IMPACT OF RAPHANUS AND BRASSICA CULTIVARS ON  

HETERODERA GLYCINES (Nematoda) POPULATION DEVELOPMENT 

 
By 

Jeffrey J. Shoemaker 

 

 

 

 

A THESIS 

Submitted to 

 Michigan State University  

in partial fulfillment of the requirements  

for the degree of  

 

Entomology – Masters of Science 

2018 

 

 

ABSTRACT 

IMPACT OF RAPHANUS AND BRASSICA CULTIVARS ON  

HETERODERA GLYCINES (Nematoda) POPULATION DEVELOPMENT 

By 

Jeffrey J. Shoemaker 

Heterodera glycines, Soybean Cyst Nematode (SCN), is a devastating pathogen to Soybeans 

(Glycines max).  The objectives of this M.S. Thesis were to: 1) Identify cover crops that are non-

hosts for SCN other than the Gramminaceae, with special references to radishes and mustards, 

under greenhouse conditions. 2)  Select promising cultivars and evaluate them under field 

conditions. 3)  Make initial observations on potential trap crops for SCN management.  All 

soybean cultivars tested were found to have higher SCN population densities at the end of the 

experiments, compared to the Brassica and Raphanus cultivars.  The 2017 research sites had 

greater mean numbers of SCN eggs compared to the susceptible soybean cultivars.  

Additionally, PI 88788 soybean at East Lansing in 2016 and Edwardsburg in 2017 had a greater 

reproductive factor than the susceptible soybean.  There was little variability in the impact of 

Brassica and Raphanus cultivars on SCN under greenhouse conditions.  While there was some 

variability in the field experiments, Brassica and Raphanus cultivars were often not significantly 

different from each other.  They also never resulted in more than 500 eggs per 100 cm3, which 

indicates all cultivars can safely be used in SCN infested fields.  

 

 

ACKNOWLEDGEMENTS 

 

I would like to thank Dr. George Bird for his guidance, encouragement, and patience during my 

degree program.  I would also like to thank my other graduate committee members, Dr. Chris 

Difonzo and Dr. Karen Renner for their assistance.  I want to thank Ned Birkey and Tom Kendle 

with help in selecting and planting research sites.  Additionally, Fred Warner and Angie Tenney 

of MSU Diagnostics for their invaluable advice throughout the years.  I am grateful to my friends 

and fellow students, Geof Grzesiak, Courtney Weatherbee, Kristin Poley, and Amanda Lorenz-

Reeves for their solidarity and advice.  My research was also conducted with the help of 

invaluable student workers Corey Hilton, Wesley Bird, and Lauren Rodriquez.  I am very 

thankful for the assistance they provided me throughout my research.  Finally, thank you to my 

family for supporting me through this time of my life.   

 

 

iii 

 

 

TABLE OF CONTENTS 

 

LIST OF TABLES ................................................................................................................................. v 

LIST OF FIGURES ............................................................................................................................. vii 

KEY TO ABBREVIATIONS ................................................................................................................ viii 

CHAPTER 1: Literature Review ........................................................................................................ 1 

CHAPTER 2: Reproduction of Heterodera glycines on Raphanus and Brassica Cover Crop 
Cultivars ........................................................................................................................................ 24 
Introduction ............................................................................................................................... 24 
Materials and Methods ............................................................................................................. 25 
Results ....................................................................................................................................... 35 
Discussion and Conclusion ........................................................................................................ 49 

 

APPENDICES .................................................................................................................................. 57 
APPENDIX A. Results of preliminary greenhouse trials ............................................................. 58 
APPENDIX B. Results from 2015 preliminary East Lansing field trial ........................................ 59 
APPENDIX C. Record of deposition of voucher specimens ....................................................... 60 

 

LITERATURE CITED ........................................................................................................................ 61 

 

 

 

 

 

 

iv 

LIST OF TABLES 

 

Table 1: Ten plant cultivars tested in 2016 and 2017 greenhouse and experiments. Industry 
names are followed by Latin names  ............................................................................................ 27 
 

Table 2: SCN cysts recovered from soil of soybean, radish, and mustard cultivars under 
greenhouse conditions ................................................................................................................. 36 
 

Table 3: SCN eggs recovered from soil of soybean, radish, and mustard cultivars under 
greenhouse conditions ................................................................................................................. 37 
 

Table 4: SCN eggs per cyst recovered from soil of soybean, radish, and mustard cultivars under 
greenhouse conditions ................................................................................................................. 38 
 

Table 5: SCN recovered from whole root systems of soybean, radish, and mustard cultivars 
under greenhouse conditions  ...................................................................................................... 39 
 

Table 6: SCN cysts recovered from three field sites across Michigan in 2016 ............................. 40 
 

Table 7: SCN cysts recovered from soil of soybean, radish, and mustard cultivars at three field 
sites across Michigan in 2016  ...................................................................................................... 40 
 

Table 8: SCN cysts recovered from three field sites across Michigan in 2017 ............................. 41 
 
Table 9: SCN cysts recovered from soil of soybean, radish, and mustard cultivars at three field 
sites across Michigan in 2017 ....................................................................................................... 41 
 

Table 10: SCN eggs recovered from soil of soybean, radish, and mustard cultivars at three field 
sites across Michigan in 2016 ....................................................................................................... 43 
 

Table 11: SCN eggs recovered from soil of soybean, radish, and mustard cultivars at three field 
sites across Michigan in 2017 ....................................................................................................... 43 
 

Table 12: SCN cysts recovered from soil of soybean, radish, and mustard cultivars at three field 
sites across Michigan in 2017 ....................................................................................................... 44 
 

 

v 

Table 13: SCN eggs per cyst recovered from soil of soybean, radish, and mustard cultivars at 
three field sites across Michigan in 2016 ..................................................................................... 45 
 

Table 14: SCN eggs per cyst recovered from soil of soybean, radish, and mustard cultivars at 
three field sites across Michigan in 2017 ..................................................................................... 46 
 

Table 15: Impact of soybean, radish, and mustard cultivars on Heterodera glycines reproductive 
factor under 2016 field conditions  .............................................................................................. 47 
 

Table 16: Impact of 2017 sites on Heterodera glycines on reproductive factor  ......................... 47 
 

Table 17: Impact of soybean, radish, and mustard cultivars on Heterodera glycines reproductive 
factor under 2017 field conditions  .............................................................................................. 48 
 

Table 18: Results of preliminary greenhouse experiments  ......................................................... 58 
 

Table 19: Results from the 2015 preliminary field trial at East Lansing, MI  ................................ 59 
 

Table 20: Voucher Specimens  ...................................................................................................... 60 
 

 

 

 

 

 

 

 

 

 

vi 

LIST OF FIGURES 

 

Figure 1: Susceptible soybean in conetainers after 45 days.  Photograph contains all six 
replicates of a single treatment from a single run of the host status experiment before being 
processed for SCN……………………………………………………………………………………………………………………26 
 
Figure 2: Example grid for the 2016 and 2017 field experiments. The grid is 3m2 with each plot 
within it being 1m2.  The center plot is always a susceptible soybean.  All other treatments are 
assigned a number 1-8 and randomly are distributed around the center…………………………………32 
 
Figure 3: Edwardsburg 2016 field, 90 days after planting.  Figure shows three plots on one side 
of a grid.  From Left to Right: Oilseed radish, weedy fallow, and white mustard………………………32 
 
 
 

 

 

vii 

KEY TO ABBREVIATIONS  

 
 

Pi:  Initial SCN population density at the beginning of the experiment. 

Pf: Final SCN population at the end of the experiment.   

Reproductive Factor (RF): Pf/Pi. 

Good Host:  A plant cultivar nematodes are able to increase their populations by 2-fold or 
greater.  

Moderate Host:  A plant cultivar where the nematodes are able to increase their populations by 
more than 0.10-fold but less that 2-fold.  

Poor Host: A plant cultivar where the nematodes are able to increase their populations 0.10-
fold or less. 

Non Host:  A plant cultivar where the nematodes are not able to increase their populations
 

.   

 

viii 

CHAPTER 1: 

Literature Review 

Soybean 

History - Soybeans are an important global agricultural commodity with a long history of 

use. The earliest records place their cultivation in China at around the 11th century BC 

(Hymowitz, 1970).  Soybeans were a staple food source in China and Japan for centuries. They 

eventually made their way to Europe through trade contacts in the 18th century.  Soybeans 

quickly became popular in Europe, assuring a steady demand for this crop.  Soybean uses 

expanded to animal feed, vegetable oil and many others (Hartman et al., 2011).  Soybeans were 

introduced to North America in 1765 by Samuel Bowen (Shurtleff and Akiko, 2014).  Bowen, 

was an English entrepreneur and farmer.  He settled in Savannah, Georgia.  

Henry Ford is an important figure in North American soybeans.  He was born on July 30, 

1863, on a farm in Michigan.   After his success in the automotive industry, he made it a 

personal goal to improve the quality of life for the American farmer.  To this end he sought 

agriculture crops that could be processed and converted into industrial products.  Ford believed 

that agriculture and industry were natural partners (Shurtleff and Akiko, 2014).  After 

evaluating various crops at his laboratory at Greenfield Village in Dearborn, Michigan, he 

decided that soybeans had the most potential.  Ford convinced farmers near his automotive 

plant in Ypsilanti, Michigan to grow soybeans.  This was achieved by promising them a market 

for their crops.  Concurrently, Ford’s laboratory focused on soybean industrial research.  The 

researchers quickly became pioneers for procedures and equipment for oil extraction.  The first 

 

1 

use of soybean products in the automotive industry was synthetic paints made with 35% soy 

oil.  Later, the laboratory discovered how to convert soy meal into plastic and fiber (Shurtleff 

and Akiko, 2014).   

Henry Ford’s fascination with soybeans also applied to food.  At the 1934 Chicago 

World’s Fair, he had a demonstration soybean farm.  Part of this soybean demonstration 

included a soy-based food dinner for journalists.  Ford was dressed in a suit made from soybean 

products (Shurtleff and Akiko, 2014).  He was also excited about soy milk and flour and set-up a 

soy-based bakery near his factory.  Henry Ford was fond of testing and promoting new soy 

foods.   (Shurtleff and Akiko, 2014). 

Soybean Uses - Eight countries produce about 97% of the world’s soybeans (Wrather et 

al., 2010).   In descending order these are:  The United States, Brazil, Argentina, China, India, 

Paraguay, Canada, and Bolivia.  Overall, about 6% of the world’s arable land is used for soybean 

production. This ranks soybeans as one of the most important crops globally.  About 230 million 

metric tons (MMT) of soybeans were produced in 2008 (Hartman et al., 2011), with 83.4 MMT 

produced in the U.S. (Wrather et al., 2010). The value of the U.S. 2015 crop was $35 billion 

(Ash, 2017).  Michigan grows two million acres of soybean annually.  It ranks 12th out of 31 U.S. 

soybean producing states.  In 2010, Michigan soybean export value was $589 million, more 

than that of corn (Wills, 2013).  

The high protein, low cholesterol, and low saturated fat content of soybean is the 

reason for its popularity.  It is also a source of complete protein.   Soybeans are used in many 

products.    Of all grain crops, soybean has the highest protein content (40%) and second 

 

2 

highest fat content (20%).  This makes soybeans an important plant-based food source.  Its 

protein is of high quality, making soy a key part of vegetarian diets (Raghuvanshi and Bisht, 

2010).  Soybeans are processed into meal or oil.   Soybean meal contains complete protein, 

unlike other meals.  Approximately 98% of soybean meal is used as animal feed.  About 1% is 

used for human consumption and is used in products such as soy milk and tofu (Wills, 2013).   

Soybean oil has many uses, ranging from human consumption to industrial products. 

The majority of soybean oil, (ca 88%) is consumed by humans, mostly as a vegetable oil.  The 

remaining 12% has many commercial and industrial uses (United Soybean Board 2018).   

Soybean products are becoming important alternatives to petroleum and used for biodiesel 

production (Wills, 2013).   Soybean oil is also used in the making of rubber and plastic.   

For over 60 years, soybean oil has been used as a vital ingredient in oil-based paints.    

Soy-based adhesives were developed to replace products containing formaldehyde.  The United 

Soybean Board funded research on soy-based fibers, resulting in the development of a soy-

polyethylene fiber.  Soy fiber research designed to realizing the full range of applications is still 

ongoing. (United Soybean Board, 2018).    

Cropping – Crop rotation is a common practice in soybean production. Without crop 

rotation, bean yields frequently decrease and continuous soybean cropping is usually 

considered unsustainable.    Research has shown that soybeans following crops, such as corn or 

wheat, at least once in a four-year cycle, provide as much as an 8% increase in bean yield 

(Ashworth, 2017). 

