Progress 10/01/99 to 09/30/04
Outputs
Field experiments were conducted each year of the project to determine whether the soybean cyst nematode (SCN), Heterodera glycines, was capable of reproducing on soybean roots after the tops of the soybean plants were removed. Experiments consisted of 1- to 4-row-long experimental plots planted with an SCN-susceptible soybean variety in an SCN-infested field. Soil samples (ten soil cores from arbitrarily selected locations near and on either side of the crop row) were collected from each plot in the fall of each year and then again in the spring. SCN cysts were extracted from a subsample of each soil sample and counted, then eggs were extracted from cysts and counted to assess potential reproduction of SCN in fields even after soybeans have been harvested. In general, SCN population densities increased slightly from fall to spring in many plots over many winters.
Impacts
The results of this research indicate that population densities of the soybean cyst nematode increase in fields where soybeans are grown even after the soybean crop has been harvested. The biological basis of this increase is not yet understood.
Publications
- Paz, J.O., W.D. Batchelor, and G.L. Tylka. 2001. Method to use crop growth models to estimate potential return for variable-rate management in soybeans. Transactions of the American Society of Agricultural Engineers 44:1335-1341.
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Progress 01/01/03 to 12/31/03
Outputs
A field experiment was conducted in 2002/2003 at the Iowa State University Burkey Research Farm to determine whether the soybean cyst nematode (SCN), Heterodera glycines, was capable of reproducing on soybean roots after the tops of the soybean plants were removed. Four-row, 5.2-m-long experimental plots were planted with an SCN-susceptible soybean variety in an SCN-infested field in 2002. There were four treatments randomly assigned to the replicated plots: 1) removal of soybean plants in August, 2) removal of soybean plants in October (at harvest), 3) removal of soybean plants in early December, and 4) plots left unplanted and fallow. Soil samples (ten 2.5-cm diameter soil cores from arbitrarily selected locations within 15 cm of and on either side of the crop row) were collected from the center two rows of each plot each time soybean plants were removed from any of the treatments (in August, October, and December 2002) and again in April of 2003. SCN cysts were
extracted from a subsample of each soil sample and counted, then eggs were extracted from cysts and counted to assess potential reproduction of SCN in fields even after soybeans have been harvested. In the plots that were planted with soybeans and the tops of the plants were removed in August, SCN continued to develop and reproduce (increase in numbers) through October, but not after that. And in general, SCN population densities increased slightly from December 2002 to April 2003 in most of the experimental plots. The results of this research indicate that population densities of the soybean cyst nematode increase in fields where soybeans are grown even after the soybean crop has been harvested. The biological basis of this increase is not apparent.
Impacts
Specific information about the change in soybean cyst nematode population densities during the period from fall harvest to spring planting the next growing season will help soybean growers and crop consultants and advisors better understand soybean cyst nematode population dynamics and to make better decisions on whether to use resistant soybean varieties or rotate to nonhost crops such as corn for management of this pest.
Publications
- Tabor, G.M., G.L. Tylka, S.C. Cianzio, and C.R. Bronson. 2003. Resistance to Phialophora gregata is expressed in the stems of resistant soybeans. Plant Disease 87:970-976.
- Tabor, G.M., G.L. Tylka, J.E. Behm, and C.R. Bronson. 2003. Heterodera glycines infection increases incidence and severity of brown stem rot of soybeans. Plant Disease 87:655-661.
- Tylka, G.L, G.D. Gebhart, and C.C. Marett. 2003. Iowa 2002 soybean cyst nematode-resistant soybean variety trial results. Online. Crop Management (http://www.plantmanagementnetwork.org/pub/cm/trials/2002/soy/Tylka.x ls).
- Tylka, G.L, G.D. Gebhart, and C.C. Marett. 2003. Iowa 2001 soybean cyst nematode-resistant soybean variety trial results. Online. Crop Management (http://www.plantmanagementnetwork.org/pub/cm/trials/2001/soy/Tylka.x ls).
- Tylka, G.L. 2003. Soybean cyst nematode-resistant soybean varieties for Iowa. Iowa State University Cooperative Extension Service, Publication Pm-1649, 20 pp.
- Tylka, G.L., G.D. Gebhart, and C.C. Marett. 2003. Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa-2002. Iowa State University Cooperative Extension Service, Publication IPM 52, 17 pp.
