Crop Science 41:1137-1143 (2001)
© 2001 Crop Science Society of America
CROP ECOLOGY, MANAGEMENT & QUALITY
Effect of Crop Rotation and Cultivar Resistance on Seed Yield and the Soybean Cyst Nematode in Full-Season and Double-Cropped Soybean
J. H. Long, Jr.*,a and
T. C. Toddb
a Kansas State Univ., Southeast Agricultural Research Center, P.O. Box 316, Parsons, KS 67357
b Dep. of Plant Pathology, Throckmorton Hall, Kansas State Univ., Manhattan, KS 66506
* Corresponding author (jlong{at}oznet.ksu.edu)
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ABSTRACT
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Soybean cyst nematode (Heterodera glycines Ichinohe) can cause considerable damage to soybean [Glycine max (L.) Merr.], especially in western USA growing areas that are newly infested. The objective of this study was to find cultural practices that reduce cyst nematode effect on soybean in this region. Four management systems, one having continuous susceptible soybean, a second consisting of a 3-yr rotation with 2 yr of a nonhost crop followed by susceptible soybean, and two 4-yr rotations alternating a susceptible and resistant cultivar with non-host crops, were investigated at nematode-infested and noninfested locations. One 4-yr rotation had full-season soybean while the other had double-crop soybean. Data included soybean seed yield, yield components, and cyst nematode egg density. Grain yields of full-season, SCN-susceptible ‘Stafford’ were similar in all rotations at each location. Nonhost crops reduced nematode densities from 4000 eggs 100 cm-3 in continuously cropped SCN-susceptible plots to 1000 and 500 eggs 100 cm-3 in 3- and 4-yr rotations, respectively. However, nematode numbers rapidly increased to more than 5000 eggs 100 cm-3 by seasons end when susceptible soybean was grown. The SCN-susceptible cultivar produced 33% less grain and pods than did the SCN-resistant cultivar, Manokin, at the infested location while the cultivars yielded similarly at the noninfested site. Full-season and double-cropped soybean reacted similarly to SCN. Crop rotation reduced cyst nematode numbers, but this benefit did not reduce yield losses on subsequent SCN-susceptible soybean as numbers rapidly climbed to damaging levels.
Abbreviations: Pi, Pf, number of encysted eggs and juveniles per 100 cm3 soil at planting and harvest, respectively
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INTRODUCTION
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SOYBEAN CYST NEMATODE has long been recognized as a serious pest of soybeans in the northcentral and southeastern regions of the USA. However, cyst nematode infestations have been discovered only recently in many western U.S. soybean areas. Edaphic and climatic conditions in these areas, such as shallow soils, sandy soils with low damage thresholds, and periodic summer droughts may combine to make management of the nematode in this region very difficult with traditional control methods developed in other regions.
Work on the soybean cyst nematode in other regions of the USA has focused on predicting yield loss on the basis of preplant cyst populations (Duncan, 1991), management of the pest through crop rotation (Francl and Dropkin, 1986; Koenning et al., 1993, 1995; Ross 1962; Sasser and Uzzell, 1991; Schmitt, 1991; Young and Hartwig, 1988), and the use of resistant cultivars (Hartwig et al., 1987; Wallace et al., 1995). The programs that were developed continuously suppress nematode numbers below damaging levels, while minimizing the chances of nematode race shifts over many years.
A rotation of resistant and susceptible soybean cultivars with a nonhost crop is a common management recommendation for soybean cyst nematode throughout the southeastern and midwestern USA (Schmitt, 1991; Jardine and Todd, 1995; Young, 1988). Susceptible soybean are grown in the rotation when cyst nematode populations in the soil are low. This theoretically reduces selection pressure for races which can infect resistant cultivars, although the value of this practice has been questioned (Hartwig et al., 1987; Young and Hartwig, 1988). Yield of susceptible soybean, followed by a nonhost crop, corn (Zea mays L.), was greater than the yield of continuous soybeans (Koenning et al., 1993, 1995; Ross, 1962; Howard et al., 1998). However, conflicting reports have shown little (Sasser and Uzzell, 1991; Schmitt, 1991) or no effect (Francl and Dropkin, 1986) of a single nonhost crop such as cotton (Gossypium hirsutum L.) or corn on a subsequent susceptible soybean crop. When nonhost crops have been grown for 2 or 3 yr cyst nematode numbers decreased below levels that were damaging to a susceptible soybean (Francl and Dropkin, 1986; Koenning et al., 1993, 1995; Ross, 1962; Sasser and Uzzell, 1991; Schmitt, 1991).
