The importance of plant-parasitic nematodes as yield-limiting pathogens of cotton has received increased recognition and attention in the United States in the recent past. This paper summarizes the remarks made during a symposium of the same title that was held in July 2007 at the joint meeting of the Society of Nematologists and the American Phytopathological Society in San Diego, California. Although several cultural practices, including crop rotation, can be effective in suppressing the populations of the important nematode pathogens of cotton, the economic realities of cotton production limit their use. The use of nematicides is also limited by issues of efficacy and economics. There is a need for development of chemistries that will address these limitations. Also needed are systems that would enable precise nematicide application in terms of rate and placement only in areas where nematode population densities warrant application. Substantial progress is being made in the identification, characterization and mapping of loci for resistance to Meloidogyne incognita and Rotylenchulus reniformis. These data will lead to efficient marker-assisted selection systems that will likely result in development and release of nematode-resistant cotton cultivars with superior yield potential and high fiber quality.
The effects of the application of poultry litter at 0.0, 6.7, 13.4, and 20.1 tons/ha on population changes during the growing season on nematode communities were evaluated in two cotton production fields in North Carolina. Numbers of bactivorous nematodes increased at midseason in response to the rate at which litter was applied but decreased with increasing litter application rates at cotton harvest. Numbers of fungivores at cotton harvest were related positively to the rate of litter applied, and this affected a positive increase in the fungivore-to-bacterivore ratio at this sampling date. The rate at which poultry litter was applied resulted in an increase in the bacterivore to plant-parasite ratio, and this corresponded with increased cotton lint yield. Trophic diversity was increased by litter application rate at cotton harvest at one location but not at another. The plant-parasite maturity index was greater consistently at one site than at a second site where the Hoplolaimus columbus population density was above the damage threshold for cotton. The population density of H. columbus was suppressed with increasing rates of poultry litter application, but other plant-parasitic nematodes were affected marginally.
Columbia lance nematode; community structure; cotton; ecology; Gossypium hirsutum; Helicotylenchus dihystera; Hoplolaimus columbus; management; nematode; Paratrichodorus minor; poultry litter; population changes; Pratylenchus brachyurus; soil health; trophic groups
The effectiveness of selected cultural practices in managing the Columbia lance nematode, Hoplolaimus columbus, on cotton was evaluated in experiments in growers' infested fields. The effects of planting date, cotton cultivar, treatment with the growth regulator mepiquat chloride, and destruction of cotton-root systems after harvest on cotton-lint yield and population densities of H. columbus were studied. The yield of cotton cultivar Deltapine 50 was negatively related (P = 0.054) to initial population density of H. columbus whereas the yield of Deltapine 90 was not affected by preplant density of this nematode, indicating tolerance in Deltapine 90. Reproduction of this nematode did not differ on the two cultivars. Planting date and treatment with the growth regulator mepiquat chloride did not influence cotton yield in a consistent manner. Application of mepiquat chloride suppressed (P ≤ 0.05) numbers of Columbia lance nematode, although there was an interaction (P ≤ 0.05) with cultivar and year. Early vs. late destruction of cotton-root systems did not impact population densities of this nematode either year, and had no impact on the subsequent cotton crop. The nematicide fenamiphos increased (P ≤ 0.03) cotton yield when H. columbus numbers exceeded the damage threshold.
columbia lance nematode; cotton; crop loss; cropping system; cultural practices; Gossypium hirsutum; Hoplolaimus columbus; host-plant tolerance; management; nematode; planting date
One-year crop rotations with corn or highly resistant soybean were evaluated at four locations for their effect on Rotylenchulus reniformis population levels and yield of a subsequent cotton crop. Four nematicide (aldicarb) regimes were included at two of the locations, and rotation with reniform-susceptible soybean was included at the other two locations. One-year rotations to corn or resistant soybean resulted in lower R. reniformis population levels (P ≤ 0.05) than those found in cotton at three test sites. However, the effect of rotation on nematode populations was undetectable by mid-season when cotton was grown the following year. Cotton yield following a one-year rotation to resistant soybean increased at all test locations compared to continuous cotton, and yield following corn increased at three locations. The optimum application rate for aldicarb in this study was 0.84 kg a.i./ha in furrow. Side-dress applications of aldicarb resulted in yield increases that were insufficient to cover the cost of application in 3 of the 4 years.
