Progress 10/01/99 to 08/31/04
Outputs
A goal of the Regional Cooperative Nematode Project NC-215 was to collect and evaluate data on the persistence in the soil of the soybean cyst nematode (SCN) and other nematode species important to the agriculture of the region. Indiana nematologists (Drs. Jamal Faghihi and V. Ferris) contributed to Objective 1 of the project to determine the effect of cultural factors on nematode attrition. Our contributions to this objective began in 1994, when we compared SCN egg counts from post-season soil samples with counts in the soil the following spring at the time of planting. We found, as did other researchers in the region, that early in this study egg counts increased 180 - 300%, especially during the winter of 1994 - 1995. To seek explanations a series of experimental modifications were undertaken during the next few years including the immediate processing of some aliquots of post-harvest samples, followed by spring processing of other aliquots. Also, several different
modes of storage were tried (mainly storage at different temperatures). In addition, soil cores from upper level cores were separated from lower-level cores, and percentages of diseased eggs were calculated in each instance. During the years of these experiments, although the numbers of eggs increased at some locations in the region and decreased at others, the percentage of diseased eggs did not vary in ways that suggested patterns. Storage temperatures of samples did not affect the numbers of females recovered, except that samples that were frozen during storage did have increased numbers of females when they were processed. We concluded that females/eggs of SCN populations in our region survived best in frozen soils. During this period, Dr. Faghihi developed in our laboratory a procedure for obtaining reproducible quantities of viable eggs and juveniles from cysts recovered from soils. This procedure has been adopted by the other laboratories of the north central region as the
standard method for producing inoculum for experiments.
Impacts
Nematologists are spread thinly over the north central region and a regional committee such as NC-215 is the only viable mechanism for meeting on a regular basis and tackling mutual problems in a way that increases the productivity of each laboratory. The adoption of the standardized method for production of inoculum that was developed in our laboratory is an excellent example of the fruits of such cooperative research.
Publications
- No publications reported this period
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Progress 10/01/02 to 09/30/03
Outputs
The current goal of the Regional Cooperative Nematode Project NC-215 is to collect and evaluate data on the persistence in the soil of Heterodera glycines (the soybean cyst nematode) and other nematode species important to the agriculture of the region. We (Drs. Jamal Faghihi and V. Ferris) contributed to Objective 1 of the project, to determine the impact of cultural factors on nematode attrition. In 250 cc soil samples collected in 2002 and processed in 2003, we found that mean spring densities of soybean cyst nematode (SCN) under soybean were greater in tilled than in no-till plots (3450 vs. 1275). In the fall samples, however, the situation reversed itself, with fewer eggs present in tilled than in no-till samples (2550 vs. 4500). SCN egg counts in rotation plots planted to oats in 2002 did not change over the season, but in rotation plots planted to corn, marked reduction in SCN egg count occurred during the season in both tilled and no-till plots. With respect
to SCN egg dormancy and egg viability, no differences could be discerned between eggs from soil of tilled and no-till plots. Fewer spiral nematodes were present in the soybean plots than in the previous year, but no marked differences could be associated with tillage. In the spring 2002 samples, lesion nematodes were present in all crops, but by fall they had disappeared from tilled and no-till plots under oats. This was a marked difference from the 2001 samples. Dagger nematodes were present only under corn in no-till plots, whereas the previous year they were present only under oats in tilled and no-till plots.
Impacts
By working together cooperatively, nematologists of the north central region can collect and analyze data important to the management of nematodes important to the agriculture of the entire region. This maximizes the productivity of these nematologists, despite the fact that they are few in number. Techniques for extraction of SCN developed in our laboratory were unanimously adopted by the other laboratories of the north central region as standard methods
Publications
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Progress 10/01/01 to 09/30/02
Outputs
The purpose of the ongoing Regional Cooperative Nematode Project NC-215 is to devise control tactics and programs that accelerate the attrition of established nematode populations. These control tactics must be based on a comprehensive understanding of the factors and timing of events responsible for nematode persistence in soils of the region. We are contributing to the first objective of the project, which is designed to determine the impact of cultural factors on nematode attrition. The field area that we use (selected last year) was previously a part of a tilled field infested with soybean cyst nematode (SCN) and planted to soybean prior to the start of the current study. The pre-plant soil samples (spring 2001) had shown much random variability in kinds and numbers of nematodes recovered. Soil samples taken following the first planting cycle of the new experiments, were processed following harvest, and the kinds and numbers of nematodes found were analyzed in
2002. As expected, these samples showed less random variability than had the pre-plant samples. With respect to eggs of soybean cyst nematode recovered, the numbers under soybeans were, predictably, much higher (4290 per sample) than under corn (390) or oats (960) in the tilled plots. Comparable numbers were found also under no till. Tests of egg dormancy and egg variability in samples taken from each of the plots showed no differences that could be attributed to host crop or tillage regime. Worm population densities of SCN and other plant parasitic nematode species showed some interesting differences: The SCN population was higher in the tilled plots than in the no-till plots, as was the case also for spiral nematodes. In both kinds of tillage plots, the numbers of lesion nematodes under oats were greatly increased over the pre-plant samples. Although no dagger nematodes had been recovered in any of the pre-plant samples, they were recovered under oats in the post-harvest samples
from both tillage regimes.