   

 

3 

Rotation crops can have profound effects on nematode populations.   Non-host crops 

can be used for management of several types of plant parasitic nematodes. Non-hosts result in 

lowering population densities through starvation (Grabau and Chen, 2016).  Each crop used in a 

rotation will change the soil-borne nematode community structure and dynamics.  This can be 

beneficial for maintaining the bacterial and fungal feeding nematodes involved in nutrient 

mineralization (Grabau and Chen, 2016: Ingham et al., 1985).   

While nematicides can be valuable in crop production, most are broad spectrum and do 

not discriminate between phytopathogenic and beneficial species.  Recent soybean-related 

research has shown that various nematicides, such as Nimitz® (Fluensulfone), greatly decreased 

populations of both bacterial and fungal feeding nematodes, which participate in nutrient 

cycling in the soil (Grabau and Chen, 2016).   

Infectious Diseases - On a global basis, there are numerous soybean diseases that 

significantly reduce bean yield.  More than 300 pathogens are known to attack soybeans. The 

majority of these however, are negligible and would likely never be noticed by soybean growers 

(Hartman and Hill, 2010).  In the U.S., the number one yield-robbing disease of soybeans is 

caused by SCN.  Other key diseases that cause problems for U.S. soybean growers include root 

and stem rots including white mold, seedling diseases, sudden death syndrome and charcoal 

rot (Wrather et al., 2010).  These will be discussed in this section, while SCN and sudden death 

syndrome are the focus of the next part of this Literature Review.  Soybean rust is an important 

infectious disease in many parts of the world. In the U.S., however, it rarely has a significant 

impact on bean yields.  Research on this disease focuses on breeding for resistance (Hartman et 

al. 2005).   

 

4 

Stem and root rots of soybeans are caused by the oomycete Phytophthora sojae 

(Kaufman & Gerdemann 1958) and the fungus Sclerotinia sclerotiorum (de Bary,1884).  In 2006, 

P. sojae was responsible for an estimated 1,424 thousand metric tons (TMT) of soybean yield 

loss and S. sclerotiorum for 362 TMT of loss (Wrather et al., 2010).  Once present, P. sojae 

quickly spreads to susceptible plants.  Fields that are most at risk have poor drainage or are 

known to flood. The water-soaked environment is optimal for the proliferation of this 

pathogen.  If infection happens soon after planting, seedlings will rot or damp-off.  In some 

cases, this can result in the need to replant the crop.  If soybean plants are established prior to 

infection, the oomycete infects the root tissue before moving into the stem, causing both stem 

and root rot.  The severity of infection and possible plant mortality relates to the genetics 

(resistance) of the cultivar.  Fields planted with cultivars without resistance can have upwards 

of 50% stand loss.  Cultivar selection is the most important management practice.  Multiple 

sources of resistance have been discovered.  Some cultivars have partial resistance.  Seed 

treatment with a fungicide is another option.  Cultural practices are also used to prevent 

establishment of the disease.  This is primarily through management designed to assure proper 

air and water drainage within the field (Dorrance et al., 2007; Hershman, 2012).   

White mold is less prevalent than other root and stem rots, but can still be significant. It 

is caused by the pathogen Sclerotinia sclerotiorum.  White mold thrives in wet fields that have 

poor drainage, similar preferred conditions as Phytophthora. White mold can be readily 

identified in the field as white, cottony mycelial growth on the host.  Symptoms begin with 

water-soaking that eventually turn into lesions.  In later stages, it causes rot and blight of the 

foliage (Heffer Link and Johnson, 2012).  Management options for white mold are similar to 

 

5 

those for Phytophthora. These include cultural controls designed to reduce field moisture and 

eliminate sources of infection. Fungicides can be applied as seed treatments and crop rotation 

helps by reducing fresh sources of inoculum.  Finally, there are resistance genes in certain host 

species and cultivars.  Use of resistant soybean varieties is always recommended (Diers et al., 

2006).   

Other soybean seedling diseases are caused by a wide variety of pathogens.  In 2006, 

these caused an estimated yield loss of 1085 TMT (Wrather et al., 2010).   For example, 

Charcoal rot, is caused by a soil-borne fungus Macrophomina phaseolina (Tassi) Goid,1947).  It 

caused nearly 700 TMT of yield losses in 2006 (Wrather et al., 2010).  Charcoal rot can be 

difficult to detect.  Many of its symptoms overlap with those of other prominent soybean 

diseases.  The pathogen thrives in hot, dry field conditions.  It is able to survive in soil in the 

absence of a host.  Infected seeds act a source of inoculum and can be difficult to detect.  As 

infection spreads, the fungus grows through the stem.  Its hyphae cause a physical impediment 

to water and nutrient uptake. There are a few management options available.   No-till systems 

have been shown to have less infection than tilled systems. Irrigation can help prevent the 

conditions conducive to infection.  Rotation with non-hosts is also another important part of 

Charcoal rot management (Smith et al., 2014).  

 

 

 

 

 

6 

Soybean Cyst Nematode 

Classification, Morphology and Pathology - SCN is a sedentary endoparasite described as 

Heterodera glycines by Ichinohe in 1952.  It is classified in the family Heteroderidae.  

Phylum: Nematoda 

Class: Chromadorea 

Subclass: Chromadoria 

Order: Tylenchida 

Infraorder: Tylenchomorpha 

Suborder: Tylenchina 

Superfamily: Tylenchoidea 

Family: Heteroderidae 

Genus: Heterodera 

Species: Heterodera glycines (Ichinohe, 1952) 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SCN is responsible for the most devastating soybean disease worldwide (Wrather et al., 

2010).  The nematode is characterized by sexual dimorphism (Hunt, 2008).    Males are 

vermiform.   Females are lemon-shaped and become protective cysts at death.  White females 

can be seen on soybean roots due to their size and distinct color.  After death, the female 

becomes a dark brown cyst (Davis and Tylka, 2000).  The metacorpus of the female esophagus 

is enlarged and fills the neck.  SCN has a terminal anus and subterminal vulva.  Males have 

strong spicules and do not have a bursa.  Second-stage juveniles have a strong stylet, with basal 

knobs. The tail uniformly tapers to a rounded end point (Hunt, 2008; Davis and Tylka, 2000).   

 

7 

History – SCN is thought to be native to the home of the soybean; China.  The earliest 

evidence for its origin is from The Annals of Liü Buwei.  One of these books mentions “three 

robbers” of crops and provides management strategies for them.  One of the robbers, “the land 

stealing the crops” is thought to be referencing soil-borne pathogens.  Soybeans are among the 

crops featured and it is suspected that SCN was one of the robbers (Riggs, 2004).   

The first modern report on SCN is from 1899 in northeastern China.  The publication 

covers a soybean disease known locally as “fire-burned seedling”.   It had been known for years.  

The symptoms of the disease and time frame of the publication led to the conclusion that SCN 

is native to China. (Riggs, 2004).  During this time frame, Japan was conducting investigations 

on a similar disease of soybeans.  A 1916 report on “Moon-night disease”, which had been 

observed since 1881, is attributed to SCN (Riggs, 2004).  In subsequent years, Moon-night 

disease was reported in several locations in Japan.  In 1951, SCN was classified, as Heterodera 

gottingiana (Liebscher 1892).  One year later, Ichinohe described SCN as a new species, 

Heterodera glycines (Ichinohe, 1952).  The reason for the initial classification was the 

morphological similarities of these two species. 

In 1954, SCN was detected in the United States, in North Carolina.  It was most likely 

introduced in the late 1930’s when a wave of nutritional deficiencies afflicted soybean crops.  

While symptoms of SCN damage were first observed in North Carolina, within a few years, it 

was reported from surrounding states (Riggs, 2004).  As of 2017, SCN has been confirmed in all 

soybean producing regions of the U.S. (Tylka and Marett, 2017).   

 

 

8 

The speed at which SCN detection increased inhibited investigating SCN’s origin in the 

U.S.   The introduction was most likely from infested soil.  The 1954 confirmation was from a 

field containing bulb-grown flowers, some of which came from Japan.  Another possible source 

was the practice of dusting soybean fields with soil taken from Japanese soybean cultivar sites.  

This process was used to introduce Bradyrhizobium, a nitrogen-fixing bacterium.  Introductions 

and movement of soil and soybeans across North America, however, make it impossible to 

know the actual source of SCN (Riggs, 2004).  

SCN was first detected in Michigan in 1987, in Gratiot County (Warner and Bird, 2000).  

Since 1987, it has spread to every soybean producing county in Michigan’s lower peninsula, 

except Presque Isle.  It causes an estimated $40 million in losses a year in Michigan (Tylka and 

Marett, 2017). 

2018 Distribution – SCN has a worldwide distribution.  It can survive a wide range of 

environmental conditions.  It is known to be present in many countries where soybeans are 

prominent, including Japan, China, Brazil, Canada, and the United States (Wrather et al., 2010).  

It has been confirmed in most soybean producing states and spreads to new counties every 

year.  In 2017, a total of 37 new counties were added to the United States SCN distribution.  It is 

currently the leading cause of soybean yield losses in the U.S. (Tylka and Marett, 2017: 

thescncoalition.com).  

Host Range – SCN has a relatively wide host range.  Many leguminous plants are hosts, 

including hairy vetch, mung beans, snap bean and pigeon pea.   Some members of the 

Caryophyllaceae, such as common chickweed, figworts, common mullein, purple deadnettle 

 

9 

and other flowering annual plants have also been confirmed as hosts (Hunt, 2008).  Many of 

these, such as common chickweed and purple deadnettle, can be found in Michigan fields.  

Some populations have the ability to reproduce on sugar beets and certain tomato cultivars 

(Riggs, 2004).  Fortunately, Graminaceae spp. are not hosts of SCN. 

Life Cycle – The life cycle of SCN can be complete in 30 days or less under optimal 

environmental conditions.  They thrive at temperatures between 28-31C.  The first molt, first-

stage juvenile (J1) to second-stage juvenile (J2), takes place in the egg, in the cyst.  When the 

correct chemical cues are received, the J2s emerge from the egg and then the cyst.  The J2s 

follow chemical cues to the root zone of an appropriate host (Hunt, 2008; Davis and Tylka, 

2000).  Once a plant host root system is located, the juvenile penetrates the root tissue through 

use of its stylet.  It migrates intracellularly, seeking the vascular cylinder.  When an appropriate 

feeding site is reached, the J2 nematode adopts a sedentary lifestyle.  Secretions from the 

nematode results in the formation of specialized feeding cells that sustain juveniles through the 

sausage-shape J2, the swollen J3 and J4 stages and into early adulthood (Hunt, 2008: Davis and 

Tylka, 2000). 

SCN females remain at the feeding site for their entire adult lives.  As SCN goes through 

its juvenile stages, it becomes progressively larger, assuming a sausage shape (Hunt, 2008).  At 

the final molt into adulthood, the female is white and lemon shaped.  Females produce 200-250 

eggs.  Most of the eggs are stored in the female’s body cavity (Davis and Tylka, 2000). Other 

eggs are deposited outside of the female in a gelatinous matrix.  After death, the female body 

hardens, forming a cyst and becomes a protective barrier that assists in prolonging egg viability.  

SCN eggs can be viable for up to 20 years (Hunt, 2008: Davis and Tylka, 2000). It is interesting to 

 

10 

note that in 2018, it was reported that a currently unidentified nematode species remained 

viable for more than 40,000 years in Siberian permafrost (Siberian Times, 2018).     

SCN males feed on the nurse cells through the J4 stage.  At this time, they undergo 

metamorphosis and become vermiform males.  Males exit the root tissue. They move 

throughout the rhizosphere, fertilizing any adult female SCN they come across, until their death 

(Hunt, 2008: Davis and Tylka, 2000). 

Symptomology – Symptomology is dependent on the severity of infection and 

environmental conditions.  Light to moderate SCN population densities may result in few or no 

symptoms.  Fields with fine textured (clay or silt) soils and adequate moisture are often unlikely 

to have above ground symptoms from SCN.  Stunting and yellowing are the most common 

symptoms.  Fields with high populations and sandy, dry soil tend to see more severe above 

ground symptoms and sometimes even plant death.  In these fields, plants will be yellow and 

stunted.  Root systems are usually stunted and often lack nitrogen-fixing nodules (Davis and 

Tylka, 2000). 

Disease Complex – Under field conditions, Sudden Death Syndrome (SDS) is usually a 

soybean disease complex caused by the interaction of SCN and the fungal pathogen Fusarium 

virguliforme (Aoki et al., 2003).  SDS was first discovered in Arkansas in 1971 and has since 

spread across the United States.  F. virguliforme is the primary causal agent of SDS.  When SCN 

is present, SDS symptoms are more severe and occur earlier in the season.  Due to this 

complex, managing SCN is an important aspect of SDS management (Westphal et al., 2008).  It 

 

11 

has been suggested that the SCN female body may serve as on over-wintering protective body 

for the fungus (Personal Communication, George Bird, 2018).   

While SDS management options exist, there is a need to continue investigating new 

control practices.  The genomes of both soybean and F. virguliforme have been sequenced.  