aldicarb; corn; cotton; crop loss; crop rotation; Glycine max; Gossypium hirsutum; reniform nematode; Rotylenchulus reniformis; soybean; Zea mays
Transgenic soybean cultivars, resistant to glyphosate herbicide in maturity groups V and VI, were evaluated for tolerance to the Columbia lance nematode, Hoplolaimus columbus, in field experiments conducted in 1998 and 1999. Treatment with 43 liter/ha of 1,3-dichloropropene was effective in suppressing H. columbus population densities in a split-plot design. Fumigation increased soybean yield, but a significant cultivar × fumigation interaction indicated variation in cultivar response to H. columbus. A tolerance index (yield of nontreated ÷ yield of treated × 100) was used to compare cultivar differences. Two cultivars in maturity group VI and one cultivar in maturity group V had a tolerance index greater than 90, indicating a high level of tolerance.
Columbia lance nematode; crop loss; fumigant nematicide; Glycine max; glyphosate; herbicide-resistant crops; Hoplolaimus columbus; host-plant tolerance; nematode; soybean
Selected cotton cultivars were evaluated for resistance to the southern root-knot nematode, Meloidogyne incognita, in greenhouse and field experiments. Cotton cultivars LA 887, Auburn 634, and NemX cotton were highly resistant to three North Carolina populations of root-knot nematode in greenhouse experiments compared to susceptible cultivars. The relative susceptibility of cultivars tested in the greenhouse from most to least susceptible were Deltapine 16 > Deltapine 50 > LA 887 or NemX > Auburn 634. The yields of resistant and susceptible cotton cultivars were increased by fumigation in fields infested with root-knot nematode. Reproduction of M. incognita in field plots on NemX, Paymaster H 1560, and Stoneville LA 887 was less than on susceptible cultivars. Diminished reproduction of the nematode on resistant cultivars may reduce the need for nematode control tactics in subsequent years.
crop loss; host-plant resistance; nematode; southern root-knot nematode
Yield of the soybean (Glycine max) cultivar Hartwig with resistance to all races of Heterodera glycines was compared to that of the susceptible cultivar, Deltapine 105, in a field infested with race 2 of this pathogen. The field had previously been in a cropping sequence experiment that provided a range of H. glycines population densities affording the opportunity to evaluate yield potential of resistant and susceptible cultivars in the presence of different levels of soybean cyst nematode in 1992. Plots were planted again in 1993 with the two cultivars in sequences that included Hartwig following Hartwig or Deltapine 105, and Deltapine 105 following Hartwig or Deltapine 105. The yield of Hartwig was inferior to Deltapine 105 at low population densities of H. glycines, but Hartwig yielded more than Deltapine 105 at high population densities. Hartwig was effective in suppressing H. glycines population density compared to susceptible Deltapine 105. The seed yield of Hartwig following Deltapine 105 or Hartwig, and Deltapine 105 following Hartwig yielded more than Deltapine 105 grown for 2 years.
crop loss; damage function; Glycine max; Heterodera glycines; host plant resistance; nematode; plant disease loss; soybean; soybean cyst nematode
The reproductive and damage potential of the reniform nematode, Rotylenchulus reniformis, on five cotton breeding lines reported as tolerant to this nematode in Texas were compared with two standard cotton cultivars, Deltapine 50 and Stoneville LA 887, in a North Carolina field naturally infested with R. reniformis. Numbers of R. reniformis in soil were suppressed at mid-season, and cotton-lint yield was increased by preplant fumigation with 1,3-dichloropropene. Population densities of R. reniformis at cotton harvest were unaffected by fumigation in 1998, but were affected in 1999. Some of the putatively tolerant breeding lines supported lower levels of R. reniformis and had higher tolerance indices to reniform nematode than the standard cultivars, but the yields of the breeding lines were significantly lower than the standard cultivars. Fumigation resulted in a 100- to 200-kg/ha increase in cotton lint yield for cultivars LA 887 and Deltapine 50.
cotton; crop loss; Gossypium hirsutum; host-plant resistance; nematode; plant disease loss; reniform nematode Rotylenchulus reniformis; tolerance
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.