Time of planting has shown mixed results in its ability to help reduce cyst nematode damage. Koenning and Anand (1991) found that delayed planting in Missouri resulted in fewer nematodes present at planting but greater nematode densities at soybean maturity. Todd (1993) found that delayed planting in Kansas had variable effects on nematode densities and soybean seed yields. Hussey and Boerma (1983) and Schmitt (1991) found that in the southern USA late planting does not reduce cyst reproduction or grain yield loss while Koenning et al. (1993) found that late planting had variable results in reducing cyst numbers. Studies in which soybeans were planted immediately after winter wheat (Triticum aestivum L.) harvest (double cropping) have shown decreases in cyst production and yield loss (Baird and Bernard, 1984; Hershman and Bachi, 1995). Although some of this effect might have been related to planting date, most was attributed to a wheat stubble effect that was more pronounced as tillage was reduced (Hershman and Bachi, 1995).
Genetic resistance incorporated into adapted soybean cultivars is an important component in cyst nematode management. In soybean cyst nematode-infested soils in southeastern Kansas, susceptible cultivars typically produce 30 to 40% lower seed yields than do resistant cultivars (Winkler et al., 1993; Todd et al., 1995). This difference varies with cultivar maturity, with maturity group V cultivars exhibiting less yield loss than maturity group III and IV cultivars (Todd, 1993). The magnitude of yield loss also varies with soil type, with sandy or shallow, clay-pan soils, associated with much lower damage thresholds (Todd, unpublished data).
Results from studies in the southeastern USA suggest that rotations of nonhost crops with both resistant and susceptible soybean cultivars provide the best soybean cyst nematode management strategy. Although some disagreement exists as to the effect of the use of a nonhost crop for only 1 yr, most agree that a crop rotation of nonhosts and resistant cultivars eventually decreases the cyst nematode densities to levels that allow the periodic use of a susceptible soybean. Because of the recent introduction of soybean cyst nematode, the effects of various management strategies are not as well documented for the western regions of the U.S. soybean growing area. The objective of this study was to determine the effects of crop rotation with both nonhosts and resistant soybean in combination with a susceptible cultivar, on full-season and double-cropped soybean seed yields and cyst nematode populations. In addition, all treatments at the cyst infested location were repeated at an uninfested location for comparison.
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MATERIALS AND METHODS
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This study was at two locations near Columbus, Cherokee County, Kansas, with a geographic position of latitude of 37°12'N and longitude 94°52'W. Fields were in soybean production, some continuously, for many years. The two locations were approximately 5.5 km apart both on a Parsons silt loam (fine, mixed thermic Mollic Albaqualf). One location, Martin Farms, was heavily infested with the soybean cyst nematode. The second location, at the Southeast Agricultural Research Center (Columbus Field), had no detectable levels of the nematode.
Average rainfall is adequate with over 1000 mm of precipitation. However, rainfall in the two hottest months, July and August when soybean is flowering and setting pods, is unpredictable and only 67 to 75% as much as in either June or September (Table 1). The lack of rainfall during this two-month period greatly affects soybean potential yield by reducing the number of flowers and small pods retained by the plants and compounds the nematode effect of pruning soybean roots.
A 1.2-ha field at Martin Farms and 0.75-ha field at the Columbus Field were grid sampled on 5-m2 dimensions in 1991 to determine trends of cyst nematode infestation. The Martin Farms ranged from 400 to 3000 eggs and juveniles in 100 cm3 soil while the Columbus Field had no detectable levels of the nematode. Replications at the Martin Farm were laid out in areas of similar nematode infestation with treatments allotted within each replication. Each replication at both locations contained all phases of each rotation, so that not only rotations but the use of resistant and susceptible cultivars within each rotation could be compared each year. Each plot within a replication was 3.1 m wide by 9.2 m long and trimmed to 7.6 m for harvest.