- Wang, J., T.L. Niblack, J.N. Tremaine, W.J. Wiebold, G.L. Tylka, C.C. Marett, G.R. Noel, O. Myers, O., and M.E. Schmidt. 2003. The soybean cyst nematode reduces soybean yield without causing obvious symptoms. Plant Disease 87:623-628.
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Progress 01/01/02 to 12/31/02
Outputs
A field experiment was conducted for the second time in 2001/2002 at the Bruner Research Farm to determine whether the soybean cyst nematode (SCN), Heterodera glycines, was capable of reproducing on soybean roots after soybean harvest in Iowa. Four-row, 5.2-m-long experimental plots were designated in a field planted with an SCN-susceptible soybean variety in 2001. There were three treatments randomly assigned to the replicated plots: 1) removal of soybean plants in August, 2) removal of soybean plants in October (at harvest), and removal of soybean plants in early December. Soil samples (ten 2.5-cm diameter soil cores from arbitrarily selected locations within 15 cm of and on either side of the crop row) were collected from the center two rows of each plot each time soybean plants were removed from any of the three treatments (in August, October, and December). SCN cysts were extracted from a subsample of each soil sample and counted, then eggs were extracted from
cysts and counted to assess potential reproduction of SCN in fields even after soybeans have been harvested. Results of the experiment indicate that SCN continues to develop and reproduce (increase in numbers) even after the soybean plants are fully mature. Additionally, SCN population densities increased from December 2001 to April 2002 in some of the experimental plots.
Impacts
The results of this research indicate that population densities of the soybean cyst nematode increase in fields where soybeans are grown even after the soybean crop has been harvested. Consequently, soil samples should be collected in the spring, prior to the planting of the crop, to most accurately determine the magnitude of an infestation of this nematode.
Publications
- Fallick JB, WD Batchelor, GL Tylka, TL Niblack and JO Paz. 2002. Coupling soybean cyst nematode damage to CROPGRO-Soybean. Transactions of the American Society of Agricultural Engineers 45:433-441.
- Niblack TL, RD Riggs, PR Arelli, GR Noel, CH Opperman, JH Orf, DP Schmitt, JG Shannon and GL Tylka. 2002. A new classification scheme for genetically diverse populations of Heterodera glycines. Journal of Nematology 34:279-288.
- Nutter FW, GL Tylka, J Guan, AJD Moreira, CC Marett, TR Rosburg, JP Basart and CS Chong. 2002. Use of remote sensing to detect soybean cyst nematode-induced plant stress. Journal of Nematology 34:222-231.
- Perry RN, J Beane, CC Marett and GL Tylka. 2002. Comparison of the rate of embryonic development of Globodera rostochiensis and G. pallida using flow cytometric analysis. Nematology 4:553-555.
- Tylka GL. 2002. Soybean cyst nematode-resistant soybean varieties for Iowa. Iowa State University Cooperative Extension Service, Publication Pm-1649, 20 pp.
- Tylka GL, GD Gebhart and CC Marett. 2002. Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa ? 2002. Iowa State University Cooperative Extension Service, Publication IPM?52, 20 pp.
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Progress 01/01/01 to 12/31/01
Outputs
A field experiment was conducted to assess the overwinter survival of the soybean cyst nematode (SCN), Heterodera glycines, in Iowa. The experiment was conducted at the Iowa State University Bruner Research Farm located west of Ames, Iowa. Plots (2 m long and 20 cm wide with the long axis centered over the crop row) were established in a field infested with SCN in which soybeans were grown in 2000. In the fall of 2000 (after soybean harvest), and again in the spring of 2001 (before planting), ten soil cores were collected from arbitrarily selected locations within 15 cm of and on either side of the crop row. The plots were undisturbed over winter and between sample collection dates. SCN cysts were extracted from a subsample of each soil sample, and then eggs were extracted from cysts and counted using a dissecting microscope. SCN egg population densities were less in the spring 2001 samples than in the fall 2000 samples in many, but not all, plots. To determine
whether SCN was reproducing on soybean roots after soybean harvest, a second field experiment was initiated in 2001 at the Bruner Research Farm. Four-row, 5.2-m-long experimental plots were designated in a field planted with an SCN-susceptible soybean variety. There were three treatments randomly assigned to the plots: 1) removal of soybean plants in August, 2) removal of soybean plants in October (at harvest), and removal of soybean plants in early December. Soil samples (as done for the earlier experiment) were collected from the center two rows of each plot each time soybean plants were removed from any set of treatments (in August, October, and December). SCN cysts will be extracted from a subsample of each soil sample and counted, then eggs will be extracted from cysts and counted using a dissecting microscope to assess potential reproduction of SCN in fields even after soybeans have been harvested. All of the soil samples have not yet been processed for this experiment;
consequently no conclusions can be drawn about the research at this time.
