Plant pathogenic nematodes are major problems in crop production, causing different type of diseases. In these slides, I present my recent findings on plant nematodes in Tennessee and some Kentucky Counties.

1. Population densities and distributions
of plant parasitic nematodes in
Tennessee and Kentucky field crops.
ADVISORS:
HEATHER KELLY
ZACH HANSEN
RUFUS AKINRINLOLA
Research Specialist (Doctoral candidate)
UNIVERSITY OF TENNESSEE-KNOXVILLE

2.  A global threat to crop, food, and money.
 Annual crop damage;
 $8 Billion – USA
 ~ $80 Billion – Worldwide
 Up to 4,100 spp identified
 Destructive mouthpart (stylet)
 Wide host range;
 Agronomic and ornamental plants, and forest trees.
NEMATODES ARE COSTLY PARASITES
Handoo,1998
Figure 1. Nematode head with pointed stylet. Retrieved
online on January 30, 2019, from
https://nematode.unl.edu/thoco1.jpg

3.  Signs and Symptoms
 Root knots or galls
 Root lesions
 Excessive root branching
 Injured and stunted root
 Chlorosis
 Stunted growth
 Wilting
 Yield loss
IMPACTS TO CROP PLANTS
Handoo,1998; Jones et al. 2013.

4. MOST DAMAGING NEMATODES
1. Cyst (Heterodera and Globodera spp.)
2. Root knot (Meloidogyne spp.)
3. Root lesion (Pratylenchus spp.)
Jones et al. 2013.
1 2 3

5. MANAGING NEMATODES
 Resistance
 Rotation
 Late planting
 Early maturity group
 Seed treatment
2. Manage the fields/ nematodes
 Chemical/ nematicides
 Biological control
 Cultural practices
 Requires Integrated Pest Management (IPM)
1. Protect the crop
Handoo,1998; Jones et al. 2013.
 The goal is to reduce nematode population and dissemination

6. PREVIOUS STUDIES IN TENNESSEE
Bernard, 1980.
SCN
5%
Root-knot
21%
Lesion
nematode
22%
Stunt
21%
Spiral
31%
Percentage of samples infested
 Number of samples: 234
Study from
over 30
years ago!

7. STUDY - OBJECTIVES
1. To determine the population densities of plant
parasitic nematodes in row crop fields in
Tennessee
2. To determine the distributions of the nematodes in
Tennessee

8. SAMPLING METHOD
 County agents
 Consultants
 Farmers
 Row crop fields
 Corn
 Cotton
 Soybean
 1 inch Diameter probe
 8-10 inches deep
 20 cores/acre
 J2 and eggs extracted and
counted
 Decanting method

9.  Infestation: 162 of 169 samples
 None of the Counties sampled was nematode-free.
 Soybean cyst nematode (SCN) is most prevalent.
 Lesion nematode was next to SCN in proportion.
 Root knot occurred at a low proportion but in a high density.
 All the three nematodes were present in TN samples.
 Only SCN and lesion nematodes were found in KY.
RESULT PREVIEW

10. PROPORTION AND POPULATION
DENSITIES OF SCN AND LESION
NEMATODES
SCN No SCN
40 %
Egg/J2 per 100 cc of soil
Max (Average) Action threshold
4,569 (860) 2000+
Lesion Non Lesion
25 %
No lesion
62 (15) 20+

11. Akinrinlola et al. Unpublished data
J2 per 100 cc of soil
Max (Average) Action threshold
446 (187) 10+
Root Knot No root knot
4%
PROPORTION AND POPULATION
DENSITY OF ROOT KNOT NEMATODE

12. SCN POPULATION DISTRIBUTION
 78 % of counties is infested
with SCN.
 18 out of 23 Counties
Infested
Non-infested
Map of Tennessee and Kentucky, showing sampling area. Counties infested with SCN are
painted orange color. Blue is non-infested. Recreated by Rufus Akinrinlola, January 31, 2018,
from the website: ttp://www.herbarium.unc.edu/atlasmaps/USA-Can-clickable.html
Akinrinlola et al. Unpublished data
KY
TN