Crop rotations were begun in late 1991 when wheat was planted, and comparisons were made from 1995 until 1998. At that time, the 4-yr rotation, which allowed susceptible soybean to be grown following 3 yr of a nonhost and resistant cultivar, could be compared to all other soybean crops. Four crop rotations were used: continuous susceptible soybean (S-S-S), a 3-yr rotation with 2 yr of a nonhost crop followed by susceptible soybean (N-N-S): and two 4-yr rotations with a nonhost crop followed by resistant soybean, then a nonhost crop followed by a susceptible cultivar (N-R-N-S). The 3-yr rotation consisted of grain sorghum (Sorghum bicolor [L.] Moench), followed by wheat (planted in fall after sorghum harvest)/summer fallow, followed by SCN-susceptible soybean. One of the 4-yr rotations was grain sorghum, an SCN-resistant soybean cultivar, grain sorghum again, then the SCN-susceptible soybean cultivar. The other 4-yr rotation was similar, but included winter wheat after the grain sorghum so that soybean grown every other year were double cropped.
During the period 1995 to 1998, the SCN-susceptible soybean cultivar was Stafford and the SCN-resistant cultivar was Manokin. Both cultivars were early group V maturity. Manokin has the ‘Peking’ source of resistance to races 1 and 3 of the cyst nematode, which were predominant in the area (Schapaugh et al., 1994). The grain sorghum hybrid was Pioneer 8500, and the winter wheat cultivar was Karl 92. Planting rates for soybean, grain sorghum, and wheat were 260 000, 170 000, and 1200 thousand seed ha-1, respectively. Soybean and grain sorghum were planted in rows 0.75 m apart, while wheat was planted in rows 0.2 m apart. Planting dates at both locations for full season soybean and grain sorghum were 22 June 1995, 7 June 1996, 9 June 1997, and 19 May 1998. Planting dates at both locations for double crop soybean were 5 July 1995, 11 July 1996, 3 July 1997, and 18 June 1998. Harvest dates for all spring planted crops at both locations were 12 Oct. 1995, 14 Oct. 1996, 23 Oct. 1997, and 14 Oct. 1998. Wheat was planted at both locations on 2 Dec. 1994, 20 Oct. 1995, 17 Oct. 1996, and 24 Oct. 1997. It was harvested at both locations on 15 June 1995, 26 June 1996, 2 July 1997, and 18 June 1998. Fertilizer on all crops each year was 13 kg ha-1 N, 54 kg ha-1 P, and 54 kg ha-1 K applied before planting. In addition on wheat and grain sorghum each year 103 kg ha-1 of N was provided as urea before planting. Weed control was achieved on spring-planted crops each year at both locations with an application of 1.67 kg ha-1 of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] immediately after planting followed by a postemergent application of 1.67 kg ha-1 bentazon [3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide].
To determine soybean seed yield at both locations, the two middle of four rows in each plot were harvested with an MF 8 combine equipped with weigh scales and a moisture meter. Seed yield was reported on a 130 g kg-1 corrected moisture basis for soybean and wheat and 125 g kg-1 for grain sorghum. Soybean yield components were determined by hand harvesting 0.6 m of two harvest rows of each plot to equal 1.2 m length.
Soil samples taken at both locations consisted of a composite sample of four 5-cm-diam soil cores collected to a depth of 15 cm from the middle two rows of each plot. Samples were collected every 3 yr at harvest from the continuous soybeans at Columbus and yearly at planting and harvest at Martin Farms for cyst extraction. Cysts were collected from 100-cm3 subsamples on a 150-µm-pore sieve and mechanically ruptured to release eggs and second-stage juveniles (Niblack et al., 1993). Eggs and juveniles were counted at x40 magnification.