Impacts
The results of this research indicate that population densities of the soybean cyst nematode increase in fields where soybeans are grown even after the soybean crop has been harvested. Consequently, soil samples should be collected in the spring, prior to the planting of the crop, to most accurately determine the magnitude of an infestation of this nematode.
Publications
- Fallick JB, WD Batchelor, GL Tylka and TL Niblack. 2000. Coupling soybean cyst nematode damage to CROPGRO-Soybean. Transactions of the American Society of Agricultural Engineers (in press).
- Gavassoni WL, GL Tylka and GP Munkvold. 2001. Relationship between tillage and spatial patterns of Heterodera glycines. Phytopathology 91:534-545.
- Paz JO, WD Batchelor, GL Tylka and RG Hartzler. 2001. A modeling approach to quantify the effects of spatial soybean yield-limiting factors. Transactions of the American Society of Agricultural Engineers 44(5):1329-1334.
- Paz JO, WD Batchelor and GL Tylka. 2001. Estimating potential economic return for variable rate management in soybeans. Transactions of the American Society of Agricultural Engineers (accepted).
- Tylka GL and CA Jasalavich. 2001. Free-living and plant-parasitic nematodes (roundworms). The Plant Health Instructor. DOI: 10.1094/PHI-K-2001-0409-01
- Tylka GL, GD Gebhart and CC Marett. 2001. Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa - 2001. Iowa State University Cooperative Extension Service, Publication IPM?52, 20 pp.
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Progress 01/01/00 to 12/31/00
Outputs
Two separate experiments were conducted to assess the over winter survival of the soybean cyst nematode (SCN), Heterodera glycines, in Iowa. Plots in both experiments were 2 m long, 20 cm wide, with the long axis centered over the crop row. In one experiment, plots were established over rows of soybeans grown in the 1999 season. In the other experiment, plots were established over rows of corn grown in 1999. In both experiments, ten soil cores were collected from arbitrarily selected locations within 15 cm of and on either side of the crop row on November 8 and 22, December 7 and 30, 1999, January 12, March 8 and 31, 2000. The plots were left undisturbed after harvest 1999 and until after the last samples were collected at the end of March 2000. SCN cysts were extracted from a subsample of each soil sample, then eggs were extracted from cysts and counted using a dissecting microscope. SCN egg population densities were less in the spring 2000 samples than in the fall
1999 samples in many plots. This result was in contrast to results obtained in previous years of the study. In some plots, SCN population densities were the same in the spring 2000 samples as they were in the fall 1999 samples. In general, SCN densities decreased over the 1999/2000 winter period in most plots, regardless of the previous crop grown. In some plots that had soybeans grown in them in 1999, SCN population densities increased after harvest until January 2000.
Impacts
The results of this research indicate that population densities of the soybean cyst nematode increase in fields where soybeans are grown even after the soybean crop has been harvested. Consequently, soil samples should be collected in the spring, prior to the planting of the crop, to most accurately determine the magnitude of an infestation of this nematode.
Publications
- Wang J, PA Donald, TL Niblack, GW Bird, J Faghihi, JM Ferris, DJ Jardine, C Grau, PE Lipps, AE MacGuidwin, H Melakeberhan, GR Noel, P Pierson, RM Reidel, PR Sellers, WC Stienstra, TC Todd, GL Tylka and DS Wysong. 2000. Soybean cyst nematode reproduction in the north central United States. Plant Disease 84:77-82.
- Buckelew LD, LP Pedigo, HM Mero, MDK Owen and GL Tylka. 2000. Effects of weed management systems on canopy insects in herbicide-resistant soybeans. Journal of Economic Entomology 93:1437-1443.
- Davis EL and GL Tylka. 2000. Soybean cyst nematode disease. Plant Health Instructor. DOI: 10.1094/PHI-I-2000-0725-01
- Fallick JB, WD Batchelor, GL Tylka and TL Niblack. 2000. Coupling soybean cyst nematode damage to CROPGRO-Soybean. Transactions of the American Society of Agricultural Engineers (accepted for publication).
- Gavassoni WL, GL Tylka and GP Munkvold. 2000. Relationship between tillage and spatial patterns of Heterodera glycines. Phytopathology (accepted for publication).