13. Infested
Top 3 Counties for SCN
County
Sample
(%)
Egg/100 cc soil
Max (Ave)
Henry 54 *4,038 (1,353)
Shelby 52 *2,291 (572)
Gibson 28 618 (473)
Non-infested
Henry
Shelby
Gibson
* Value can cause yield loss
1
3
2
Akinrinlola et al. Unpublished data
Map of Tennessee and Kentucky, showing sampling area. Counties infested with SCN are
painted orange color. Blue is non-infested. Recreated by Rufus Akinrinlola, January 31, 2018,
from the website: ttp://www.herbarium.unc.edu/atlasmaps/USA-Can-clickable.html
SCN POPULATION DISTRIBUTION

14.  57% of counties is
infested with lesion.
 13 out of 23 Counties
Infested
Non-infested
Map of Tennessee and Kentucky, showing sampling area. Counties infested with lesion
nematode are painted green. Blue is non-infested. Recreated by Rufus Akinrinlola, January
31, 2018, from the website: ttp://www.herbarium.unc.edu/atlasmaps/USA-Can-clickable.html
Akinrinlola et al. Unpublished data
LESION NEMATODE
POPULATION DISTRIBUTION

15. Infested
Non-infested
Shelby
Gibson
Dyer
Top 3 Counties for lesion
County
Sample
(%)
J2/100 cc soil
Max (Ave)
Dyer 42 *38 (16)
Shelby 24 *23 (12)
Gibson 23 *31 (16)
Map of Tennessee and Kentucky, showing sampling area. Counties infested with
lesion nematode are painted green. Blue is non-infested. Recreated by Rufus
Akinrinlola, January 31, 2018, from the website:
ttp://www.herbarium.unc.edu/atlasmaps/USA-Can-clickable.html
* This value can cause damage
Akinrinlola et al. Unpublished data
LESION NEMATODE
POPULATION DISTRIBUTION
1
2
3

16.  22% of the Counties
were infested with root
knot
 5 out of 23 Counties
Infested
Non-infested
Map of Tennessee and Kentucky, showing nematode sampling area. Counties
infested with root knot nematode are painted purple. Blue is non-infested.
Recreated by Rufus Akinrinlola, January 31, 2018, from the website:
ttp://www.herbarium.unc.edu/atlasmaps/USA-Can-clickable.html
Akinrinlola et al. Unpublished data
ROOT KNOT NEMATODE
POPULATION DISTRIBUTION

17. Infested
Non-infested
* extremely high value
Shelby Hardin
Top 2 Counties for root knot
County
Sample
(%)
J2/100 cc soil
Max (Ave)
Hardin 100 *446 (388)
Shelby 29 *261 (231)
Map of Tennessee and Kentucky, showing nematode sampling area. Counties infested with
root knot nematode are painted purple. Blue is non-infested. Recreated by Rufus Akinrinlola,
January 31, 2018, from the website: ttp://www.herbarium.unc.edu/atlasmaps/USA-Can-clickable.html
Akinrinlola et al. Unpublished data
ROOT KNOT NEMATODE
POPULATION DISTRIBUTION
1
2

18. NEMATODE DISTRIBUTION SUMMARY
100 100
60
100
0 00 0 0
GRAVES HICKMAN LOGAN
%ofsamples
infested
SCN Lesion
28
54 52
23
17
24
0 0 10
GIBSON HENRY SHELBY
%ofsamples
infested
SCN Lesion R. knot
Most infested TN counties Most infested KY counties
% of TN Counties infested % of KY Counties infested
Akinrinlola et al. Unpublished data
SCN
45%
Lesion
38%
R. knot
17%
SCN
71%
Lesion
29%

19. CONCLUSIONS
 Many fields in TN and KY are infested with SCN and Lesion nematodes.
 Root knot is also present, but it probably not common in KY.
 Population densities must be addressed in both states.
 Provide further insights on factors contributing to population increases.
 Identify the HG Types within the sampled SCN populations.

20. ACKNOWLEDGEMENTS
Heather Kelly
Zach Hansen
Rachel Guyer
HYK Lab Team
Arkansas Nematode Diagnostic Lab

21. THANK YOU!
Real . Life. SolutionReal . Life. Solution