Due to this development, biotechnology is likely to play a role in the future of SDS 

management.   There is current promising research on SDS management, including plant stress 

response and F. virguliforme resistance in soybeans (Hartman et al., 2015). 

Management – The best SCN management strategy is avoidance.  Since the eggs of this 

nematode can remain viable in protective cysts in soil for as long as 20 years, population 

reduction is a challenge.  Good management practices that reduce risk of infestation include, 

cleaning equipment to avoid transfer of SCN between fields and use of SCN-free seed (Warner 

and Bird, 2016).  Unfortunately, more than 50% of the soybean fields in Michigan have already 

been infested with SCN (Schumacher-Lott, 2011).   

SCN Scouting - SCN scouting is essential for formulating an appropriate management 

plan. Typical SCN scouting (nematode sampling) involves taking as many soil cores as practical 

at random from the field or a specific portion of the field (Perez-Hernandez and Giesler, 2017). 

The fall is the optimal time to sample.   These cores are then mixed before SCN extraction in 

order to homogenize the soil samples.  This process is important to account for the nematode 

variability within locations (Perez-Hernandez and Giesler, 2017).  The SCN coalition also outlines 

this information, and will be discussed in a later paragraph. 

 

 

12 

SCN Management - Crop rotation is an important aspect of a SCN management plan.  

One to two years of a non-host crop is recommended.  While SCN eggs in cysts can remain 

viable as much as 20 years, egg viability decreases in the absence of a host by about 20% per 

year (Davis and Tylka, 2000).  It should be noted, however, that these decreases are 

unpredictable and are heavily dependent upon environmental conditions (Davis and Tylka, 

2000).   Corn and wheat are commonly used as rotation crops in Michigan soybean systems. 

Sugar beet is also an option in parts of the state. 

Use of SCN resistant cultivars is the most common SCN control procedure used, usually 

in conjunction with crop rotation.  While over 100 genetic sources of SCN resistance have been 

identified, only seven have been developed for sale in commercial cultivars (Mitchum, 2016).  

Only three, however, are currently commercialized for use in soybean cultivars grown in the 

North Central region of North America.  These sources are PI 548402 (Peking), PI 88788, and PI 

437654.  Most states, including Michigan, have used cultivars from a single source of resistance, 

PI 88788, for the past 20 years.  In some years, as much as 95% of the market share in the North 

Central United States came from this line (Mitchum, 2016).  Overuse of a single source of 

resistance has led to highly aggressive SCN populations.  Research has shown that PI 88788 in 

particular is becoming less effective and resulting in increases in SCN reproduction (McCarville 

et al., 2017).  In 2018, a new SCN Coalition was formed to combat this problem.  The SCN 

coalition is a partnership of universities from 27 states and Ontario, checkoff organizations, and 

the agricultural industry (Begeman, 2018).  Additional information about the Coalition can be 

accessed at www.scncoalition.com.  

 

 

13 

According to the SCN Coalition the majority of soybeans planted in the Midwest derive 

their resistance from PI 88788, since that is what readily available.  Soybean cultivars with 

PI88788 resistance use multiple copies of the rhg1 locus in order to convey resistance. There is 

evidence that when multiple copies of this gene are present, there is greater nematode 

suppression (Cook et al., 2012).  Cultivars with PI 548402 (Peking) resistance employ two genes 

for resistance.  This requires Rhg1 and Rhg4 to convey resistance (Lee et al., 2015).  PI 437654 

resistance is also found primarily on the Rhg1 and Rhg4, although there are five minor locus 

that have been mapped and are thought to be involved (Concibidio et al., 2004).  Studies 

suggests that there are different functional alleles for Rhg1 on PI 88788 and PI 437654 (Brucker 

et al., 2005).  

In order to halt development of aggressive SCN populations, alternate sources of 

resistance need to be incorporated into commercial cultivars.  In many cases it has been 

difficult to breed for both SCN resistance and superior agronomic traits.  Frequently, alternate 

sources of resistance have resulted in “yield drag”.  This issue needs to be resolved.   

Researchers are currently investigating increasing effectiveness by stacking Rhg1 and Rhg4 as, 

well increasing the number of Rhg1 copies (Mitchum, 2016).   

An additional management strategy is the promotion of suppressive soils.  It has been 

observed that a long-term soybean monoculture (> 6 years) can result in a decrease in in soil-

borne pathogens (Hamid et al., 2017).   Continuous soybean cropping can result in soils 

suppressive to SCN.  A suppressive soil is defined as when a pathogen is present but causes 

little crop damage due to the presence of antagonistic organisms.  This has been observed in 

some long-term soybean production systems in China and the United States since the 1980’s 

 

14 

(Chen, 2006).   One question researchers have tried to answer is what specific organisms and 

processes cause this phenomenon.   As a result of continuous cropping, there is a shift in the 

microbiota composition of the soil microbiome.  This shift causes a rise in the abundance and 

diversity of pathogen suppressive microbial species (Hamid et al., 2016).   A group of 

researchers have compared fungal populations in a continuous soybean field with a soy-corn-

wheat rotation (Li et al., 2016).  The researchers looked for parasitic fungi within SCN cysts.  It 

was found that in the continuous soybean field there was an increase in the diversity of SCN-

parasitic fungi, as well as higher populations of those fungi, compared to the rotation.    

Bacterial population density and diversity can play a similar role in regards to development of 

suppressive soil (Hu et al., 2017).  Microbial communities and their diversity are an important 

component in the formation of suppressive soils (Li et al., 2016; Hu et al., 2017).  

Cover Crops 

A cover crop is a plant that is grown to provide one or several agronomic, soil health or 

pest protection benefits.  Cover crop use is increasing in the U.S. but is still slow to be 

incorporated into the Midwest.  According to a 2015 survey of corn and soybean acres cover 

crops were used on 2.3% of the acreage in Illinois, 2.6% in Iowa, and 7.1% in Indiana (Rundquist 

and Carlson, 2017).    Cover cropping is a complex management strategy and its effectiveness 

depends on many factors.  Soil type, microbiota, field history, and crops present are all factors 

that influence the effect that cover crops have on soil health (Bowman et al., 2007). It is also 

necessary to identify specific objectives and select specific cover crop cultivars to achieve them.  

Cover crops can be planted individually or as blends of cultivars or plant species.  Additionally, it 

is also important to consider planting date, life cycle, and the environmental tolerances of a 

 

15 

potential cover crop to make sure it will survive and fulfill the objective (Jimenez-Alfaro et al., 

2018).   In some cases, it is possible to inter-seed cover crops with the cash crop.  While cover 

crops are used by a significant number of Michigan farmers, cover crops are starting to be used 

in soybean systems (Davis, 2010).   An important element in cover crop usage is that it needs to 

fit into the crop rotation.  In the Midwest this can be difficult in systems that only use corn and 

soybean due to the lateness of harvest.  Introducing a crop that comes off earlier, opening a 

window for cover crop planting in August, such as wheat, cucumbers, dry beans, or seed corn 

creates a cover crop seeding opportunity. Iowa in particular has many sources provided by the 

Practical Farmers of Iowa (Rundquist and Carlson, 2017).  

There are many reasons for using a cover crop and some cultivars provide multiple 

benefits.  If a rotation leaves a field fallow, a cover crop will prevent wind and rain erosion.  It 

has been shown that using certain cover crops, such as barley and vetch, can increase the water 

holding capacity of soil while also being able reduce nitrate leaching when compared to a 

winter fallow field. (Garcia-Gonzalez et al., 2018). Building organic matter is another important 

function and is the reason cover crops are also known as “green manures”.  Organic matter 

building is especially vital when the majority of plant material is removed during harvest.  

Legumes comprise a significant number of available cover crops and are valued for nitrogen 

fixation (Curran et al., 2006: Clark, 2015).  Nutrient scavenging (fixation) is another reason for 

using a cover crop.  Nutrient loss in groundwater under fall, winter, and spring conditions can 

be reduced through successful cover crop use.  Habitat establishment for promotion of 

beneficial organisms is a benefit of cover crops that has been a focus in recent years.  This 

includes the establishment of natural pollinators, predators, earthworms, and microorganisms 

 

16 

that can provide long-term benefits to a cropping system.  Weed suppression can also be 

obtained through cover cropping since they provide additional resource competition (Curran et 

al., 2006: Clark, 2015).  The effects of cover crops on soil pore size has also been examined.  Soil 

pore parameters can be important factors in soil health and can affect soil temperatures and 

water infiltration.   The cover crops tested included, hairy vetch (Vicia villosa), cereal rye (Secale 

cereale), and Austrian winter pea (Pisum sativum subsp. Arvense).  All of the cover crops tested 

resulted in an increase in the number of macropores from 25 to 75% when compared to the no-

cover treatments.  This recent study shows that cover crops can have positive soil health effects 

by affecting soil pore parameters (Cercioglu et al., 2018).   

Due to the variety of uses and types of cover crops, farmers must have an objective or 

reason for wanting to plant a cover crop so the correct cover crop(s) can be selected. Therefore, 

the first and most important step is to identify the purpose or objective for seeding the cover 

crop.  The next step is to select the proper cultivar to achieve the desired objective. Lastly, the 

cover crop must be managed in a way designed to achieve the objective (Personal 

Communication George Bird, 2017).    

Farmers have difficulty in fitting a cover crop into their crop rotation, in particular, if the 

farmer in growing only corn, or corn and soybeans.  Finding a time to seed the cover crop 

(frequently called a window) is difficult (Clark, 2015).  In addition, it is important to know how a 

selected cover crop should be terminated.  It is important to insure some species don’t go to 

seed because the cover crop could potentially become a weed in subsequent crops. Herbicides, 

mowing, or tillage can be used to prevent this.  Alternatively, fall seeding of a winter-killed 

cover crop can achieve this without additional cost and time, but this results in no cover during 

 

17 

spring which may lead to soil erosion from spring winds and rains.  Finally, it is important to 

know which pathogens are present and how they will interact with the cover crop.  Planting 

cover crops that are a host for certain pathogens may offset the benefits of the cover crop 

(Curran et al., 2006).   

There are multiple ways to seed cover crops.  Tillage prior to seeding is recommended 

for some cover crops as it prepares a seedbed and disrupts established weeds.  Cereal rye and 

small grains, however, can benefit from a no-till approach.  No-till plantings are recommended 

for late plantings or where erosion is a major concern.  No-till drills are used to ensure 

uniformity, depth, and proper soil contact (Curran et al., 2006).  Planting depth is determined 

by the cover crop seed size (Curran et al., 2006). 

Broadcast seeding has the lowest rate of establishment of the cover crop planting 

methods.  This method works best with small sized seeds.  Multiple seedings may be needed to 

get an adequate stand.  Aerial seeding can be used to cover large acreages.  Aerial seeding or 

high clearance broadcast seeding are necessary methods of inter-seeding a field where another 

crop is already established (Curran et al., 2006). 

There are multiple ways cover crops influence various types of organisms.  Rivers et al. 

(2018) examined the use of cover crops in a wheat-corn-soybean rotation to promote 

arthropod predators.  The planting time of these cover crops occurred after wheat harvest for 

one crop and after corn harvest for the second.  Cover crops were planted in the fall and roller-

crimper terminated in the spring.  The presence of cover crops increased the abundance of 

arthropod predators in the immediate area (Rivers et al., 2018).   

 

18 

A South African study examined the effect of various Brassica and Raphanus cover crops 

managed for biofumigant properties on the development of various Meloidogyne spp. 

populations.  One cultivar examined was Terranova radish, which is included in my SCN thesis 

research (Daneel, et al., 2018).  The effect of the cover crops on nematode species was variable 

both between the cover crops tested as well as the Meloidogyne sp.  used.  Terranova radish 

did not result in significant changes in the Meloidogyne populations (Daneel, et al., 2018).   

Many options are available for cover crop selection.  The most common include legume, 

Graminaceae and brassica species.   Common winter annuals include crimson clover, hairy 

vetch, fields peas, etc.  Perennials include red or white clover.  Sweet clover is used as a 

biennial.  Cowpeas are grown as a winter annual (Clark, 2012).  Grasses make up another major 

group of available cover crops.  They are often used as an annual cover crop.  Cereal rye, spring 

oats, sorghum-Sudan grass, and annual ryegrasses are found under this category (Curran et al., 

2006). A wide variety of brassicas are used for nutrient scavenging, reduction of soil compaction 

and biofumigation.  Cultivars of rape, kale, turnip, and radish are available.  Some of these 

cover crops also have the possibility of being harvested to help recoup seed costs.  Buckwheat 

is another prominent cover crop that doesn’t fall into the categories discussed above (Curran et 

al., 2006). 

   

Cover Crops and Nematodes – Nematodes fill a wide range of niches in the soil and are 

involved in the transport and transformation of matter and energy among plants, fungi and 

bacteria.  The majority of soil-borne nematodes are beneficial.  Nematode community 

 

19 

composition is dependent on the soil and environment, including primary producers.    Adding 

cover crops to a rotation increases the soil biodiversity and thus impacts nematode community 

structure and population dynamics.  The addition of soil organic matter results in increases in 

fungal and bacterial decomposers and both fungal and bacterial feeding nematodes. (Warner 

and Bird 2018). 