- Tylka GL. 2000. Soybean cyst nematode race test: do you really need one? Proceedings of the 2000 Iowa State University Integrated Crop Management Conference, pp. 1-8.
- Tylka GL, GD Gebhart and CC Marett. 2000. Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa - 2000. Iowa State University Cooperative Extension Service, Publication IPM-52, 12 pp.
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Progress 01/01/99 to 12/31/99
Outputs
A small-scale field experiment was conducted in eastern Boone County, near Ames, Iowa, with replicate plots planted with corn or soybean in 1998. Soil cores were collected from each plot in October 1998 (after harvest) and in April 1999 (prior to planting). During 1999, corn was grown in the 1998 soybean plots and soybeans were grown in the 1998 corn plots. Soil cores again were collected from all plots at the time of harvest in October 1999, then every two weeks thereafter until early January 2000. Soybean cyst nematode (SCN) egg population densities were determined from each soil sample taken at each sampling date. Changes in SCN egg population densities over the 1998/1999 winter period were calculated from the SCN egg densities detected in the soil samples. As in previous years, SCN egg population densities were greater in the spring 1999 samples than in the fall 1998 samples in most plots. However, SCN population densities were the same in the spring 1999 samples
and the fall 1998 samples in some plots. Nematode densities decreased over the 1998/1999 winter period in only a few plots. In plots that had soybeans grown in them in 1999, SCN population densities steadily increased after harvest until January 2000. In contrast, nematode numbers were static or declined slightly from October 1999 to January 2000 in plots where corn was grown in 1999.
Impacts
(N/A)
Publications
- Tylka GL and Flynn PH. 1999. Interpreting SCN soil sample results. Iowa State University Cooperative Extension Service, Publication IPM61, 4 pp.
- Tylka GL, Souhrada SK and Marett CC. 1999. Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa 1998. Iowa State University Cooperative Extension Service, Publication IPM52, 12 pp.
- Workneh F, Yang XB and Tylka GL. 1999. Soybean brown stem rot, Phytophthora sojae, and Heterodera glycines affected by soil texture and tillage relations. Phytopathology 89:844-850.
- Workneh F, Tylka GL, Yang XB, Faghihi J and Ferris JM. 1999. Assessment of soybean brown stem rot, Phytophthora sojae, and Heterodera glycines in the northcentral United States using area-frame sampling: prevalence and effects of tillage. Phytopathology 89:204-211.
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Progress 01/01/98 to 12/31/98
Outputs
Two 20.2-hectare study areas were established in nearby fields in southern Boone County, Iowa in 1997; one field was planted with corn and the other with soybean in 1997. The study areas were divided into 100 0.2-hectare cells, and 20 soil cores were collected from within a 3-meter radius around a randomly selected point within each cell after the 1997 harvest and again prior to planting in 1998. Soybean cyst nematode (SCN) egg population densities were determined from each soil sample taken at each sampling date. Changes in SCN egg population densities over the 1997/1998 winter period were calculated from the SCN egg densities detected in the soil samples. Additionally, a small-scale field experiment was conducted in eastern Boone County, near Ames, Iowa, with replicate plots planted with corn or soybean in 1997. Soil cores were collected from each plot after the 1997 harvest and prior to planting in 1998. Soybean cyst nematode (SCN) egg population densities were
determined from each soil sample taken at each sampling date. Changes in SCN egg population densities over the 1997/1998 winter period were calculated from the SCN egg densities detected in the soil samples. In most of the plots in all three of the experiments, SCN egg population densities were greater in the spring 1998 samples than in the fall 1997 samples. In some of the plots, SCN population densities were the same in the spring 1998 samples and the fall 1997 samples. Nematode densities decreased over the 1997/1998 winter period in very few plots. The basis for the increase in SCN population densities from the time of the fall sampling to the spring sampling is unknown, but this phenomenon has been observed for several years in Iowa and other Midwestern states.
Impacts
(N/A)
Publications
- Levene, B.C., M.D.K. Owen, and G.L. Tylka. 1998. Influence of herbicide application to soybean on soybean cyst nematode egg hatching. Journal of Nematology 30:347-352.
- Levene, B.C., M.D.K. Owen, and G.L. Tylka. 1998. Response of soybean cyst nematodes and soybeans to post herbicides. Weed Science 46:263-270.
- Workneh, F., X.B. Yang, and G.L. Tylka. 1998. Effect of tillage practices on vertical distribution of Phytophthora sojae. Plant Disease 82:1258-1263.