Alfalfa; Allium cepa; almond; Aphelenchoides besseyi; Apium graveolens; apple; Arachis hypogaea; avocado; banana; Belonolaimus longicaudatus; blueberry; Brassicaceae; Brassica oleracea; Capsicum frutescens; Carica papaya; carrot; carrot cyst nematode; Carya illinoensis; cauliflower; celery; cherry; citrus; Citrus spp.; citrus nematode; Coffea arabica; coffee; Colocasia esculenta; Columbia lance nematode; corn; corn cyst nematode; crop loss; dagger nematode; Daucus carota; distribution; Ficus carica; fig; Fragaria × ananassa; Globodera tabacum; Glycine max; Gossypium hirsutum; guava; Helicotylenchus; Heterodera carotae; Heterodera glycines; Heterodera goettingiana; Heterodera schachtii; Heterodera zeae; Hoplolaimus columbus; Hoplolaimus galeatus; Ipomea batatas; Irish potato; Javanese root-knot nematode; Juglans sp.; Lactuca sativa; lance nematode; lettuce; Longidorus africanus; Longidorus breviannulatus; Lycopersicon esculentum; Macadamia integrifolia; macadamia nut; Malus sylvestris; Medicago sativa; Meloidogyne arenaria; Meloidogyne chitwoodi; Meloidogyne hapla; Meloidogyne incognita; Meloidogyne javanica; Meloidogyne nataliei; Mesocriconema ornata; Mesocriconema xenoplax; Musa paradisiaca; nectarine; needle nematode; nematode; Nicotiana tabacum; northern root-knot nematode; Olea europa; olive; papaya; pear; peach; pecan; Paratrichodorus allius; Paratrichodorus minor; peanut root-knot nematode; Persea americana; Persea gramtissima; Pistachia vera; pistachio; plant disease loss; Psidium guajava; Pratylenchus brachyurus; Pratylenchus coffeae; Pratylenchus neglectus; Pratylenchus penetrans; Pratylenchus thornei; Pratylenchus vulnus; prune; Prunus amygdalus; Prunus avium; Prunus persica; Quinisulcius acutus; raspberry; reniform nematode; resistance; rice; root-knot nematode; Rotylenchulus reniformis; Rubus spp.; Saccarhum officinarum; soybean cyst nematode; spiral nematode; strawberry; stubby root nematode; sting nematode; stunt nematode; Solanaceae; Solanum tuberosum; sorghum; Sorghum vulgare; southern root-knot nematode; sugar beet cyst nematode; sugar cane; sweetpotato; taro; tobacco cyst nematode; Trichodorus allius; Triticum aestivum; Tylenchorhynchus; Tylenchulus semipenetrans; Vaccinium; walnut; Zea mays; wheat; white-tip nematode; Xiphinema americanum; Xiphinema index; Xiphinema pachtaicum
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.
Distribution; Glycine max; Helicotylenchus; Heterodera glycines; Hoplolaimus columbus; Hoplolaimus galeatus; host race; Meloidogyne incognita; Mesocriconema; nematode; Paratrichodorus; populations; Pratylenchus; race; soybean; soybean cyst nematode; survey; Tylenchorhynchus; Xiphinema
Field experiments were conducted to determine peanut growth and yield responses to selected fumigant and nonfumigant nemaficide treatments in 1988 and 1989. All treatments with the fumigant 1, 3-D significantly suppressed nematode reproduction (Meloidogyne arenaria, M. hapla, and Mesocriconema ornatum) and enhanced peanut yields over the other treatments in four tests in 1988. Yield increases with the fumigant ranged from about 20% to 100% over the untreated control. Test sites in 1989 had lower nematode levels than those for 1988, and fewer positive plant and nematode responses were detected. Treatments with 1,3-D improved peanut quality but not yield in one experiment with low levels of M. hapla and M. ornatum in 1988. The 1,3-D + chloropicrin treatments at another site gave higher peanut yields than 1,3-D alone.