There has been a significant amount of research on the effect of cover cropping on 

nematode populations.  This includes both plant parasitic and beneficial species (Ito et al., 

2015).  Increased microbial diversity allows for a positive response to soil-borne pathogens. As 

diversity increases, the likelihood of organisms antagonistic to pathogens increases.  There are 

many roles that need to be filled in the soil food web for proper nutrient cycling and 

decomposition.   Promoting soil biological diversity helps ensure these are filled (Ito et al., 

2015). 

Specific cover crops reduce certain parasitic nematode populations.  The most common 

method to achieve this is through use of a non-host cover crop.  Non-hosts act as pest-starvers.  

These, however, are less effective for cyst nematodes because of the long viability in cysts in 

soil (Warner and Bird 2018, Bessey 1911). 

 

Brassica and Raphanus species can be managed as biofumigant crops by incorporating their 

foliage into soil.  Mustards, radishes, rapeseed and others contain a high level of glucosinolates.  

These are volatile chemicals released when plant material is damaged or decomposed.  At high 

 

20 

concentrations these chemicals are toxic and provide localized pest suppression (Fourie et al., 

2015).   

There are multiple species of the genus Raphanus (radish) and at least four subspecies 

of R. sativus. These include R. sativus sativus (garden radish), R. sativus oleiferus (oilseed 

radish), R. sativus longipinnatus (daikon radish) and R. sativus niger (horse radish). Daikon and 

oilseed radish are used as cover crops. A few cultivars of oilseed radish are used as trap crops in 

sugar beet systems. Mustards are highly variable and include Ethiopian mustard (Brassica 

carinata), wild mustard (Sinapis arvensis), White mustard (Sinapis alba), Yellow mustard 

(Brassica hirta), Brown/Oriental/ Indian mustard (Brassica juncea) and Black mustard (Brassica 

nigra).  Various mustards have been used as cover crops and for biofumigation. 

 

Trap Crops 

Trap crops are plants that attract and prevent the reproduction of pathogens and pests.  

They may be cash crops or cover crops.  The concept of trap crops began about 100 years ago.  

German scientists noticed sugar beet failures were being caused by nematodes.  To combat 

this, they planted crops that were a host for the nematode and then terminated the crop 

before completion of the nematode’s life cycle (Bessey, 1911).  This is referred to as a Category 

1 Trap Crop.  The German researchers used summer rapeseed for the trap crop.  When the 

process was repeated multiple times a year, there was a decrease of pest pressure on sugar 

beets in subsequent years (Bessey, 1911).  In more recent times, garden radish has been used 

as a trap crop to manage Meloidogyne spp.  The radishes are harvested prior to completion of 

the nematode life cycle. 

 

21 

Category 2 Trap Crops also attract and prevent reproduction of the target pest. For 

nematode management, Category 2 Trap Crops release appropriate cues to stimulate the 

emergence of the J2’s from eggs and cysts.  The nematodes are attracted to and penetrate root 

tissue.  They locate a potential feeding site and attempt to incite nurse cell formation.  The trap 

crop fails to respond to this stimulus and nurse cells are not formed.  This results in nematode 

starvation of females before reproduction, thus preventing the next SCN generation. 

Research on nematode trap crops has been undertaken in several laboratories.  This 

includes, but is not limited to, SCN, Heterodera schachtii (Beet Cyst Nematode), Globodera 

pallida (potato cyst nematode), and Meloidogyne hapla (northern root-knot nematode).   

Several commercial oilseed radish cultivars have been developed as trap crops for beet cyst 

nematode. (Smith et al., 2004: Peterka, 2004).  Potato cyst nematode is a severe pest and a 

quarantine species in many parts of the world.  Due to this, it is receiving a lot of research 

attention, particularly in Europe.  Many members of the nightshade family have been explored 

and recommended as trap crops for BCN (Scholte and Vos, 2005: Timmermans et al., 2007).  

Historically, garden radish has successfully been used as a trap crop for root-knot nematodes 

(Meloidogyne spp.) since the plant has a shorter life cycle than the nematode. 

 

Control of SCN can be difficult. Using cover crops adds more variables into the 

production system.  Many cash crops, cover crops, and weeds are hosts of SCN.  These serve to 

increase SCN populations even when soybeans are not present.  Care needs to be taken in 

cover crop selection.  If a host is used then it needs to be terminated before SCN reproduction 

 

22 

occurs. This allows for cover crops to be used as Category 1 Trap Crops.  Additionally, some 

cover crop cultivars act as Category 2 Trap Crops for specific nematode species.  For example, 

specific cultivars of oil seed radish have been developed for control of beet cyst nematode.  

These trap crops act as alternate hosts that will attract second stage juveniles, but not allow 

females to fully develop and reproduce.  This research MS. thesis research evaluates  the SCN 

host status of several Brassica and Raphanus cultivars as well exploring them as potential 

Category 2 Trap Crops for SCN management.  

 

 

 

 

 

 

 

 

 

 

 

 

23 

CHAPTER 2: 

Reproduction of Heterodera glycines on Raphanus and Brassica Cover Crop 

Cultivars 

 

Introduction 

Soybeans (Glycines max) originated in China in 2800 B.C. (Hymowitz, 1970).  Today, 

soybean is a dietary and economic staple in many parts of the world.  The United States ranks 

as the top single soybean producer but is eclipsed by the combined production of Brazil and 

Argentina, with Brazil itself expected to take the lead in the coming years (George et al., 2018). 

There are many challenges to successfully growing soybeans, including a diverse array of pests 

and diseases.    

Heterodera glycines (Ichinohe, 1952), commonly known as soybean cyst nematode 

(SCN), has been a major problem for soybean growers in the United States since the 1950’s.   

SCN can be extremely devastating.  Soybean (Glycines max) yield losses can be as high as 75% in 

heavily infested fields, with an estimated $500 million loss annually in the United States.  The 

most common and effective methods of control are resistant soybean varieties and use of non-

hosts in crop rotation systems.  While there are effective H. glycines (SCN) management 

practices, there is a pressing need to explore new technologies.  Heterodera schachtii (sugar 

beet cyst nematode) is successfully managed with trap crop cultivars of Brassica species.  

Seeding Brassica and Raphanus cover crops for maintaining and renovating soil health is 

increasing in the United States (Roesch-McNally et al., 2017), but there is limited research on 

how these cover crops influence SCN population development (Leslie et al., 2017).   

 

24 

The objectives of this M.S. Thesis are to: 1) determine the impact of Brassica and 

Raphanus cultivars on SCN population dynamics, 2) determine the suitability of using Brassica 

and Raphanus cultivars as cover crops in SCN infested sites, and 3) attempt to identify 

appropriate Brassica and Raphanus cultivars as trap crops for SCN management.   

Materials and Methods 

The research was conducted in 2016 and 2017 in multiple experiments in the G. W. Bird 

Laboratory Nematology greenhouse and laboratory at Michigan State University.  In addition, 

field research was done in 2015, 2016 and 2017 at three widely distributed commercial 

soybean sites in Michigan.   One 2015 field experiment and four 2015 greenhouse runs were 

preliminary.  These were considered failures and were used to develop research methodology.  

The results from the preliminary trials are included in Appendices A and B.  In the main body of 

research, two mustards (Hood River Seeds, Evansville, IN) (white and Ethiopian), and two radish 

subspecies (Center Seeds, Sidney, OH), (daikon and oilseed), were selected for study.  Several 

susceptible and resistant soybean cultivars were also selected (DF Seeds, Dansville, MI).  For 

this paper the terms Brassica and Raphanus are used to refer to these radishes and mustards.  

Greenhouse Research 

Overview:  Experiments were conducted at the MSU Plant Science greenhouses 

(42°43'17.2"N 84°28'34.5"W).  Experiments where conducted in the greenhouse over the 

course of nine runs.  Runs occurred during the fall and winter of 2016 and 2017.  A max of two 

runs occupied the greenhouse at one time and were staggered so they were not terminated at 

the same time. A randomized complete block design was used with each treatment (plant 

 

25 

cultivar) replicated six times in a single run.  Conetainers, 20.95 cm x 4.12 cm, were used as 

vessels for growing the plants (Figure 1.).  The conetainers were filled with media consisting of 

50% playground sand and 50% mixed soil, provided by the MSU greenhouse, until one inch of 

empty space remained at the top.  Each conetainer held 100 cm3 of soil.  Ten cultivars were 

evaluated in the final greenhouse experiments (Table 1).  All seeds were provided either by the 

Michigan State University Plant Science and Microbial Sciences departments or Center Seeds.       

Figure 1: Susceptible soybean in conetainers after 45 days.  Photograph contains all six 
replicates of a single treatment from a single run of the host status experiment before being 
processed for SCN. 

 

Plant Inoculation:   SCN inoculant for greenhouse research was collected from 

greenhouse cultures. The cultures originated from an SCN population at the Michigan State 

University Department of Entomology Research Farm, East Lansing, Michigan (42°41'25.8"N 

84°29'53.0"W). SCN cultures were established on susceptible soybean (DF 155) and allowed to 

 

 

26 

increase for four months.  One teaspoon of slow release fertilizer pellets (20-20-20) were added 

once every month to the soybeans of these cultures.  SCN cysts were recovered using a 

modified centrifugal flotation method (Jenkins, 1964), using a heavy sugar solution, consisting 

of 1845 grams of sugar dissolved in 3.8L of water.  The cysts recovered were examined using an 

inverted microscope (Nikon TMS, 20x).  Based on the available inoculant and estimated number 

of SCN eggs/cyst, an inoculation standard of 20 cysts (40 eggs/cyst) per 1 ml of water was 

established.  In the field this would be above the danger threshold of 500 eggs per 100 cm3 of 

soil. 

Table 1: Ten plant cultivars tested in 2016 and 2017 greenhouse and experiments. Industry 
names are followed by Latin names. 

1)      Susceptible Soybeans 
                  DF5242R2Y® 
                  DF155® 
2)      Resistant Soybeans 
                   INA® - PI 437654 x PI 88788 
                   DF242N® – PI88788 
3)      Biofum Summer® (Blend) 
                   50% Brassica carinata 
                   40% Raphanus sativus subsp.  oleifera 
                   10%  Sinapis alba 
4)      Ground Hog® Daikon Radish –  
                    Raphaus sativus subsp.  longipinnatus 
5)      Cappuchino® Ethiopian Mustard – 
                    Brassica carinata 
6)    Image® oil seed radish 
                    Raphanus sativus subsp. oleifera 
7)      Braco® White Mustard- 
                 Sinapis alba 
8)      Defender® oil seed radish – 
                 Raphanus sativus subsp. oleifera 
9)   Action® White Mustard – 
                  Sinapis alba 
10)   Maximus® Fodder Radish –  
                   Raphanus sativus subsp. oleifera 

27 

 

Seeds of the eight Brassica and Raphanus cover crop cultivars selected for evaluation 

were germinated for two days at room temperature in a petri dish containing damp tissue 

paper.   After germination, a single seedling was planted in each conetainer in a depression in 

the media made using a glass rod.  Twenty SCN cysts in 1.0 ml of water were added 

immediately to the future rhizosphere of the seedlings with a disposable plastic syringe.  The 

conetainers were placed in the greenhouse growing area.  This process was used for all runs.  

Plant Growth: Four Brassica and Raphanus and two soybean cultivars (SCN susceptible 

and SCN resistant) were used in eight of the runs.  Five Brassica and Raphanus cultivars were 

included in the two runs. This was done to try to keep the number of treatments balanced.  

Despite this some treatments were removed due to having few replicates surviving.   The 

Brassica and Raphanus cultivars were selected because of their potential as SCN trap crops.  In 

every experiment, each cultivar was replicated six times.  The containers were split into blocks, 

randomly arranged, and placed in half of a conetainer rack.  The racks were maintained in the 

greenhouse for45 days.  Plants were under 16 hours of light, maintained at 26-28 C, and 

watered once per day.   PAR measurements were not taken. Plants were terminated after 45 

days and SCN were extracted.  Due to SCN’s 30 days lifecycle this would ensure that SCN were 

in the second generation and would be present in the roots for staining.    

SCN Extraction and Population Analysis: After 45 days, the soil and plants were 

removed from the conetainers.  This was followed by gently removing the root systems from 

the soil.  The roots were then rinsed and stored (4.4 C) for future root staining.  SCN cysts were 

extracted from the entire volume (100 cm3) of the media in each conetainer using the modified 

centrifugal flotation method (Jenkins, 1964), placing the 100 cm3 of media in a bucket before 

 

28 

adding three to four liters of water and mixing thoroughly. The solution was filtered using a 16-

mesh over a 400-mesh sieve.  The 16-mesh sieve was used to remove large debris.  Media 

collected in the 400-mesh sieve was rinsed into a centrifuge tube.  The sample was re-

suspended using a spatula.  The samples were then centrifuged at 4000 rpm for four minutes.  