All data were subjected to analysis of variance by the General Linear Models procedure in SAS (SAS Institute, Cary, NC). Contrasts were developed to evaluate the effects of crop rotation on the SCN-susceptible cultivar (rotation within cultivar and double-cropping), of cultivars across the full-season and double-cropped 4-yr rotations (cultivar within rotation), of double-cropping across cultivars in the 4-yr rotations (double-cropping within rotation), and the interaction of cultivar and double cropping (cultivar x double-cropping within rotation). Cropping system means were separated according to least squares means (LSMEANS procedure in SAS). Mean separations were then computed. Nematode data were transformed to log10 (x + 1) values before analysis to reduce heterogeneity of variances.
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RESULTS AND DISCUSSION
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Crop Rotation
Crop rotation had little influence on grain yield of the SCN-susceptible cultivar at Martin Farms (Table 2). Continuously-cropped SCN-susceptible soybean yields were similar to those from the 3- and 4-yr rotations in all years of the study. These results contrast with those of Howard et al. (1998), where alternating soybean with corn produced higher soybean yields vs. continuous cropping in five of six years, but are consistent with prior observations of substantial soybean cyst nematode-induced yield loss with initial low egg densities in the shallow silt loam soils in Kansas (Todd et al., 1995)
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Table 2. Within-years analyses of variance for soybean yield and cropping system means for grain yield at the SCN-infested Martin Farms site.
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Crop rotation was effective in reducing cyst nematode numbers before the SCN-susceptible soybean were planted. Number of eggs and juveniles extracted from cysts at planting were reduced (P 
0.05) 75% following 2 yr of nonhost crops and 87% following 3 yr of grain sorghum and resistant soybean (Table 3). No reduction was detected following a single year of grain sorghum. This latter observation is in contrast to reports by Koenning et al. (1993)( 1995), where 1 yr of nonhost crops resulted in low soybean cyst nematode egg densities. However, the rate of population decline is known to be much lower in the northcentral compared to the southeastern USA, where most rotation work has been done (NC-215 committee, personal comm.). Nematode counts following an SCN-susceptible soybean in the 3- and 4-yr rotations were similar to that of continuously-planted SCN-susceptible soybean (Table 3). This uniformity in Pf was an expected result of density-dependent population increase by the nematode (Francl and Dropkin, 1986), which is clearly depicted by the Pf/Pi values in Table 3. For example, plots with full-season continuous Stafford had stable, but high, populations of the cyst nematode and only marginal population increases. In contrast, explosive 6- and 12-fold increases in populations were seen when SCN-susceptible soybean was grown following 2- and 3-yr, respectively, of nonhost and resistant soybean crops. These high rates of population increase suggest a possible mechanism for the reduced soybean yields observed when the SCN-susceptible soybean was grown in relatively long-term 3- and 4-yr rotations. Koenning et al. (1993), however, reported positive yield responses in the presence of similarly large population increases of soybean cyst nematode on soybean following nonhosts compared to soybean monoculture. Climatic conditions, such as typically hot and dry weather during July and August and shallow clay-pan soils contributed greatly to the considerable yield loss due to this population increase.
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Table 3. Across-years analyses of variance and cropping system means for Heterodera glycines egg densities and population increase on soybean at the Martin Farms site.
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Grain yields of continuous SCN-susceptible soybean at Columbus also were similar across rotations in most years (Table 4). However, in isolated cases during 1995 and in 1996, crop rotation increased yields by 15% over continuous soybeans. The basis for this rotation effect in the absence of soybean cyst nematode can not be directly determined from the data collected, but charcoal rot, caused by the fungus Macrophomina phaseolina, was present each year. This plant disease has been shown to be a contributing factor to yield reduction in soybean (Pearson et al., 1984), with crop rotation reducing soil populations of the fungus (Pearson et al., 1987).
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Table 4. Within-years analyses of variance for soybean yield and cropping system means for grain yield at the noninfested Columbus site.