Arachis hypogaea; chemical control; management; Meloidogyne arenaria; Meloidogyne hapla; Mesocriconeraa ornatum; nematicides; nematode; peanut
The effects of soil type and initial inoculum density (Pi) on the reproductive and damage potentials of Meloidogyne incognita and Rotylenchulus reniformis on cotton were evaluated in microplot experiments from 1991 to 1993. The equilibrium nematode population density for R. reniformis on cotton was much greater than that of M. incognita, indicating that cotton is a better host for R. reniformis than M. incognita. Reproduction of M. incognita was greater in coarse-textured soils than in fine-textured soils, whereas R. reniformis reproduction was greatest in a Portsmouth loamy sand with intermediate percentages of clay plus silt. Population densities of M. incognita were inversely related to the percentage of silt and clay, but R. reniformis was favored by moderate levels of clay plus silt (ca. 28%). Both M. incognita races 3 and 4 and R. reniformis effected suppression of seed-cotton yield in all soil types evaluated. Cotton-yield suppression was greatest in response to R. reniformis at high Pi. Cotton maturity, measured as percentage of open bolls at different dates, was affected by the presence of nematodes in all 3 years.
cotton; ecology; edaphic factor; Gossypium hirsutum; Meloidogyne incognita; nematode; plant-disease loss; reniform nematode; root-knot nematode; Rotylenchulus reniformis; soil texture; yield
Selected soybean genotypes were evaluated for resistance to North Carolina populations of the soybean cyst nematode Heterodera glycines, the root-knot nematodes Meloidogyne incognita races 3 and 4, M. arenaria races 1 and 2, M. javanica, and the reniform nematode Rotylenchulus reniformis in two greenhouse tests. Populations of cyst nematode used in the first test were cultures from field samples originally classified as races 1-5, and those used in the second test included inbred cyst lines that corresponded to races 1, 3, and 4. The original race classification of some cyst populations shifted after repeated culture on susceptible 'Lee 68' soybean. Most of the cyst-resistant soybean cultivars tested were susceptible to M. arenaria and M. javanica. Exceptionally large galls were induced by M. arenaria on roots of Asgrow 5979, Hartwig, and CNS soybean. Hartwig soybean and PI 437654 were resistant to all cultured field populations of cyst nematodes in a first greenhouse test. In the second test, cyst indices of 11.3% and 19.4% were observed on roots of PI 437654 and Hartwig, respectively, when infected with an inbred line (OP50) of H. glycines corresponding to race 4. The cyst-resistant soybean germplasm tested, including Hartwig and PI 437654, supported only low numbers of reniform nematodes. The most severe soybean root necrosis observed, however, was associated with reniform nematode infection.
Glycine max; Heterodera glycines; Meloidogyne incognita; M. arenaria; M. javanica; reniform nematode; resistance; root-knot nematode; Rotylenchulus reniformis; soybean; soybean cyst nematode
Aldicarb, ethoprop, and fenamiphos were evaluated for their efficacy in controlling various species of root-knot nematodes on flue-cured tobacco and for their residual activity, as determined through periodic sampling and bioassays of soil taken from field plots. Field experiments were conducted at five locations over 2 years with flue-cured tobacco. Soil in plots treated with nematicides were formed into high, wide beds before transplanting with 'Coker 371-Gold' or 'K 326' tobacco. Residual control of Meloidogyne spp. was greatest (P ≤ 0.05) with fenamiphos (in some cases up to 10 weeks, as measured in tomato bioassays of infested soil and root fragments). Suppression of nematode reproduction by ethoprop was short-lived, and numbers of second-stage juveniles + eggs and numbers of galls in bioassays sometimes surpassed those of untreated plots within 4 weeks after treatment. Aldicarb gave intermediate control over time as compared to the other compounds. Although nematicidal efficacy of all compounds varied with site and season, fenamiphos and aldicarb generally produced the highest yields.
chemical control; Meloidogyne arenaria; M. incognita; M. javanica; nematode management; population dynamics; root-knot nematode; nernaticide; nematode; tobacco
The effects of soil types and soil water matric pressure on the Heterodera glycines-Glycine max interaction were examined in microplots in 1988 and 1989. Reproduction of H. glycines was restricted in fine-textured soils as compared with coarse-textured ones. Final population densities of this pathogen in both years of the study were greater in nonirrigated soils than in irrigated soils. The net photosynthetic rate of soybean (per unit area of leaf) was suppressed only slightly or not at all in response to infection by H. glycines and other stresses. Relative soybean-yield suppression in response to H. glycines was not affected by water content in fine-textured soils, but slopes of the damage functions were steepest in sand, sandy loam, and muck soils at high water content (irrigated plots). Yield restriction of soybean in response to this pathogen under irrigation was equal to or greater than the yield suppression under dry conditions. Although yield potential may be elevated by irrigation when soil-water content is inadequate, supplemental irrigation cannot be used to circumvent nematode damage to soybean.