The supernatant water was decanted and the sucrose solution added.  The media was re-

suspended using a spatula then centrifuged at 4000 rpm for two minutes.  A 400-mesh sieve 

was used to collect the SCN cysts.  The sieve was washed with tap water for 30 seconds to 

remove any remaining sucrose solution.  The cysts were funneled into a test tube.  The resulting 

samples consisted of SCN cysts and eggs in ~5.0 ml of water.  Each sample was poured into a 

petri dish divided into ten segments to ensure accurate nematode population density 

determination.  After all cysts were counted, the sample was funneled into a tissue macerator.  

Samples were ground for 20-30 seconds to break the cysts and leave the eggs undamaged. Each 

sample was poured into a 50.0 ml beaker.  The tissue macerator was rinsed into this beaker and 

the sample diluted to 20.0 ml.  A 1.0 ml aliquot was used to estimate the number of eggs in a 

sample.  The SCN cysts and eggs were counted under a Nikon TMS, 20x inverted microscope. 

Root systems were stained within one week after terminating the experiment using the 

procedure of Byrd et al. (1983).   The entire root systems were placed in 600 ml flasks 

containing 50 ml of a 1:1 solution of Chlorox Regular Bleach and DI H2O.  They were soaked for 

four minutes with occasional agitation.  Afterwards, they were rinsed with tap water to remove 

any remaining solution.  Rinsed roots were soaked in tap water for 15 minutes to remove any 

remaining solution.  Roots were then placed into 100 ml beakers in 30-50 ml of water 

containing a 1.0-2.0 ml stock acid-fuchsin-stain solution. The beakers were brought to a boil 

 

29 

using a hotplate set to high.  Boiling occurred for 30-60 seconds before beakers were removed 

from the hotplate and allowed to cool for ten minutes.  Roots were rinsed with tap water and 

added to beakers containing 50 ml of acidified glycerin.  The acidified glycerin was brought to a 

boil for 30-60 seconds before being removed from the hotplate.  Roots were allowed to cool to 

room temperature before being examined. Three-to- four-cm-long root segments were 

inserted between two glass discs until all root segments were examined.  Samples were 

inspected (Nikon SMZ18, 10x) for juvenile and adult nematodes.  Nematodes observed were 

categorized by body shape (vermiform, sausage-shape or lemon-shape).  This data was not 

presented due to all SCN observed on Brassica and Raphanus being vermiform. 

Field Experiments: 

Overview:  Field research was conducted in 2016, and 2017.    A preliminary 2015 

experiment can be found in Appendix B.  The 2016 and 2017 experiments were conducted in 

East Lansing, Dundee, and Edwardsburg MI. All experiments used a randomized complete block 

design.   All seeds were planted at the following rates: 6.0 lb/A for Brassica, 8 lb/A for Raphanus 

and 140,000 seeds/A for soybeans.  This was determined from recommendations from 

Michigan State University Extension.   

2016 and 2017 Field Experiments: 

Locations:  The 2016 field experiments were located at East Lansing, MI (42°41'25.8"N 

84°29'53.0"W), Edwardsburg MI, (41°46'38.1"N 86°04'16.1"W), and Dundee, MI (41°56'42.8"N 

83°39'08.4"W). The 2017 field experiments were located at East Lansing, Mi (42°41'25.8"N 

84°29'53.0"W), Edwardsburg, Mi (41°46'38.1"N 86°04'16.1"W), and Dundee, Mi (41°59'24.9"N 

 

30 

83°43'50.9"W).   All plantings occurred before August 15th, which is after winter wheat is 

harvested and a cover crop window in Michigan soybean production.   

Planting:  Each cultivar was replicated six times in a randomized complete block design.  

Each block was 3.0 m2, separated into nine 1.0 m2 plots (Figure 2).  Each segment contained one 

of three SCN controls and six Brassica and Raphanus cultivars chosen based on preliminary 

greenhouse data and the 2015 field experiment.  One of the treatments was a SCN susceptible 

soybean cultivar.  It was always located in the center plot. Also included was an SCN resistant 

soybean cultivar, a weedy fallow, and five Brassica and Raphanus cultivars.  Since SCN only 

move a few cm in their lifetime this allows for a greater statistical analysis, as the population 

numbers in each plot are more likely to be similar.  Soybean cultivars and resistance sources 

were chosen due to being commonly available and used in Michigan.  This was done to better 

understand how treatments would work in current soybean systems.  While the center 

segment in all six replicates was always the SCN susceptible control, the locations of the other 

eight plots were randomly assigned.  All plantings were done in early August, to mimic the time 

farmers plant cover crops after harvesting winter wheat in Michigan.  All seeds were planted by 

hand at the following rates: 6.0 lb/A for Brassica, 8 lb/A for Raphanus and 140,000 seeds/A for 

soybeans.   

 

 

 

 

 

 

 

31 

Figure 2: Example grid for the 2016 and 2017 field experiments. The grid is 3m2 with each plot 
within it being 1m2.  The center plot is always a susceptible soybean.  All other treatments are 
assigned a number 1-8 and randomly are distributed around the center.   

3 

6 

5 

8 

Susceptible 

2 

1 

4 

7 

 

Figure 3: Edwardsburg 2016 field, 90 days after planting.  Figure shows three plots on one 
side of a grid.  From Left to Right: Oilseed radish, weedy fallow, and white mustard.  

 

 

 

32 

 

Plant Growing Phase: Plots were not managed after planting.  No fertilizer was applied 

and no weed management practices employed.  Visual estimates put weed biomass as 30% of 

the plots in 2016 and 10% in 2017. At the end of the season the experimental plots were left to 

winter kill.   

Post-Harvest Phase:  Three soil samples were taken from each plot at each location at 

the time of planting, and 45 and 90 days after planting. These were then homogenized before 

nematode extraction.   Of the soil collected, 100 cm3 was processed and cysts extracted using 

the modified centrifugal flotation method (Jenkins, 1964). One hundred cm3 of soil was placed 

in a bucket with three to four liters of water and mixed thoroughly. The solution was filtered 

using a 16-mesh over a 400-mesh sieve.  The 16-mesh sieve was used to remove large debris.  

Nematode numbers were determined using the methods previously described.  Plant biomass 

was considered as a part of this experiment.   

Statistical Analysis: 

Overview:  Statistical analyses were performed using SPSS Grad Pack 25.0. Statistics was 

done with the aid of a consultant, Andrew Dennhardt, Michigan State University Center for 

Statistical Training and Consulting (CSTAT).  The level of significance for all tests was set to P = 

0.05. 

Greenhouse Data Analysis: Data normality was checked using a histogram to evaluate 

for skewness.  If normality was violated, a negative-binomial with loglink was used instead of a 

one-way ANOVA.   Omnibus tests showed that this model worked significantly outperforms a 

one-way ANOVA. The negative-binomial with loglink was used to show differences between the 

 

33 

cultivars, experiment, and Cultivar x Experiment interactions at α = 0.05.  Variables analyzed 

included population densities of SCN eggs, cysts, egg/cyst, and stained nematodes in root 

tissue.   A histogram of the Cook’s distances was visually inspected to check for outliers.  No 

outliers were detected. The raw and Pearson residuals were plotted against the predicted 

values in order to check for violation of the homogeneity of variance assumption.  If residuals 

were normally distributed then a general linear model was used for analysis.  if any treatments 

were discovered to have zero counts they were removed from the analysis due to treatments 

with all zero counts having no variability.  It was not determined if cysts recovered were from 

initial inoculation. There were no significant differences (P<0.05) between runs of different time 

periods and the data was analyzed together.  Confidence Intervals of 95% are provided where 

appropriate. 

  

Field Data Analysis:  Statistics were conducted as outlined in the greenhouse section.   

Data from 2016 and 2017 was analyzed separately since there were significant (P<0.05) 

differences between years.  Location and cultivar interactions were included when appropriate. 

If there was no significant site x cultivar interaction then data was combined over sites.  The 

negative-binomial with loglink was used to show differences between the cultivars, locations, 

and Cultivar x Location interactions at α = 0.05.  The analysis for reproductive factor (RF=Pf/Pi) 

was conducted using a Univariate General Linear Model.  RF Data was square root transformed 

to due to unequal variances.  After transformation data was in accordance to equal variance 

assumptions.  A square root transformation was chosen due to the low numbers and zeros 

present in count data.  This was done because residuals plotted appeared to normally 

 

34 

distrusted.  Reproductive factor was determined from eggs recovered.  One outlier was 

removed from Dundee RF in 2017.  

Results 

Cyst Development Under Greenhouse Conditions 

Statistical analysis showed no significant (P<0.05) interactions among cultivars and dates 

the experiments were conducted; therefore, experiments are combined for presentation.  The 

susceptible and PI 88788 resistant soybean cultivars had the highest mean population of cysts, 

with 94 and 44 per 100 cm3 respectively, and were not significantly (P<0.05) different from each 

other (Table 2).  All Brassica and Raphanus cultivars had significantly (P<0.05) fewer cysts than 

the two soybean cultivars, and did not differ significantly (P<0.05) from each other.   The mean 

number of cysts for the Brassica and Raphanus cultivars was ~1.5 per 100 cm3. 

 

 

 

 

 

 

 

 

 

 

 

35 

Table 2: SCN cysts recovered from soil of soybean, radish, and mustard cultivars under 
greenhouse conditions. 

Treatment 

Mean1 

Standard Error 

95% Confidence Interval 

(100 cm3 of soil) 

DF155® susceptible 
soybean 
DF242N® PI 88788 
soybean 
Groundhog® daikon 
radish  
Braco® white mustard  
Maximus® oilseed radish  
Image® oilseed radish  
Action® white mustard  
Biofum® Summer blend3 
Cappuchino® oilseed 
radish  
Defender® oilseed radish  

95 A2 

44 A 

2 B 

2 B 
2 B 
2 B 
1 B 
1 B 
1 B 

1 B 

17.70 

8.40 

0.77 

0.72 
0.75 
0.71 
0.46 
0.41 
0.41 

0.46 

Lower 
65.61 

Upper 
136.71 

30.39 

64.10 

1.02 

0.92 
0.85 
0.65 
0.54 
0.45 
0.45 

0.41 

4.31 

3.98 
4.10 
3.82 
2.52 
2.23 
2.23 

2.45 

1: Means from greenhouse experiments after 45 days.  
2: Means followed by same letter are not significantly different from each other. 
3: 50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba 
 

Egg Production Under Greenhouse Conditions  

No significant (P<0.05) interactions were detected between cultivars and the dates the 

experiments were conducted; therefore results are combined for presentation.  The susceptible 

and PI 88788 resistant soybeans cultivars had the highest egg density.  There were no 

significant differences (P<0.05) in egg density between the susceptible and PI 88788 soybean 

cultivars (Table 3). SCN egg densities on Brassica and Raphanus cultivars were much lower 

(P<0.05), and did not differ among cultivars (Table 3).   

 

36 

Table 3: SCN eggs recovered from soil of soybean, radish, and mustard cultivars under 
greenhouse conditions. 

Treatment 

Mean1 

Standard Error 

DF155® susceptible 
soybean 
DF242N® PI 88788 
soybean 

Braco® white mustard  

Groundhog® daikon radish  

Image® oilseed radish  

Maximus® oilseed radish  

Defender® oilseed radish  

Cappuchino® oilseed 
radish  

Biofum® Summer blend3  

Action® white mustard  

4354 A2 

1794 A 

74 B 

66 B 

60 B 

57 B 

35 B 

31 B 

29 B 

27 B 

810.8 

334.1 

23.0 

20.0 

21.2 

18.4 

11.3 

9.2 

8.6 

7.8 

95% Confidence Interval 

Lower 

Upper 

3022.5 

6271.6 

1244.9 

2584.0 

40.6 

36.0 

29.7 

29.9 

18.2 

17.6 

16.5 

15.0 

134.13 

119.16 

119.9 

107.1 

65.8 

55.6 

52.0 

47.5 

1: Means from greenhouse experiments after 45 days. 
2: Means followed by same letter are not significantly different from each other. 
3: 50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba. 
 

SCN Fecundity Under Greenhouse Conditions  

The number of eggs per cyst was highly variable among treatments (Figure 4).  The 

susceptible soybean and PI 88788 cultivars had the greatest mean number of eggs per cyst with 

50 and 48 per 100 cm3, respectively.  They were significantly (P<0.05) greater than Cappuchino 

oilseed radish and Action white mustard which had means of 23 and 19, respectively.  None of 

the Brassica and Raphanus cultivars were significantly (P<0.05) different from one another.   

 

37 

Table 4: SCN eggs per cyst recovered from soil of soybean, radish, and mustard cultivars 
under greenhouse conditions. 