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Cultivar Resistance
Seed yields of the SCN-resistant cultivar were higher than those of the SCN-susceptible cultivar across cropping systems at Martin Farms (Table 2). Yield increases resulting from planting a resistant cultivar were similar for full-season and double-cropped soybean in rotation with grain sorghum, averaging 31 and 35%, respectively. Within each cropping system, the resistant cultivar had higher seed yield (P 0.05) than the susceptible soybean in three of four years. The cultivar effect seen in this study was less than seen in previous studies with continuous soybeans at this location (Todd et al., 1995). The difference between cultivars at Martin Farms varied between full-season and double-cropped systems, with the SCN-resistant cultivar producing 49 and 27%, respectively more pods than the SCN-susceptible cultivar (Table 5). These results agree with previous research suggesting that pod abortion accounts for most of the soybean cyst nematode-induced seed yield losses on susceptible soybean cultivars (Todd et al., 1995). In contrast, number of seeds pod-1 were comparably lower (P 0.05) for the SCN-resistant vs. SCN-susceptible cultivar at Martin Farms (Table 5).
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Table 5. Across-years analyses of variance for soybean yield components and cropping system means for yield components at the SCN-infested Martin Farms site.
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Cultivar effects on cyst nematode population densities were consistent and predictable, with lower (P 0.05) populations following the SCN-resistant cultivar compared to the SCN-susceptible cultivar (Table 3). Resistant soybean cultivars generally maintain low population densities of the nematode, while susceptible cultivars allow rapid population recovery (Todd et al., 1995; Howard et al., 1998). Cultivar differences were most notable at the end of each growing season (i.e., Pf and Pf/Pi), but remained detectable after a succeeding nonhost crop, as indicated by reduced Pi in the 4-yr rotations where the SCN-resistant cultivar was the preceding soybean crop. Large pre-plant population densities of soybean cyst nematode in plots where the SCN-resistant cultivar was planted are important for two reasons. First, high numbers of the nematode were still present after only 1 yr of rotation to a nonhost crop and, second, the resistant cultivar was under heavy cyst-nematode pressure when grown as a full-season crop yet it still performed very well. Substantial declines in nematode population densities following a single crop of the SCN-resistant cultivar resulted in a Pf that was more than 95% lower than that on the SCN-susceptible cultivar in both full-season and double-cropped plots. While it may seem best to continuously use resistant cultivars other studies have shown it results in increased cyst nematode reproduction relative to susceptible cultivars (Young et al., 1986; Young and Hartwig, 1992). Crop rotation with nonhost crops in these studies slowed the occurrence of race shifts.
A cultivar effect (P 0.05) was observed at Columbus in two of the four years, only in double-cropped soybeans (Table 4). The SCN-resistant cultivar Manokin performed better than the SCN-susceptible Stafford as a double-cropped cultivar and is popular in the region because of this characteristic. SCN-resistant soybean yields were 20 and 45% greater than the SCN-susceptible soybean yields in double-cropped rotations in 1995 and 1998, respectively. Consideration of this difference in performance between the two cultivars suggests that the SCN-susceptible cultivar exhibited less yield loss due to soybean cyst nematode (see Table 2) when double-cropped than when grown as a full-season crop. The SCN-resistant cultivar produced more pods per meter of row compared to the SCN-susceptible cultivar at both locations (P 0.05) although this effect was most pronounced at the Martin Farms site (Tables 5 and 6). At the noninfested Columbus location, the SCN-resistant cultivar averaged 19% more pods per meter of row than the SCN-susceptible cultivar (Table 6). Again, the number of seeds pod-1 were comparably lower (P 0.05) for the SCN-resistant vs. SCN-susceptible cultivar.
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Table 6. Across-years analyses of variance for soybean yield components and cropping system means for yield components at the noninfested Columbus site.
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Double-Cropping
Little benefit was attributable to double-cropping as a management tool to reduce cyst nematode damage. Yield losses (measured as the yield difference between the SCN-resistant and susceptible cultivar within a cropping system) at the Martin Farms location were similar between double-cropped and full-season soybeans (Table 2). Grain yields were much lower, however, for double-cropped vs. full-season soybeans (both resistant and susceptible) in two of the four years. Double-cropped soybean yields at Martin Farms were reduced in 1996 and 1997 compared to full-season soybean yields (Tables 2). Double-cropped soybeans at the Martin Farms location averaged 29 and 16% fewer (P 0.05) pods per meter of row than full-season soybeans for both the SCN-resistant and susceptible cultivars, respectively (Table 5). Unlike seed yields, the effects of double-cropping on numbers of pods was consistent across years.