Damage function; ecology; edaphic factors; Glycine max; Heterodera glycines; irrigation; photosynthesis; soil moisture; soil texture; soil water matric pressure; soybean; soybean cyst nematode
The soybean cultivars 'Braxton' and 'Kirby' were less susceptible to both races 1 and 2 of Meloidogyne arenaria than 'Centennial' and 'Young', which were highly susceptible. Soybean seed yields of resistant cultivars were greater (P = 0.05) than susceptible cultivars. Reproduction of M. arenaria races 1 and 2 was significantly lower on less susceptible cultivars compared to highly susceptible cultivars. Root galling, caused by M. arenaria, was 5-10 times greater on Centennial and Young than on less susceptible cultivars Kirby and Braxton. Resistance was independent of the host race of M. arenaria used in this study. Populations of M. arenaria that are highly pathogenic to soybean should be used in screening for soybean resistance rather than specific host races.
Glycine max; Meloidogyne arenaria; nematode; resistance; root-knot nematode; soybean
The reproductive potential and damage functions for Meloidogyne hapla and M. arenaria race 1 on Virginia-type peanuts (Arachis hypogaea cv. Florigiant) were determined over 2 years in microplot experiments in North Carolina. Peanut yield suppression and damage to pods as a result of galling were greatest in response to M. arenaria (P = 0.01). Damage functions for the two species were adequately described by the quadratic models: yield (g/plot) = 398 - 17.1 (log₁₀[Pi + 1]) - 17.0(log₁₀[Pi + 1])²; (R² = 0.83, P = 0.0001) for M. arenaria; and yield = 388 - 10.2(log₁₀[Pi + 1]) - 7.5(log₁₀[Pi + 1])², (R² = 0.30, P = 0.0001) for M. hapla. Both species caused galling on pods, but this was more severe in response to M. arenaria. Reproduction of M. arenaria race 1 was greater than M. hapla on peanut, which accounts in part for the more severe pod galling. Peanut was an excellent host for both M. arenaria race 1 and for M. hapla, but reproduction by M. hapla was more variable.
Arachis hypogaea; damage function; Meloidogyne arenaria; Meloidogyne hapla; nematode; peanut; reproductive potential; root-knot nematode
Alternate planting dates and periodic destruction of the previous year's soybean crop as well as 1-year bare fallow were used to establish a range of population densities ofHeterodera glycines for the subsequent year. Soybean cultivar Coker 156 (susceptible, moderately tolerant) was compared to cultivars Essex (susceptible, intolerant) and Bedford (resistant) to evaluate tolerance at different H. glycines population densities established through the previous year's treatments. Yield of Coker 156 was consistently intermediate between yields of Bedford and Essex in 1986 and 1987. Yield of Essex was negatively correlated (P = 0.05) with preplant egg numbers of H. glycines in 1987, whereas yield of Bedford and Coker 156 were not related to nematode density. Reproduction of H. glycines was greater (P = 0.05) on the moderately tolerant Coker 156 than on either of the other cultivars.
Glycine max; Heterodera glycines; nematode; soybean; soybean cyst nematode; tolerance
Eggs of Meloidogyne arenaria race 1 were encapsulated in calcium alginate for use as inoculum to infest peanut field plots. Some eggs within the capsules remained viable up to 10 weeks after preparation. A field site was successfully infested at peanut planting and (or) 6 weeks later. Dual applications of nematode inoculum (at planting and 6 weeks later) were superior to single applications (at planting or 6 weeks after planting). Field-site infestation levels at the end of the first year were related to the amount of inoculum dispersed and timing of the infestation (P = 0.001). Peanut yield was only slightly affected in the first year, but significant (P = 0.02) yield suppression occurred during the second year after field infestations. The negative relationship between the numbers of M. arenaria eggs and juveniles per 500 cm³ soil in the fall and the percentage of peanut hull galled the second year was described by a quadratic model (P = 0.002, R² = 0.41).