Treatment 

Mean1 

(100 cm3 soil) 

Standard Error 

95% Confidence Interval 

Lower Bound  Upper Bound 

3.9 

50 A2 

49 AB 

42.5 

40.9 

21.9 
17.7 

3.9 

6.3 
6.3 

29 ABC 
26 ABC 

34 ABC 
30 ABC 

DF155® susceptible 
soybean 
DF242N® PI 88788 
soybean 
Braco® white mustard  
Groundhog® daikon 
radish  
Image® oilseed radish  
Maximus® oilseed 
radish 
Defender® oilseed 
radish  
Biofum® Summer 
blend3 
Cappuchino® oilseed 
radish  
Action® white mustard 
hood  
1: Means from greenhouse experiments after 45 days.  
2: Means followed by same letter are not significantly different from each other. 
3: 50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba. 
 

6.0 

6.0 

6.0 

7.0 
6.6 

6.6 

13.1 

11.4 

23 C 

19 C 

15.5 
12.6 

12.0 

25 ABC 

25 BC 

57.9 

56.2 

46.8 
42.5 

42.9 
38.6 

38.0 

36.9 

35.2 

31.1 

7.3 

SCN Population Densities on Root Systems in the Greenhouse 

Differences in SCN population densities were observed among the stained root systems.  

Susceptible and PI 88788 soybean cultivars did not differ significantly (P<0.05) from each other, 

and had the highest SCN densities (Figure 5).  All of the Brassica and Raphanus cultivars had 

fewer nematodes, less than 1.0 per root system (Table 5). 

 

 

 

38 

Table 5: SCN recovered from whole root systems of soybean, radish, and mustard cultivars 
under greenhouse conditions. 

Treatment 

DF155® susceptible 
soybean 
DF242N® PI 88788 
soybean 
Maximus® oilseed radish  
Groundhog® daikon 
radish  
Action® white mustard  
Image® oilseed radish  
Braco® white mustard  
Defender® oilseed radish  

Biofum® Summer blend3 

Mean1 

49.7 A2 

36.4 A 

0.7 B 
0.5 B 

0.3 B 
0.2 B 
0.1 B 
0.0 B 

0.0 B 

9.31 

6.86 

0.35 
0.25 

0.19 
0.17 
0.10 
0.00 

0.00 

Standard Error 

95% Confidence Interval 

Lower 
34.38 

Upper 
71.72 

25.20 

52.71 

0.27 
0.16 

0.11 
0.05 
0.01 
0.00 

0.00 

0.00 

1.84 
1.31 

1.03 
1.03 
0.70 
0.00 

0.00 

0.00 

0.00 B 

Cappuchino® oilseed 
radish  
1: Means from greenhouse experiments after 45 days. 
2: Means followed by same letter are not significantly different from each other 
3: 50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba. 
 

0.000 

Cyst Development Under Field Conditions 

2016 – There was no significant (P<0.05) cultivar x site interaction for cyst development.  

There were, however, significant (P<0.05) differences between sites and cultivars.  East Lansing 

and Edwardsburg had significantly (P<0.05) higher cyst densities than Dundee (Table 6).  Biofum 

Summer blend, Braco white mustard, Maximus oilseed radish, and Action white mustard all had 

cyst densities that were significantly lower than the susceptible and PI 88788 soybeans (Table 

7).  No Brassica or Raphanus cultivars were significantly (P<0.05) different from the weedy 

fallow. 

 

 

39 

Table 6: SCN cysts recovered from three field sites across Michigan in 2016. 

Field 

Mean1 

(100 cm3 soil) 

Standard Error 

95% Confidence Interval 

Edwardsburg 

East Lansing 

Dundee 

7 A 

6 A2 

2 B 

1.00 

0.89 

0.41 

Lower 
5.10 

4.40 

1.74 

Upper 
9.09 

7.93 

3.39 

1: Means of three field experiments after 90 days. 
2: Means followed by same letter are not significantly different from each other 
 

2017 - There was no significant (P<0.05) cultivar x site interaction for cyst development.  

Significant differences were observed between sites and cultivars.  All three locations were 

significantly (P<0.05) different from each other (Table 8).  Edwardsburg had the highest number 

of cysts recovered while East Lansing had the lowest.  Braco white mustard was the only 

cultivar that was significantly (P<0.05) different from all three soybeans (Table 9).  No Brassica 

or Raphanus cultivars were significantly (P<0.05) different from the weedy fallow.  

Table 7: SCN cysts recovered from soil of soybean, radish, and mustard cultivars at three field 
sites across Michigan in 2016. 

Treatment 

DF155® susceptible 
soybean 
DF242N® PI 88788 
soybean 
Image® oilseed radish  
Defender® oilseed radish  
Biofum® Summer blend3 
Braco® white mustard  
Weedy fallow 
Maximus® oilseed radish  
Action® white mustard  

Mean1 

(100 cm3 soil) 

Standard Error 

95% Confidence Interval 
Upper 

Lower 

24.5A 

16 AB2 

4 BC 
4 BC 
3 C 
3 C 
3 C 
3 C 
2 C 

5.89 

3.89 

1.05 
0.98 
0.88 
0.85 
0.83 
0.81 
0.60 

15.26 

9.90 

2.36 
2.07 
1.85 
1.75 
1.73 
1.72 
1.11 

39.21 

25.74 

6.64 
6.12 
5.46 
5.27 
5.15 
5.06 
3.58 

1: Means from three field experiments after 90 days.  
2: Means followed by same letter are not significantly different from each other. 
3:  50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba. 

 

40 

Table 8: SCN cysts recovered from three field sites across Michigan in 2017. 

Field 

Mean1 

(100 cm3 soil) 

Standard Error 

95% Confidence Interval 

Edwardsburg 
Dundee 
East Lansing 
1: Means of three field experiments after 90 days. 
2: Means followed by same letter are not significantly different from each other 
 

0.49 
0.21 
0.09 

3 A2 
1 B 
0.3 C 

Lower 
2.19 
0.66 
0.18 

Upper 
4.12 
1.52 
0.56 

Table 9: SCN cysts recovered from soil of soybean, radish, and mustard cultivars at three field 
sites across Michigan in 2017. 

Treatment 

Mean1 

(100 cm3 soil) 

Standard Error 

95% Confidence Interval 

Lower 
1.42 

0.79 

1 AB 

3 A2 

2 AB 

0.75 

0.55 

0.46 

0.49 

1 ABC 

DF242N® PI 88788 
soybean 
INA PI 437654 x PI 88788 
soybean  
Defender® oilseed radish  
DF155® susceptible 
soybean 
Groundhog® daikon radish  
Image® oilseed radish  
Weedy fallow 
TC JS001 blend3 
Braco® white mustard  
1: Means from three field experiments after 90 days. 
2: Means followed by same letter are not significantly different from each other 
3: 35% INA soybean, 35% cereal rye, 30% Maximus oilseed radish 
 

1 ABC 
0.7 BC 
0.7 BC 
0.7 BC 
0.4 C 

0.46 
0.34 
0.28 
0.28 
0.13 

0.35 
0.28 
0.30 
0.29 
0.20 

0.73 

0.67 

Upper 
4.53 

3.12 

2.67 

2.77 

1.93 
1.52 
1.61 
1.58 
1.06 

Egg Production Under Field Conditions 

2016 – There was a significant (P<0.05) cultivar x site interaction (Table 10) for egg 

production.  At East Lansing, the egg densities of the susceptible and PI 88788 soybeans were 

significantly (P<0.05) greater than all Brassica and Raphanus cultivars, with means of 4076 and 

2057, respectively.  No Brassica and Raphanus cultivars were significantly (P<0.05) different 

 

41 

from each other.  No Brassica or Raphanus cultivars were significantly (P<0.05) different from 

the weedy fallow.  At Dundee, the susceptible and PI 88788 soybeans resulted in significantly 

(P<0.07) greater egg densities than all Brassica and Raphanus cultivars, with means of 4273 and 

2073, respectively.  Image oilseed radish egg densities, with a mean of 310, were significantly 

(P<0.05) greater than Braco white mustard and Defender oilseed radish with means of 37 and 

40, respectively.  No Brassica or Raphanus cultivars were significantly (P<0.05) different from 

the weedy fallow.  At Edwardsburg the susceptible soybean was significantly (P<0.05) greater 

than all Brassica and Raphanus cultivars with a mean of 3333.  The egg densities of Action white 

mustard, with a mean of 233, were the only Brassica and Raphanus cultivar that were 

significantly (P<0.05) lower than the susceptible and PI 88788 soybeans.   

2017 – There was a significant cultivar x site interaction (Table 11) in egg production.  At 

East Lansing the PI 88788 soybean, with a mean of 67, resulted in significantly (P<0.05) greater 

egg densities than the PI 437654 x PI 88788 soybean, Image oilseed radish, Groundhog daikon 

radish, and Braco white mustard; with means of 10, 10, 7, and 3, respectively.  The weedy 

fallow also had significantly (P<0.05) greater egg densities than Groundhog daikon radish and 

Braco white mustard.  The Dundee site had low egg densities on all cultivars. There are no 

significant (P<0.05) differences between cultivars.  At Edwardsburg, the PI 88788 soybean was 

significantly (P<0.05) greater than all Brassica and Raphanus cultivars, with a mean of 1167. The 

TC JS001 blend and Braco white mustard had the lowest egg densities and were significantly 

(P<0.05) different from all three soybean cultivars.  The weedy fallow was not significantly 

(P<0.05) different from any Brassica or Raphanus cultivar.   

 

42 

Table 10: SCN eggs recovered from soil of soybean, radish, and mustard cultivars at three 
field sites across Michigan in 2016. 

Edwardsburg1 
(Standard Error) 
3333 A (1361) 

Treatment 

East Lansing1 

Dundee1 

(Standard Error) 
4076 A2 (1664) 

(Standard Error) 
4273 A (1745) 

2073 A (847) 
37 C (15.2) 

DF155® susceptible 
soybean 
DF242N® PI 88788 soybean 
Braco® white mustard  
Weedy fallow 
Defender® oilseed radish  
Biofum® Summer blend3 
Maximus® oilseed radish  
Image® oilseed radish  
Action® white mustard  
1: Means from field experiments after 90 days from 100 cm3 soil. 
2: Means followed by same letter within a column are not significantly different from each 
other 
3: 50% Brassica carinata, 40% Raphanus sativus var. oleifera, 10% Sinapis alba 

2057 A (840) 
280 B (115) 
163 B (67.9) 
140 B (57.3) 
123 B (50.5) 
120 B (49.2) 
110 B (45.1) 
110 B (45.1) 

1373 AB (561) 
300 BC (123) 
250 C (102) 
480 BC (196) 
343 BC (140) 
353 BC (144) 
325 BC (133) 
233 C (95.5) 

120 BC (49.2) 
217 BC (88.7) 
310 B (127) 
100 BC (41) 

110 BC (45.1) 

40 C (17.8) 

Table 11: SCN eggs recovered from soil of soybean, radish, and mustard cultivars at three 
field sites across Michigan in 2017. 

Treatment 

East Lansing1 

Dundee1 

(Standard Error) 

(Standard Error) 

Edwardsburg1 
(Standard Error) 
1167 A (133.6) 
553 AB (248.4) 

80 A (7.3) 

327 ABC (476.5) 

10 BC (27.4) 

13 ABC (53.2) 

17 A (32.9) 
33 A (14.8) 

67 A2 (4.3) 
17 ABC (7.3) 

DF242N® PI 88788 soybean 
DF155® susceptible 
soybean 
INA PI 437654 x PI 88788 
soybean  
Defender® oilseed radish  
Groundhog® daikon radish  
Weedy fallow 
Image® oilseed radish  
TC JS001 blend3 
Braco® white mustard  
1: Means from field experiments after 90 days from 100 cm3 soil. 
2: Means followed by same letter within a column are not significantly different from each 
other 
3: 35% INA soybean, 35% cereal rye, 30% Maximus oilseed radish 
 

53 A (22) 
30 A (12.5) 
23 A (9.7) 
30 A (12.5) 
40 A (17.8) 
20 A (8.4) 

130 BCD (53.3) 
107 BCD (44) 
80 CD (32.9) 
73 CD (30.1) 
38 D (16.9) 
33 D (13.8) 

43 AB (17.9) 
10 BC (4.3) 
13 ABC (5.8) 

3 C (1.6) 

7 C (2.9) 

 

 

43 

Fecundity Under Field Conditions 

2016- There was no significant (P<0.05) cultivar x site interaction for eggs per cyst.  

There were significant (P<0.05) differences among cultivars, as well as the sites.  Dundee had 

the greatest eggs per cyst with a mean of 72 (Table 12).  This was significantly (P<0.05) greater 

than at East Lansing, which had a mean of 43 eggs per cyst.  Susceptible soybean had 

significantly (P<0.05) higher eggs per cyst than all Brassica and Raphanus cultivars, with a mean 

of 133 (Table 13).  With Biofum summer blend, Braco white mustard, and Defender white 

mustard, the number of eggs per cyst were all significantly (P<0.05) lower than the susceptible 

and PI 88788 soybeans.  None of the Brassica and Raphanus cultivars were significantly 

(P<0.05) different than the weedy fallow.  Groundhog daikon radish, with a mean eggs per cyst 

of 8, was the only Brassica and Raphanus cultivar that was significantly different from the three 

soybeans.  No cultivars were significantly (P<0.05) different from the weedy fallow.   