- Jones, P.W., G.L. Tylka, and R.N. Perry. 1998. Chapter 8, Hatching in Physiology and Biochemistry of Free-living and Plant-parasitic Nematodes. R.N. Perry and D.J. Wright, eds. CAB International, Oxon, United Kingdom.
- Tylka, G.L. 1998. Soybean cyst nematode; picking your pockets. Proceedings of the Fifth Annual Southwest Agricultural Conference (Ontario, Canada), pp. 10-15.
- Tylka, G.L. 1998. Status of soybean cyst nematode in the Midwest in 1998. Proceedings of the Third Annual Midwest Soybean Conference, 5 pp.
- Tylka, G.L. 1998. Take the test, beat the pest: The SCN Coalition. Proceedings of the 1998 Iowa State University Integrated Crop Management Conference, pp. 129-132.
- Tylka, G.L. 1998. Soybean cyst nematode - biology and management. Proceedings of the 1998 Iowa State University Integrated Crop Management Conference, pp. 141-146.
- Tylka, G.L. 1998. Soybean cyst nematode - identification and extraction techniques. Proceedings of the 1998 Iowa State University Integrated Crop Management Conference, pp. 133-140.
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Progress 01/01/97 to 12/31/97
Outputs
Two 20.2-hectare study areas were established in nearby fields in southern Boone County, Iowa in 1996; one field was planted with corn and the other with soybean in 1996. The study areas were divided into 100 0.2-hectare cells, and 20 soil cores were collected from within a 3-meter radius around a randomly selected point within each cell after the 1996 harvest and prior to planting in 1997. Soybean cyst nematode (SCN) egg population densities were determined from each soil sample taken at each sampling date. Changes in SCN egg population densities over the 1996/1997 winter period were calculated from the SCN egg densities detected in the soil samples. In the field in which corn was grown in 1996, one third of the 0.2-hectare cells had greater SCN population densities in spring 1997 than in fall 1996. In contrast, two-thirds of the 0.2-hectare cells had greater SCN population densities in spring 1997 than in fall 1996 in the field in which soybean was grown in 1996.
The data indicate that the crop grown prior to the overwinter period may affect the overwinter survival of SCN populations in Iowa. The SCN produces eggs outside of its body in an egg mass as well as internally in the body cavity. The egg-filled body of the female eventually becomes a protective cyst. Laboratory research conducted during 1997 revealed that the eggs contained within the cysts of SCN exhibited less hatch in water than egg-mass eggs and were affected to a much greater extent than egg-mass eggs by the hatch stimulant, zinc sulfate, and by synthetic hatch inhibitors. The results from the field and laboratory research have provided new information concerning the ecology of this important soilborne soybean pathogen.
Impacts
(N/A)
Publications
- Thompson, J.M., and G.L. Tylka. 1997. Differences in hatching of Heterodera glycines egg-mass and encysted eggs in vitro. Journal of
- Levene, B.C., M.D.K. Owen, and G.L. Tylka. 1998. Influence of herbicide application to soybean on soybean cyst nematode egg hatching. Journal of Nematology (in press).
- Levene, B.C., M.D.K. Owen, and G.L. Tylka. 1998. Response of soybean cyst nematodes and soybeans to post herbicides. Weed Science (in
- Jones, P.W., G.L. Tylka, and R.N. Perry. 1998. Chapter 8, Hatching in Physiology and Biochemistry of Free-living and Plant-parasitic Nematodes. R.N. Perry and D.J. Wright, eds. CAB International, Oxon,
- Thompson, J.M. 1997. The effects of synthetic glycinoeclepin A analogs on hatching of Heterodera glycines. M.S. Thesis. 47 pp.
- Marett, C.C. 1997. Studies on the effects of synthetic glycinoeclepin A analogs on hatching of Globodera, Heterodera, and Rotylenchulus nematodes. M.S. Thesis. 74 pp.
- Behm, J.E. 1997. Soybean tolerance to soybean cyst nematode (Heterodera glycines Ichinohe), and interactions between H. glycines and Phialophora gregata, the causal agent of brown stem rot of soybean. Ph.D. Dissertation. 162 pp.
- Tylka, G.L. 1997. Soybean cyst nematode - biology and management. Proceedings of the 1997 Iowa State University Integrated Crop Management Conference, pp. 49-53.
- Tylka, G.L. 1997. Soybean cyst nematode - identification and extraction techniques. Proceedings of the 1997 Iowa State University Integrated Crop Management Conference, pp. 55-61.