Impacts
It is essential to achieve a comprehensive understanding of factors affecting the presence and persistence of pest nematodes in the corn/soybean production systems of the north central region. Such understanding will lead to better management strategies. This group effort is the best way to maximize productivity of the few nematologists now working in the cooperating states.
Publications
- No publications reported this period
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Progress 10/01/00 to 09/30/01
Outputs
The new thrust of the Regional Cooperative Nematode Project NC-215 is to study the persistence in soils of the North Central Region of soybean cyst nematode (SCN) and other regionally important nematode species. The goal is to obtain sufficient data to be able to devise control tactics and programs which accelerate the attrition of established nematode populations based on a comprehensive understanding of the factors and timing of events responsible for nematode persistence. As part of the Indiana contribution to an area-wide rotation/tillage experiment that is part of the project, plots were established in a part of an SCN infested field that was tilled and planted to soybeans during the previous year. Prior to planting, four-250cc soil samples were processed from each new plot area as mandated by project guidelines, and counts were taken of SCN eggs recovered and also of other plant parasitic nematode species. Data for SCN egg dormancy and egg viability tests were
also collected using several methods. Plots were designated as either Till or No Till plots, and were planted to either corn, soybeans, or oats. All pre-plant counts were highly variable among replicates, owing to random distribution of nematodes in the soil. It is expected that during the course of these long-term experiments replicate variability will decline and the data will show effects attributable to crop rotation and/or tillage regime.
Impacts
The current North Central Cooperative Regional Project NC-215 recognizes the fact that nematodes, including soybean cyst nematode (SCN) and other nematodes as well, are chronic problems for corn/soybean production systems throughout the region. Crop rotation is part of all successful nematode management programs for field crops and a goal is to devise tactics and programs to accelerate the attrition of established nematode populations. To do this, a comprehensive understanding of the factors and timing of events in the soil is essential. A joint approach to common problems can maximize productivity for the few nematologists now working in the cooperating states.
Publications
- Donald, P.A., G. R. Noel, H. Melakerberhan, R. Riggs, N. Atibalentja, J. Faghihi, J. Ferris, G. Tylka, D. Hershmann, S. Chen, T. Niblack, T. Anderson, T. Welacky, C. Grau, and A. MacGuidwin. 2000. Effects of tillage and row spacing on soybean yield and soybean cyst nematode reproduction. Journal of Nematology 32:427.
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Progress 10/01/99 to 09/30/00
Outputs
The North Central regional nematology group (NC-215) distributed two aliquot soil samples each to a representative from each participating state during its July 2000 meeting in South Dakota. The plan was for nematologists in each state to process the two samples (all the original samples were taken from a single large soil sample) and to obtain the number of eggs of soybean cyst nematode (SCN) plus J2 second stage juveniles (the stage that hatches from the egg) and report back. Great variation occurred in the counts. For replicate 1, the low count was 20,400 and the high count was 119,000. For replicate 2, the low count was 14,600 and the high count was 120,320. The overall mean count for all samples processed by nematologists from the 8 states was 53,561. Our (Indiana) counts were closest to the overall mean for both replicates and all states: replicate one, Indiana count = 56,400, and replicate two, Indiana count = 55, 440, overall Indiana mean count = 55,920. The
low counts varied among states, but the Missouri counts were considerable higher than all the rest. It is not clear why such great disparities occurred in the counts from the different laboratories. The NC-215 project proposal was revised to reflect the goals of the group for the next 5 years (10/01/99 - 8/31/04). A summary of the collective results from previous work to determine over winter survival of SCN indicated that unlike the southern states where SCN populations decline 25-40% during the winter, SCN populations in the North Central region appear to be well adapted to the cold and freezing conditions and survivorship often approaches 100%. Rotation with non-host crops usually causes reduction in soil populations. A problem is that often weed species in fields harbor SCN and may prevent the kinds of soil reductions in inoculum that otherwise might be expected. The new project will emphasize testing of control tactics and programs designed to accelerate the attrition of SCN
populations in soils.
Impacts
Soybean cyst nematode (SCN) is the most important pest of soybeans in the U.S. and is of great economic importance in the North Central region, where soybeans are a major crop. Many soil, weather and management factors affect the soil populations of SCN that comprise the inoculum for susceptible soybean cultivars. A better understanding of the factors that accelerate the attrition of SCN in the soil can lead to better management of the pest. Cooperative research, which helps to better understand regionally variable phenomena acting on soil populations of SCN, can maximize the productivity of the small group of nematologists present in the eight cooperating states.