Table 12: SCN cysts recovered from soil of soybean, radish, and mustard cultivars at three 
field sites across Michigan in 2017. 

Field 

Mean1 
(100 cm3 

Standard 

Error 

95% Confidence Interval 

Lower 

Upper 

Dundee 
Edwardsburg 

East Lansing 

soil) 
72A2 
58AB 

43B 

9.8 
7.9 

5.9 

54.8 
44.2 

32.7 

93.9 
75.8 

56.2 

1: Means of three field experiments after 90 days. 
2: Means followed by same letter are not significantly different from each other 
 

 

 

 

 

44 

Table 13: SCN eggs per cyst recovered from soil of soybean, radish, and mustard cultivars at 
three field sites across Michigan in 2016. 

Treatment/Cultivars 

Mean1 

(100 cm3 soil) 

Standard Error 

95% Confidence Interval 

DF155® susceptible 
soybean 
DF242N® PI 88788 
soybean 
Maximus® oilseed radish  
Action® white mustard  

Image® oilseed radish  
Biofum® Summer blend3 

Braco® white mustard  

Weedy fallow 
Defender® oilseed radish  

134 A2 

31.608 

Lower 
83.99 

Upper 
212.38 

100 AB 

23.432 

62.14 

157.33 

62 BC 
52 BC 

50 BC 
43 C 

42 C 

41 C 
37 C 

14.643 
12.344 

11.79 
10.347 

10.018 

9.658 
8.794 

38.66 
32.5 

31.02 
27.19 

26.28 

25.35 
23.04 

98.16 
82.67 

78.94 
69.24 

67 

64.61 
58.78 

1: Means from three field experiments after 90 days.  
2: Means followed by same letter are not significantly different from each other. 
3:  50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba. 
 

2017 – There was a significant cultivar x site interaction (Table 14) for eggs per cyst.  At 

Dundee and Edwardsburg there were no significant (P<0.05) differences between treatments.  

At East Lansing, PI 88788 soybean had the greatest eggs per cyst with a mean of 67.  

Groundhog daikon radish, defender oilseed radish, and Braco white mustard, with mean eggs 

per cyst of 7, 4, and 3 respectively, were significantly (P<0.05) different from both the PI 88788 

soybean and the weedy fallow.  No Brassica and Raphanus cultivars were significantly (P<0.05) 

different from each other or the susceptible and PI 437654 x PI 88788 soybeans.   

 

 

 

45 

Table 14: SCN eggs per cyst recovered from soil of soybean, radish, and mustard cultivars at 
three field sites across Michigan in 2017. 

Treatment 

DF242N® PI 88788 soybean 
Weedy fallow 
DF155® susceptible 
soybean 
TC JS001 blend3 
INA PI 437654 x PI 88788 
soybean  
Image® oilseed radish  
Groundhog® daikon radish  

East Lansing1 

Dundee1 

Edwardsburg1 

(Standard Error) 

(Standard. Error) 

(Standard. Error) 

67 A2 (27.4) 
43 AB (19.3) 
17 ABC (7.0) 

13 ABC (5.6) 
10 BC (4.3) 

10 BC (4.3) 

7 C (2.9) 

5 A (2.4) 
20 A (8.8) 
17 A (7.2) 

21 A (8.7) 
18 A (7.3) 

25 A (10.4) 

8 A (3.4) 

48 A (19.6) 
24 A (10) 
54 A (22.1) 

17 A (7.1) 
53 A (21.7) 

40 A (16.5) 
25 A (10.4) 

Defender® oilseed radish  

4 C (17.9) 

8 A (8.4) 

12 A (12.5) 

3 C (1.6) 

20 A (8.4) 

Braco® white mustard  
1: Means from field experiments after 90 days from 100 cm3 soil.  
2: Means followed by same letter within a column are not significantly different from each 
other 
3: 35% INA soybean, 35% cereal rye, 30% Maximus oilseed radish 
 

19 A (7.9) 

Reproductive Factor in Field Conditions 

2016 – There were significant (P<0.05) cultivar x site interactions (Table 15) for RF.  At 

East Lansing, both the susceptible and PI 88788 soybeans had a significantly (P<0.05) greater RF 

than all the Brassica and Raphanus cultivars tested.  None of the Brassica and Raphanus 

cultivars were significantly (P<0.05) different from the weedy fallow.  At Dundee, only the 

susceptible soybean was significantly (P<0.05) greater than the Brassica and Raphanus 

cultivars.  None of the Brassica and Raphanus cultivars were significantly (P<0.05) different 

from the weedy fallow.  At Edwardsburg there were no significant (P<0.05) differences among 

treatments.   

 

 

46 

Table 15: Impact of soybean, radish, and mustard cultivars on Heterodera glycines 
reproductive factor under 2016 field conditions. 

Treatment 

East Lansing1 

(Standard Error) 

Dundee1 

(Standard Error) 
105.2 A (127.2) 

Edwardsburg1 
(Standard Error) 

3.5 A (4.4) 

48.8 A (56.1) 

29.2 AB (37.9) 

40.4 A2 (37.3) 

DF155® susceptible 
soybean 
DF242N® PI 88788 soybean 
Braco® white mustard  
Weedy fallow 
Defender® oilseed radish  
Biofum® Summer blend3 
Maximus® oilseed radish  
Image® oilseed radish  
Action® white mustard  
1: Means from field experiments after 90 days from 100 cm3 soil. 
2: Means followed by same letter within a column are not significantly different from each 
other. Pairwise analysis from square root transformation. 
3: 50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba. 
 

2.2 A (3.4) 
1.2 A (2.2) 
7.2 A (15.7) 
5.4 A (8.6) 
0.4 A (0.3) 
1.37 A (1.7) 
1.1 A (1.3) 
6.5 A (14.5) 

3.6 B (4.2) 
5.7 B (10.0) 
1.4 B (1.6) 
3.4 B (2.5) 
5.3 B (7.3) 
2.7 B (1.8) 
2.5 B (3.0) 

0.4 B (0.3) 
1.0 B (1.0) 
1.4 B (2.4) 
1.3 B (1.1) 
4.9 B (5.5) 
2.3 B (1.7) 
3.3 B (7.2) 

2017 – There was no significant (P<0.05) cultivar x site interaction.  There were, 

however, significant (P<0.05) differences among locations of (Table 16).  Edwardsburg had a 

significantly (P<0.05) greater RF than Dundee and Last Lansing.  There were no significant 

(P<0.05) differences among experimental cultivars (Table 17).   

Table 16: Impact of 2017 sites on Heterodera glycines on reproductive factor. 

Field 

Mean1 

(100 cm3 soil) 

Standard Error 

95% Wald Confidence Interval 

Edwardsburg 
Dundee 
Collins 
1: Means from field experiments after 90 days.  
2: Means followed by same letter are not significantly different from each other 
 

4.1 A2 
1.2 B 
0.6 B 

7.9 
2.0  
1.5 

Lower 
-0.63 
-0.08 
2.86 

Upper 
1.91 
2.49 
5.39 

 

 

 

 

47 

Table 17: Impact of soybean, radish, and mustard cultivars on Heterodera glycines 
reproductive factor under 2017 field conditions. 

Treatment 

East Lansing1 

Dundee1 

Edwardsburg1 

(Standard Error) 

(Standard Error) 

(Standard. Error) 

1.54 A (3.19) 
1.67 A (2.07) 

0.27 A (0.41 

1.16 A (2.15) 

8.57 A (10.01) 

0.27 A2 (0.41) 
0.71 A (.78) 

10.5 A (16.43) 
6.07 A (6.57) 

DF242N® PI 88788 soybean 
DF155® susceptible 
soybean 
INA PI 437654 x PI 88788 
soybean  
Defender® oilseed radish  
Groundhog® daikon radish  
Weedy fallow 
Image® oilseed radish  
TC JS001 blend3 
Braco® white mustard  
1: Means from field experiments after 90 days from 100 cm3 soil. 
2: Means followed by same letter within a column are not significantly different from each 
other.  Pairwise analysis from square root transformation.  
3: 35% INA soybean, 35% cereal rye, 30% Maximus oilseed radish 
 

1.95 A (3.18) 
0.567 A (1.20) 
1.02 A (1.25) 
1.06 A (1.04) 
1.57 A (2.61) 
0.28 A (0.38) 

0.94 A (1.34) 
5.26 A (10.35) 
1.91 A (2.10) 
1.16 A (1.44) 
1.7 A (2.04) 
1 A (1.10) 

0.67 A (0.82) 
0.33 A (0.52) 
2.27 A (4.35) 

0.5 A (.84) 

0.67 A (0.82) 
0.17 A (0.41) 

 

 

 

 

 

 

 

 

 

48 

Discussion and Conclusion 

Discussion 

The impacts of Brassica and Raphanus taxa tested on SCN were similar in all greenhouse 

experiments.   Across sites, as well as years, results were more variable.   A single SCN 

population and plant growth medium was used for all greenhouse experiments. This, however, 

was not true for the field experiments.  The variability in the field appears to be associated with 

fundamental differences in the SCN populations, as well as the biological, chemical, physical 

and environmental attributes of the sites.  Variability between years was likely caused by a 

variety of factors, site changes and weather conditions being two.  The populations recovered 

in 2017 were much lower than those of 2016.  In 2017 conditions were dry for the first 45 days 

of growth and waterlogged for the last 45 days.  These conditions were not conducive to plant 

growth. These are also not the optimal conditions for SCN (Davis and Tylka, 2000).  The results 

indicate that while greenhouse research can provide a basic understanding of host-parasite 

relationships, it does not represent field conditions.  Site-specific research, therefore, is 

essential for developing accurate predictions and recommendations about the impacts of 

Raphanus and Brassica cultivars on SCN. 

There is no evidence that any of the cultivars tested acted as a trap crop for SCN.   One 

experiment evaluating mustard and radish trap crops for Beet Cyst Nematode resulted in very 

low reproductive factors on the cultivars evaluated (Smith et al., 2004).  In contrast, the 

reproductive factors of this experiment were much higher than these examples of trap crops.  A 

similar experiment that also contained a fallow control returned similarly small RF’s even while 

 

49 

the fallow increased numbers (Wright et al., 2018).  The RF’s of the cultivars evaluated in this 

experiment were also higher when compared to the Beet Cyst Nematode trap crops.   

There are many known weeds host of SCN (Poromart et al., 2015: Venkatesh et al, 

2000).  Several of these are winter annuals that are present in Michigan.  While no weed 

identifications were made in the fallow plots, it is possible that one or more alternate hosts 

were present at the sites.  By comparing the fallow plots of this experiment to the number of 

eggs recovered from past experiments on weed hosts, similarities can be observed (Poromart et 

al., 2015: Venkatesh et al, 2000).  

It has been observed that SCN’s ability to reproduce on PI 88788 resistant soybean 

cultivars is increasing (McCarville et al., 2017).  These aggressive populations are present in 

Michigan due to the overuse of the PI 88788 resistance source. The main reason PI 88788 

cultivars were used was to observe how many eggs were produced versus a susceptible 

soybean.  Data from the MSU studies confirm this trend.  The soybean cultivars in both the 

greenhouse and field experiments had the highest cyst and egg population densities, compared 

to the Raphanus and Brassica cultivars.  In all experiments, the susceptible soybean and PI 

88788 soybean cultivars were not significantly different from each other.  In the greenhouse, as 

well as the 2016 field experiments, susceptible soybean cultivars had circa 50% more egg 

production, compared to the PI 88788 soybean cultivars.   In the 2017 field experiments, the PI 

88788 soybean had greater egg production than the susceptible soybean at Edwardsburg and 

East Lansing, Mi.  At Edwardsburg, in particular, PI 88788 eggs were more than 2-fold greater 

than the susceptible soybean cultivar.  The mean number of eggs per cyst was very similar 

between PI 88788 and susceptible soybeans in the greenhouse experiments.  This was also true 

 

50 

at the field sites. In 2017 at Edwardsburg, however, the PI 88788 soybean resulted in a greater 

number of eggs per cyst than the susceptible soybean.  In 2017, INA (PI 437654 x PI 88788) was 

included in the research.  The number of eggs recovered was variable among locations.  In East 

Lansing and Edwardsburg, INA (PI 437654 x PI 88788) soybean had lower egg production than 

the susceptible and PI 88788 soybeans.  At Dundee, however, INA (PI 437654 x PI 88788) 

resulted in more eggs than susceptible and PI 88788 soybeans.  Despite this, it was never 

significantly (P<0.05) different from the susceptible soybean. It was significantly (P<0.05) 

different from the PI 88788 soybean at East Lansing for cysts, eggs, and eggs per cyst recovered, 

but not at the other locations.  This indicates an increasing virulence of certain HG Types, as 

previously described by McCarville et al. (2017).   