Double-cropping of soybean had no measurable effect on soybean cyst nematode Pf but tended to reduce the rate of population increase on the SCN-susceptible cultivar (double crop and cultivar x double-cropping contrasts were not significant; Table 3). In contrast, a lower (P 0.05) soybean cyst nematode Pi was observed for the double-cropped 4-yr rotation compared to the full-season 4-yr rotation when the previous soybean crop was SCN-susceptible. A previous study at this location (Todd, 1993) found that delayed planting did not reduce soybean cyst nematode population densities, while other studies have reported reduced numbers associated with wheat/soybean double-cropping, although there is little consensus about mechanisms such as wheat stubble vs. delayed planting (Koenning and Anand, 1991; Hershman and Bachi, 1995).
Grain yields of doublecropped soybean at the Columbus station were also greatly reduced in 1996 and 1997 (Table 4). Numbers of pods per meter of row in double-cropped soybeans were 18% lower (P 0.05) than full-season soybeans across cultivars (Table 6). Again, the effects of double-cropping on numbers of pods was consistent across years.
Double cropping of soybean offers little promise in reducing cyst nematode damage because any reduction in cyst nematode numbers does not offset the reduced yield potential associated with double-cropping some years or result in a relative increase in yield.
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CONCLUSIONS
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Crop rotation was effective in reducing preplant population densities of soybean cyst nematode but explosive reproduction of the nematode resulted in serious damage to the SCN-susceptible cultivar during the first year back into soybean production. Results differ from studies that have shown 3- and 4-yr rotations to benefit SCN-susceptible cultivars but were influenced by summer drought typical in this region of the USA. Yields of SCN-resistant soybean were consistently much greater than those of the SCN-susceptible cultivar across all cropping systems when the cyst nematode was present, but not when the nematode was absent. Such reliance on host resistance increases concerns about selection pressure on soybean cyst nematode populations, however strategies for addressing this problem are currently being investigated. Double cropping of soybean did not help in cyst management as yield loss in the SCN-susceptible cultivar was comparable to that seen in full-season soybean.
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ACKNOWLEDGMENTS
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The authors wish to acknowledge and thank the Kansas Soybean Commission for financial support provided through soybean check off funds, Neil and Gary Martin of Martin Farms, and former and current Cherokee County Kansas extension agents Ted Wary and Dennis Elbrader. Also thanks to technicians, Charlie Middleton, Joyce Erikson, and Kelly Kusel.
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NOTES
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Kansas Agric. Exp. Stn. Contribution no. 00-364-J.
Received for publication June 27, 2000.
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REFERENCES
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|---|
- Anand, S.C., and S.R. Koenning. 1986. Tolerance of soybean to Heterodera glycines. J. Nematol. 18:195–199.
- Baird, S.M., and E.C. Bernard. 1984. Nematode population and community dynamics in soybean-wheat cropping and tillage regimes. J. Nematol. 16:379–386.
- Duncan, L.W. 1991. Current options for nematode management. Annu. Rev. Phytopathol. 29:469–490.
- Francl, L.J., and V.H. Dropkin. 1986. Heterodera glycines population dynamics and relation of initial population to soybean yield. Plant Dis. 70:791–795.
- Hartwig, E.E., L.D. Young, and N. Buehring. 1987. Effects of monocropping resistant and susceptible soybean cultivars on cyst nematode infested soil. Crop Sci. 27:576–579.[Abstract/Free Full Text]
- Hershman, D.E., and P.R. Bachi. 1995. Effect of wheat residue and tillage on Heterodera glycines and yield of doublecrop soybean in Kentucky. Plant Dis. 79:631–633.