Publications
- Donald, P.A., G. R. Noel, H. Melakerberhan, N. Atibalentja, T. R. Anderson, S. Y. Chen, J. Faghihi, J. M. Ferris, C. R. Grau, D. E. Hershman, A. E. MacGuidwin, T. L. Niblack, R. D. Riggs, W. C. Stienstra, G. L. Tylka and T. Welacky. 1999. Ten-state evaluation of selected agronomic practices on soybean cyst nematode. Journal of Nematology, 31: 531.
- Faghihi, J., R. A. Vierling, V. R. Ferris and J. M. Ferris. 1999. Performance of germplasm PUSCN14 with Hartwig resistance in a field highly infested with soybean cyst nematode. Journal of Nematology, 31: 534.
- Workneh, F, G. L. Tylka, X. B. Yank, J. Faghihi, and J. M. Ferris. 1999. Regional assessment of soybean brown stem rot, Phytophthora sojae, and Heterodera glycines using area-frame sampling: Prevalence and effects of tillage. Phytopathology, 89: 204-211.
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Progress 10/01/98 to 09/30/99
Outputs
In ongoing experiments designed to determine the overwintering survival rate of soybean cyst nematode, and factors affecting overwinter survival, we again collected post harvest soil samples in the fall of 1998. In spring 1999, prior to planting, soil samples were again collected from the same fields/locations where the previous samples had been collected. After thorough mixing of soil in each bag, a 250 cc volume, based on displacement in water, was processed to recover cysts. Cyst walls were mechanically ruptured to release eggs, and aliquots counted to determine number of eggs. Eggs were further categorized as healthy or diseased, based on color and general appearance. At one location numbers of eggs recovered increased 103% between fall and spring; at the other location the increase was 345%. Eggs judged to be diseased were 2.7% in the fall at both locations, and 8.6-11.4% in the spring. Data from this and previous years are not sufficiently strong to conclude
that diseased eggs are a dominant mechanism influencing winter survival. To examine the effect of temperature on survival and viability of eggs (the presumed overwintering stage of the nematode), a pathogenicity test was conducted. Soybeans were grown in glass tubes containing a known volume of soil and maintained at an optimum growing temperature. The number of cysts which developed in each tube was counted. Numbers of females developing in soil immediately after the fall collection ranged from 34 to 38. After 4 months of different storage regimes [1) outside, 2) lab, 3) greenhouse or 4) freezer] soil was again placed in tubes, soybean seed planted and the numbers of developing females enumerated. The numbers developing in soil stored outside ranged from 104 to 138; and the numbers for lab, greenhouse and freezer ranged from 22-30, 26-30, 68-116, respectively. From these data we concluded that cold storage is better than warm storage for survival of this nematode.
Impacts
Soybean cyst nematode (SCN) is the most serious pest of soybeans. Once found in a field, it cannot be eradicated; therefore one must manage the pest so that yields are not adversely affected. Information about survival of this organism across the principal soybean growing regions of the U. S. is fragmentary and needs to be investigated further to facilitate good management strategies.
Publications
- Faghihi, J., Vierling, R.A., Ferris, V.R. and Ferris, J.M. 1998. Yield data for soybean lines with Hartwig resistance to soybean cyst nematode. Journal of Nematology 30:495.
- Ferris, V.R., Riggs, R.D., Sabo, A., Faghihi, J. and Ferris, J.M. 1998. Relationships of Cactodera betulae to other cyst nematodes based on ribosomal DNA. Phytopathology 88:S28.
- Ferris, V.R., Subbotin, S.A., Ireholm, A., Spiegel, Y., Faghihi, J. and Ferris, J.M. 1998. Ribosomal DNA sequence analysis and comparisons of H. filipjevi and H. latipons isolates from Russia. Nematologica 44:493.
- Ferris, J.M. and Ferris, V.R. 1998. Biology of plant-parasitic nematodes. Pp. 21-35 in Plant and Nematode Interactions, eds, Barker, K.R., Pederson, G.A. and Windham, G.L. American Society of Agronomy, Madison, WI.
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Progress 10/01/97 to 09/30/98
Outputs
Early results in this continuing study of overwinter survival of Heterodera glycines suggested that numbers of eggs in soil increased during the interval between fall and the following spring. Subsequent research did not provide any explanation for these observations, and occasionally there was a decrease of eggs over the winter period. Goals for the past year were to identify factors that might affect overwinter survival, and whether a pattern could be found over a longer period of sampling. Post harvest soil samples were collected at two Indiana locations on 16 December 1997: Purdue Agronomy Farm (fourth-year soybeans, no tillage) and a Tippecanoe County field (Slayton farm, first-year corn following soybeans, minimum tillage). Replicate soil samples were again collected from each of these same sites on 17 April 1998. All soil cores were taken to a depth of 30 cm. After mixing, a 250 cc volume of soil, based on displacement of water, was processed to recover cysts.