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Progress 01/01/96 to 12/30/96
Outputs
Two field experiments were conducted, one with replicate plots planted with cornor soybean and the other with replicate plots planted with soybean in 1995. Soil cores were collected from each plot after the 1995 harvest and prior to planting in 1996. Soybean cyst nematode (SCN) egg population densities were determined from each soil sample taken at each sampling date. Changes in SCN egg population densities over the 1995/1996 winter period were calculated from the SCN egg densities detected in the soil samples. SCN egg population densities increased from fall 1995 to spring 1996 in most of the plots, and stayed the same in several others. SCN egg population densities decreased over the 1995/1996 winter period in very few plots. As was the case with data obtained from the previous year, high variability in egg population densities among treatments at both sampling dates in the experiment in which corn and soybeans had been grown in 1995 precluded detection of previous
crop treatment effects during the 1995/1996 winter. New research is planned to determine whether the detected increases in SCN egg population densities were due to reproduction of the nematode during the winter period or due to physical factors affecting physical movement of SCN cysts in the soil profile. Determining the reason for the detected increases in SCN population densities during winter periods is very important because it may indicate a need to recommend sampling of fields for SCN only in the spring.
Impacts
(N/A)
Publications
- Behm, J.E., G.L. Tylka, and S.R. Cianzio. 1996. Evaluations of soybean genotypes for tolerance to soybean cyst nematode. Phytopathology 86 (supplement):98.
- Gavassoni, W.L., G.P. Munkvold, and G.L. Tylka. 1996. Spatial difference of soybean cyst nematode cyst and egg populations. Phytopathology 86 (supplement):86.
- Tylka, G.L. 1996. Soybean cyst nematode - biology and management. Proceedings of the 1996 Iowa State University Integrated Crop Management Conference, pp. 127-1.
- Kraus, G.A., S. Vander Louw, G.L. Tylka, and D.H. Soh. 1996. The synthesis and testing of compounds that inhibit soybean cyst nematode egg hatch. Journal of Agricultural and Food Chemistry 44:1548-1550.
- Shapiro, D.I., G.L. Tylka, and L.C. Lewis. 1996. Effects of fertilizers on virulence of Steinernema carpocapsae. Applied Soil Ecology 3:27-34.
- Tylka, G.L. 1996. Soybean cyst nematode: what does it mean to the seed industry. Proceedings of the Eighteenth Annual Seed Technology Conference, Iowa State University, pp. 17-26.
- Marett, C.C., G.L. Tylka, and K.R. Harkins. 1996. Relationship between embryogeny and hatching of soybean cyst nematode eggs. Phytopathology 86 (supplement):98.
- Thompson, J.M. and G.L. Tylka. 1996. Comparison of hatching of soybean cyst nematode egg-mass eggs and encysted eggs. Phytopathology 86 (supplement):98.
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Progress 01/01/95 to 12/30/95
Outputs
A field experiment was conducted with plots located in 3 blocks planted with corn and 3 planted with soybeans in 1994. Treatments, replicated 4 times within each corn and soybean block, were chisel-till and no-till. Soil cores were collected from each plot after 1994 harvest and prior to 1995 planting, and soybean cyst nematode (SCN) egg densities were determined from each soil sample. Of the 24 plots, SCN egg densities decreased from fall 1994 to spring 1995 in 16 plots, increased in 7 plots, and were unchanged in 1 plot. High variability in egg densities within treatments at both sampling dates precluded detection of treatment effects. Microplots were planted with the susceptible soybean cultivars Corsoy79 (maturity group II) and Wright (maturity group VII) in another experiment. Eggs were collected from SCN adult females on roots in 4 microplots per cultivar every 10 days from May through September and were analyzed for embryological development. Plant phenology was
assessed when eggs were collected. Corsoy79 plants flowered sooner than those of Wright and ceased vegetative development 50 days after planting. Wright continued to produce new vegetative growth through the season and began flowering 50 days after Corsoy79. Despite differences in plant development, embryogeny of SCN eggs on the cultivars were similar. Embryogeny of eggs produced on Corsoy79 were significantly different from that on Wright at only 3 of 10 sampling dates, 2 of which were near the end of the experiment.
Impacts
(N/A)
Publications
- NO PUBLICATIONS REPORTED THIS PERIOD.
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Progress 01/01/94 to 12/30/94
Outputs
This project was initiated in 1994, and the first experiments were established in October and November. Consequently, there are no results to report.
Impacts
(N/A)
Publications
- NO PUBLICATIONS REPORTED THIS PERIOD.
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