- Howard, D.D., A.Y. Chambers, and G. Lessman. 1998. Rotation and fertilization effects on corn and soybean yields and soybean cyst nematode population in a no-tillage system. Agron. J. 90:518–522.[Abstract/Free Full Text]
- Hussey, R.S., and H.R. Boerma. 1983. Influence of planting date on damage to soybean caused by Heterodera glycines. J. Nematol. 15:253–358.
- Jardine, D.J., and T.C. Todd. 1995. Soybean Cyst Nematode. KS St. Univ. Coop. Ext. Serv. Pub. L-787 Revised. September 1995.
- Koenning, S.R., and S.C. Anand. 1991. Effects of wheat and soybean planting date on Heterodera glycines population dynamics and soybean yield with conventional tillage. Plant Dis. 75:301–303.
- Koenning, S.R., D.P. Schmitt, and K.R. Barker. 1993. Effects of cropping systems on population density of Heterodera glycines and soybean. Plant Dis. 77:780–787.
- Koenning, S.R., D.P. Schmitt, K.R. Barker, and M.L. Gumpertz. 1995. Impact of crop rotation and tillage system on Heterodera glycines population density and soybean yield. Plant Dis. 79:282–286.
- Niblack, T.L., R.D. Heinz, G.S. Smith, and P.A. Donald. 1993. Distribution, density, and diversity of Heterodera glycines in Missouri. Suppl. J. Nematol. 25:880–886.
- Pearson, C.A.S., J.F. Leslie, and F.W. Schwenk. 1987. Host preference correlated with chlorate resistance in Macrophomina phaseolina. Plant Dis. 71:828–831.
- Pearson, C.A.S., F.W. Schwenk, F.J. Crowe, and K. Kelley. 1984. Colonization of soybean roots by Macrophomina phaseolina. Plant Dis. 68:1086–1088.
- Ross, J.P. 1962. Crop rotation effects on the soybean cyst nematode population and soybean yields. Phytopathology 52:815–818.
- Sasser, J.N., and G. Uzzell, Jr. 1991. Control of the soybean cyst nematode by crop rotation in combination with a nematicide. J. Nematol. 23:333–337.
- Schmitt, D.P. 1991. Management of Heterodera glycines by cropping and cultural practices. J. Nematol. 23(3):338–352.
- Schapaugh, W.T., Jr., K.L. Roozeboom, T. Todd, P. Evans, J. Long, M. Witt, M. Claassen, B. Gordon, K. Jansen, L. Maddux, B. Marsh, and V. Martin. 1995. 1994 Kansas Performance Tests with Soybean Varieties, KAES Report of Progress 723.
- Todd, T.C. 1993. Soybean planting date and maturity effects on Heterodera glycines and Macrophomina phaseolina in southeastern Kansas. Suppl. J Nematol. 25:731–737.
- Todd, T.C., W.T. Schapaugh, Jr., J.H. Long, and B. Holmes. 1995. Field response of soybean in maturity groups III-V to Heterodera glycines in Kansas. Suppl. J. Nematol. 27:628–633.
- Wallace, M.K., J.H. Orf, and W.C. Stienstra. 1995. Field population dynamics of soybean cyst nematode on resistant and susceptible soybeans and their blends. Crop Sci. 35:703–707.
- Winkler, H.E., B.A.D. Hetrick, and T.C. Todd. 1993. Interactions of Heterodera glycines, Macrophomina phaseolina, and mycorrhizal fungi on soybean in Kansas. Suppl. J. Nematol. 26:675–682.
- Young, L.D. 1998. Influence of soybean cropping sequences on seed yield female index of the soybean cyst nematode. Plant Dis. 82:615–619.
- Young, L.D., and E.E. Hartwig. 1992. Cropping sequence effects on soybean and Heterodera glycines. Plant Dis. 76:78–81.
- Young, L.D., and E.E. Hartwig. 1988. Selection pressure on soybean cyst nematode from soybean cropping sequences. Crop Sci. 28: 835–837.[Abstract/Free Full Text]
- Young, L.D., E.E. Hartwig, S.C. Anand, and D. Widick. 1986. Responses of soybeans and soybeans cyst nematodes to cropping sequences. Plant Dis. 70:787–791.
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ABSTRACT
INTRODUCTION