Cyst walls were mechanically ruptured to release eggs. Eggs were counted and categorized as healthy or diseased, based on color and general appearance. There was an 18% increase in numbers of eggs at the Agronomy Farm and a 44% decrease in numbers at the Tippecanoe County location. Percentages of diseased eggs decreased between Fall and Spring at the two locations, although the percentage of diseased eggs appeared to be much less in the Spring 1998 sample from Tippecanoe County than at the Fall 1997 sampling time. These data obtained were not sufficiently strong to conclude that diseased eggs are a dominant mechanism influencing winter survival. To examine other possible factors influencing survival, a preliminary test was carried out to explore the effects of temperature on viability of SCN eggs within cysts collected in the fall. Roots of soybeans planted in soil stored in the laboratory or on a greenhouse bench yielded the same numbers of females as from roots of soybeans planted
immediately after sampling. Increased numbers of females were found on roots of plants grown in soil stored in the freezer over winter.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 10/01/96 to 09/30/97
Outputs
An ongoing study to determine the overwinter survival of soybean cyst nematode (SCN) in the North Central region was continued. In November and December 1996, replicate post-harvest soil samples were collected at two Indiana locations: the Purdue Agronomy Farm (third-year soybeans, no-tillage), and a Tippecanoe County field (Slayton farm, first-year soybeans, minimum tillage). Replicate soil samples were again collected from each field in March 1997. All soil cores were taken to a depth of 30 cm. Equal aliquot volumes of soil were processed from each sample, cysts recovered, and cyst walls dissolved to release eggs. The numbers of eggs were determined and the eggs were examined and categorized as healthy or diseased. Data showed a 21% increase in numbers of eggs at the Agronomy Farm and a 10% decrease in numbers at the Tippecanoe County location. Percentages (8 - 15%) of diseased eggs were comparable at the two locations on both sampling dates, although the Fall 1996
sample from the Tippecanoe Co. location had lowest percentage of diseased eggs (8%). Although our initial hypothesis had been that the percentages of diseased eggs would provide an explanation for differences we had observed in winter survival of SCN in earlier years, the 1996-97 data did not support this explanation. In future experiments, we plan to enlarge the study to include a study also of the effect of storage temperatures, constant and variable, on overwinter survival. Similar experiments are being carried out at other locations in the North Central region, so that data from all experiments can be compared.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 10/01/95 to 09/30/96
Outputs
In 1995-96, additional data were collected to determine overwinter survival of soybean cyst nematode (SCN), Heterodera glycines. In an attempt to test an explanation for the dramatic increases in egg numbers between fall '94 and spring '95, upper and lower soil cores collected in fall '95 and spring '96 were processed separately. This change in sample processing was designed to explore the possibility that movement of nematodes upward through the soil profile was responsible for the observed population increase during the 94/95 winter. In egg counts from 95/96 samples from two locations, both with no-tillage continuous soybeans, far more nematodes were found in the top half soil cores than bottom half cores. Numbers declined in both top and bottom sections of the cores over the winter, but the percentage decline was higher for the bottom half. Percent of diseased eggs was slightly higher for the bottom cores than the upper ones. These data suggest that egg migration
(via soil water percolation) cannot account for results obtained previously.
Impacts
(N/A)
Publications
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Progress 10/01/94 to 09/30/95
Outputs
Data from soybean cyst nematode (SCN), Heterodera glycines, egg counts from post-growing-season (1994) soil samples compared with counts from soil samples collected from the same sites prior to spring (1995) cultivation indicated increases of 180-300% over the winter period at three different field sites. Other technical committee researchers observed similar trends for over-winter survival. This study of winter survival of SCN is continuing during the 1995-96 winter period. In order to seek an explanation for the apparent population increase, aliquots from the post-harvest samples will be processed at two time periods: immediately following collection, and again at the time the spring samples are collected.
Impacts
(N/A)
Publications
- NO PUBLICATIONS REPORTED THIS PERIOD.
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Progress 10/01/93 to 09/30/94
Outputs
Post-growing-season soil samples have been collected from selected soybean fields infested with soybean cyst nematode (SCN), Heterodera glycines. These samples will be processed to determine egg populations. Prior to spring cultivation, post-winter soil samples will be collected and also processed to recover SCN eggs. Associated physical, chemical and biological attributes of soil will be associated with these data in an attempt to determine overwinter survival rates and factors affecting overwinter survival of SCN.
Impacts
(N/A)
Publications
- No publications reported this period.
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