There were no statistically significant differences among Raphanus and Brassica 

cultivars in the greenhouse experiments.  In the field, however, there was some variability. All 

of them resulted in lower SCN cysts, eggs, eggs per cyst, and RF than the soybean cultivars.  

Image oilseed radish at Dundee in 2016 resulted in greater egg densities than Braco white 

mustard and Defender oilseed radish.  Image oilseed radish at East Lansing in 2016 had the 

lowest egg production of the Brassica and Raphanus cultivars while Braco had the greatest.  

Braco at East Lansing in 2016 had the greatest egg densities of the Brassica and Raphanus 

cultivars while at Dundee that same year it had the lowest egg densities. In both years, 

Defender oilseed radish had some of the highest SCN cysts and eggs recovered after 90 days, 

except at Dundee in 2016.  In 2017 TC JS001 and Braco white mustard resulted in some of the 

fewest eggs and cysts recovered.  When it comes to cover cropping with Brassica and 

Raphanus, the 2016 and 2017 field experiments indicate that there are many variables that 

 

51 

determine the overall impact of the site on SCN populations.  Variability in soil parameters, 

such as composition, permeability, and microbiome, are likely important factors.  It may be that 

SCN populations interact differently with Brassica and Raphanus cover crop, similar to the 

differences between HG types. 

Root staining was used to determine how many individuals infected root tissue.  Once 

again, the two soybean cultivars were not statistically different from each other and high 

numbers of SCN were observed in root tissue.  Furthermore, very few individuals were 

observed in the Raphanus and Brassica cultivars.  No SCN were detected in roots of Defender 

oilseed radish, Biofum Summer blend, and Cappuchino oilseed radish.  This is additional 

evidence that these Brassica and Raphanus cultivars are not hosts for SCN.  Root staining 

analysis is a time-consuming process; however, it is the best method of examination.  This is 

because there are fewer steps in the processing procedure from the field to the microscope, 

and therefore less opportunities for cysts and eggs to be lost.    

The SCN reproductive factor (RF) was variable among experimental cultivars.  At East 

Lansing and Edwardsburg in 2016, all Brassica and Raphanus cultivars had lower RFs than the 

weedy fallow.  At Dundee and East Lansing, all Brassica and Raphanus cultivar RFs were much 

lower than the susceptible and PI 88788 soybeans.  At Dundee in 2016 only Braco white 

mustard had a lower RF than the weedy fallow.  It was the only Brassica and Raphanus cultivar 

at that location to decrease populations of SCN.  Meanwhile, at East Lansing, Braco white 

mustard had the second greatest RF of the Brassica and Raphanus cultivars. The East Lansing 

and Edwardsburg weedy fallow plots had high RF values, with SCN experiencing on average a 5-

fold or greater populations increase.  This indicates that there were probably alternate hosts at 

 

52 

these locations among the weeds, probably of the Caryophyllacaea family which is known to 

support SCN populations (Venkatesh, 2000). This could explain some of the high Brassica and 

Raphanus RF’s, especially at Edwardsburg where all experimental cultivars resulted in 

reproduction. At Edwardsburg, both soybean cultivars had RF values that were lower than the 

weedy fallow.  At this location Action white mustard was the only Brassica and Raphanus 

cultivar that had a greater RF than the soybean cultivars.  Defender oilseed radish at Dundee 

and East Lansing had some of the lowest RFs of the Brassica and Raphanus cultivars, as well as 

being close to or below the weedy fallow.  At Edwardsburg it had the second highest RF of the 

Brassica and Raphanus cultivars, but was still below the weedy fallow. Maximus oilseed radish 

at East Lansing and Dundee had RF’s that were similar to the weedy fallow, indicating it is 

possibly a poor host for SCN.  Overall host status appears to be site dependent.  

RF values were lower in 2017, compared to 2016.  At East Lansing, all cultivars tested 

had lower RFs than the weedy fallow and resulted in decreased populations.  Braco white 

mustard and PI 88788 soybean had the lowest RFs, respectively.  At Dundee, Groundhog daikon 

radish and Braco white mustard had RFs below that of the weedy fallow.  At Edwardsburg, 

however, Groundhog Daikon radish was the only Brassica or Raphanus cultivar with a RF above 

the weed fallow. The TC JS001 blend, Braco white mustard, and Defender oilseed radish often.   

They may be poor hosts, allowing some reproduction.  Image oilseed radish had a low RF at all 

three locations. They are most likely non-hosts; however, they may result in premature 

emergence as a way to explain to population decreases observed.   

 

 

53 

The results of the field experiments indicate a distinct need for a Cover Crop Evaluation 

Test to determine which cultivars are appropriate for specific SCN-infested sites.  This should be 

similar to HG Type testing (Niblack et al., 2002).  Its primary purpose is to assure that specific 

cultivars are non-hosts for specific SCN field populations.  This concept has not previously been 

proposed for cover crops in regards to nematode management or their general usage.  It may 

explain a significant portion of the variability of cover crop use success.  A greenhouse or field 

Cover Crop Type Test for SCN management should consist of the following seven components:  

1) a susceptible soybean cultivar, 2) PI 88788 resistant soybean cultivar, 3) clean fallow, 4) 

daikon radish cultivar, 5) oilseed radish cultivar, 6) a white mustard cultivar and 7) a widely 

used non-host Graminacaeae cultivar such as Wheeler Rye.  The greenhouse growing media 

should be SCN-infested soil from the specific field site of interest.  After 90 days, the soil should 

be processed for SCN cysts, eggs, and eggs per cysts population densities.  The field Type Test 

should be conducted during an appropriate window for cover crop planting.  If possible, root 

staining should also be conducted, or possibly substituted for the soil sample depending on 

available time and labor.   

The data recovered from the susceptible soybean cultivars and PI 88788 cultivars 

confirm the most recent HG Type Tests for each field location used in this research.  There is 

also potential that the dual PI 437654 x PI 88788 resistance cultivars may have potential as a 

Category 2 Trap Crops, as indicated from the results of INA (PI 437654 x PI 88788) soybean 

cultivar, as well as the TCJS001 blend.  It is recommended that this be evaluated in future SCN 

research. However, as the PI 88788 source of resistance becomes increasingly compromised, it 

may be best to switch to a pure PI 437654 cultivar. 

 

54 

Conclusion 

The results show that while greenhouse experiments can provide insight into organismal 

interactions.  While there was more variability observed in the field, cover crop cultivars did not 

behave differently from the greenhouse experiments.  Further experimentation is necessary to 

determine if the site or populations cause this variability.  The field locations demonstrated that 

SCN populations present at those sites are highly aggressive on PI 88788 resistant soybean 

cultivars, with higher reproduction observed than what has been reported in past studies.  The 

PI 437654 x PI 88788 most often had the lowest densities of the soybeans in all parameters, 

however it was not always significantly different from the other two soybean cultivars. 

Additionally, at Dundee it had the highest eggs counts and at Edwardsburg had the greatest 

eggs per cyst.  Oilseed radish and white mustard cultivars appear to be safe for use as cover 

crops in SCN infested soybean fields. While they resulted in less SCN than the soybean cultivars, 

their effects on SCN were still variable among locations.  In the future, a simple SCN cover crop 

test may aid in the selection of cultivars.  The results also indicate that HG types may differ in 

the way they interact with cover crops.  If this is the case then it is necessary to conduct testing 

that is both field and cultivars specific before selecting cover crops.    

While a promising trap crop was not found from this research, the studies provide 

important information to soybean growers.  All Brassica and Raphanus cultivars evaluated 

resulted in fewer eggs than what was recovered from the soybeans cultivars. This indicates that 

the cover crop cultivars and blends are safe for use in soybean production in order to provide 

other ecosystem services.   Oilseed and daikon radishes can be used for weeds suppression and 

to reduce soil compaction (Curran et al., 2006: Clark, 2015).  Mustards can be used for 

 

55 

biofumigation (Fourie et al., 2015).  The TCJS001 blend is designed to provide several benefits.  

The Wheeler Rye is to provide biomass and build soil organic matter, the oilseed radish is to 

break up hardpan, and the PI 437654 resistant soybean will reduce nematode confirmation, 

although further testing is needed to confirm this. If found to reduce SCN populations, this 

blend could be interseeded with corn, opening a window for use in corn-soybean rotations.   

 

 

 

56 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

APPENDICES 

 

57 

APPENDIX A. Results from preliminary greenhouse trials. 

 These experiments were not considered successes but were used to refine methods for future 

experiments.  The methods were the same as described in the thesis with two exceptions.  

Cultivars were run for 30 days instead of 45 days and root staining did not occur. 

Table 18: Results of preliminary greenhouse experiments. 

Treatment 

Mean1 Cysts 

Mean1 
Eggs 

Mean1 
Eggs per 

2.00 
1.18 
0.29 
1.45 
0.00 
0.33 
2.83 
0.83 
0.63 
2.00 

Action® white mustard 
Biofum® summer blend 
Braco® white mustard 
Cappuchino® oilseed radish 
Defender® oilseed radish 
Frostmaster® winter pea 
Groundhog® daikon radish 
Maximus® oilseed radish 
DF242N® PI 88788 soybean 
DF5242R2Y® susceptible 
soybean 
Terranova® oilseed radish 
1: Based on two greenhouse experiments after 30 days.  
2: 50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba. 
 

40.00 
65.45 
45.71 
116.36 
22.22 
33.33 
153.33 
63.33 
32.50 
243.75 

Cyst 
10.00 
24.55 
40.00 
33.82 
22.22 
33.33 
40.00 
36.67 
26.88 
86.25 

0.00 

20.00 

20.00 

N 

3 
11 
7 
11 
9 
6 
6 
6 
16 
16 

6 

 

 

 

 

 

 

 

 

 

58 

APPENDIX B. Results from 2015 preliminary East Lansing field trial.   

Planting: The field location for the 2015 summer trial was at the MSU Department of 

Entomology Research Farm in East Lansing (East Lansing, Mi. 42°41'25.8"N 84°29'53.0"W).  Plot 

size was 1.8m x 3.7m.  Each plot contained six rows of plants.  Each treatment (cultivar) was 

replicated six times in a randomized complete block design.  The blocks were separated by 

seventeen feet while there was three feet between plots within the same block.  Seven Brassica 

and Raphanus cultivars were planted in addition to SCN resistant and SCN susceptible soybean 

controls. Planting of cover crops and soybeans occurred on August 18th. Nematode populations 

were determined using the methods outlines in the thesis. 

Table 19: Results from the 2015 preliminary field trial at East Lansing, MI. 

Treatment 

Biofum® summer blend 

Braco® white mustard 
Cappuchino® oilseed radish 
Defender® oilseed radish 
Frostmaster® winter pea 
Groundhog® daikon radish 
INA® PI 437654 x PI 88788 

DF5242R2Y® susceptible 
soybean 
Terranova® oilseed radish 

Mean1 
Cysts 
0.83 

0.33 

1.17 

0.83 

1.17 

1.83 

0.50 

1.83 

1.50 

Mean1 
Eggs 
33.33 

13.33 

53.33 

30.00 

43.33 

40.00 

36.67 

110.00 

Mean1 

Eggs/cyst 

26.67 

13.33 

38.33 

25.00 

25.50 

19.17 

14.50 

39.50 

103.67 

33.33 

Mean1 

N 

RF 
0.1 

0.02 

0.08 

0.1 

1.17 

0.15 

0.09 

0.26 

0.2 

6 

6 

6 

6 

6 

6 

6 

6 

6 

1: Based on six field experiments after 90 days. 
2: 50% Brassica carinata, 40% Raphanus sativus var. oleiferac, 10% Sinapis alba. 
 

 

 

 

59 

APPENDIX C. Record of deposition of voucher specimens. 

The specimens listed below have been deposited in the named museum as samples of those 

species or other taxa, which were used in this research. Voucher specimens were submitted as 

photographs.   

 

Voucher Number: 2018-08 

 

Author and Title of thesis: Jeffrey J. Shoemaker, IMPACT OF RAPHANUS AND BRASSICA 

CULTIVARS ON HETERODERA GLYCINES (Nematoda) POPULATION DEVELOPMENT 

Museum(s) where deposited: Albert J. Cook Arthropod Research Collection, Michigan State 

University (MSU) 

Specimens: Heterodera glycines  

Table 20: Voucher Specimens. 

Family 
Heteroderidae 
Heteroderidae 

Genus/Species 
Heterodera glycines 
Heterodera glycines 

Life Stage 
Juvenile 
Adult 
 

Quantity 

Preservation 

3  Photograph 
2  Photograph 

 

 

 

 

 

60 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LITERATURE CITED 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

61 

 

 

 
 

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