines, Quinisulcius acutus, Pratylenchus scribneri, P. alleni, Helicotylenchus pseudorobustus, Tylenchorhynchus ewingi, and Xiphinema americanum. Other nematodes identified from these fields were Pratylenchus brachyurus, P. vulnus, P. zeae, Tylenchorhynchus canalis, T. goffarti, T. martini, Helicotylenchus dihystera, Scutellonema bradys, Xiphinema chambersi, X. rivesi, Hoplolaimus galeatus, H. magnistylus, Paratrichodorus minor (P. christiei), Paratylenchus projectus, P. tenuicaudatus, Criconemella macrodora, C. ornata, and Meiodorus hollisi.
Arkansas; crop lossestimate; Helicotylenchus pseudorobustus; Heterodera glycines; infestation estimate; Pratylenchus alleni; P. scribneri; Quinisulcius acutus; soybean; Tylenchorhynchus ewingi; Xiphinema americanum