Arachis hypogaea; damage threshold; infestation technique; Meloidogyne arenaria; nematode; peanut; root-knot nematode
The first phase of this study involved repeated samplings of five fields using composite samples of 10, 20, 40, and 80 soil cores, to determine the precision of nematode assays. The second phase focused on randomly selecting two and four 2-ha subunits (data on Meloidogyne spp.) of 24 fields ranging from 6 to 40 ha and computing the precision of estimated means for these numbers ofsubunits versus the general field mean (based on all 2-ha subunits). Average numbers of nematodes from most samples containing Meloidogyne spp., Heterodera glycines, Helicotylenchus dihystera, Scutellonema brachyurum, and (or) Hoplolaimus galeatus were within 50% of the overall means. Coefficient of variation (CV) values were generally lower for 40 cores than for 10, 20, and 80 cores per sample. When data for all nematodes and fields were combined, this value was lowest for 40 and 80 cores. The CV values were higher for Meloidogyne spp. than for H. glycines. Means of two samplings increased the probability of obtaining numbers nearer the mean for that field than numbers from a single composite sample. For the second phase, population estimates of Meloidogyne spp. based on four 2-ha subunits generally were closer to field means than were those for two subunits. Sampling precision with these subunits diminished greatly in large fields with variable soils and (or) mixed cropping histories. Either two or four subunits gave population estimates within 3-20% of the field mean in most instances. The mean man hours required for sampling ca. 2-ha parcels of 4-20-ha fields was 0.54 hours.
assay; Criconemella spp.; Helicotylenchus dihystera; Heterodera glycines; Meloidogyne; ring nematode; root-knot nematode; sampling; Scutellonema brachyurum; soybean cyst nematode; spiral nematode
The influence of soil texture on Soybean yield in the presence of Heterodera glycines was investigated by comparing yields of susceptible cultivars with a resistant cultivar for 2 years. Soybean yield was negatively correlated with increasing sand content (P = 0.05). Yields of susceptible cultivars were suppressed with increasing sand content. Final nematode population densities were lowest in plots with greatest sand content. Soybean infection by SCN, as determined by the number of cysts 30 days after planting, was not consistently related to soil texture over 2 years. Initial nematode population density was positively related to soybean yield the first year and negatively related to soybean yield the second, probably a result of greater yield suppression by H. glycines in plots with greater sand content.
crop loss; Heterodera glycines; Glycine max; soil texture
A series of greenhouse, phytotron, field, and microplot experiments evaluated factors that influenced plant-growth.stimulation associated with the use of the pesticide aldicarb. A phytotron experiment showed.that aldicarb increased growth, of Ransom soybean at all temperatures but was somewhat phytotoxic to Coker 156 soybean at 30 C. Soybean gave the greatest response to this nematicide at 22 C in a commercially available medium, Metromix 220. Soybean cultivars Ransom and Coker 156. exhibited increased growth in response to aldicarb or, to a lesser extent aldicarb sulfone treatments under greenhouse and microplot conditions. Enhanced soybean growth, however, did not always result in significantly greater soybean seed yield. Soil type affected soybean sensitivity to aldicarb, with. the greatest growth and yield increases generally occurring in fine-textured soils or those with high.organic matter. Plant-growth stimulation by aldicarb occurs in the absence of pests but is dependent upon concentration and edaphic and other environmental factors.
atdicarb; aldicarb sulfone; Glycine max; growth regulation nematicide; Temik
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
anhydrobiosis; callus tissue; culturing; Glycine max; lesion nematode; Pratylenchus brachyurus; soybean
Seven soybeans were selected from 200 entries evaluated for tolerance to soybean cyst nematode (SCN), Heterodera glycines. Tolerance to SCN was measured by comparing the seed yield from aldicarb-treated vs. nontreated plots. A yield response index (YRI) was calculated for each entry: YRI = (seed yield from nontreated plot/seed yield from treated plot) × 100. The soybean entries Coker 156, PI 97100, and S79-8059 exhibited high tolerance (YRI) to SCN when compared to Essex even though they became heavily infected with SCN. Tolerance in soybeans to SCN may be useful in pest management programs designed to stabilize soybean yield.
Glycine max; Heterodera glycines; pest management; resistance; SCN; soybean; soybean cyst nematode; tolerance