nematodes diseases

1. Disease causing nematodes
and its effect on plants
Karthick.s
1 st M.Sc.,
CAS in botany
Madras University
Guindy campus
Chennai

2. CONTENT
 Objective
 Introduction
 What is nematode?
 Is it harmful to plant?
 What are all nematode diseases ?
 What is Rhadopholus similus ?
 Morphology
 Lifecycle
 Symptoms
 Control measures

3. OBJECTIVE
• To learn about nematodes
• To learn its characters, role on plants
• Understand disease causing nematodes
and its affect on plants.

4. Introduction
• Nematoda = nematos, meaning thread,
eidos, meaning form/like
• The Phylum Nematoda consists of the species
commonly known as roundworms.
• There are approximately 12,000 described
species, but the actual number could be many
times higher.

5. What are they?

6. Nematodes vs Annelids
Both are invertebrates with elongated bodies.
Nematodes
• Round worm.
• Largest 5 cm(small).
• Tapered at both ends.
• Majority is parasitic.
• Pseudocoelom
Annelids
• Segmented worms
• Macroscopic.
• Without tapered at end.
• Not harmful.
• True coelom.

9. What is nematode?

10. Nematodes
• are "roundworms“& microscopic in size,

11. • are triploblastic (they have an ectoderm,
mesoderm and endoderm).

12. Pseudo – false, coelom - cavity
• have a pseudocoelom (a closed fluid-
containing cavity that acts as a hydrostatic
skeleton to maintain body shape, circulate
nutrients, and hold the major organs).

13. • have a thick cuticle covering their body to
protect them from digestion.

15. Is it harmful to plant?
yes
 it punctures the cell wall
 inject saliva(contains enzyme) & take all
nutrition.
 move within body tissues .
No
 it is an important nutrition mineralizer ,
when nematodes consume bacteria and fungi
they release excess ammonium (NH4).

16. What are all nematode diseases?

17. Burrowing disease

18. OVERVIEW
Disease : Burrowing disease / Spreading
decline
Pathogen : Radopholus similis
Host : Banana and citrus
Part : root /comb

19. What is Radopholus similis ?
• Radopholus similis is considered to be the most
destructive nematode associated with banana production
worldwide. it is a pest of many agricultural crops
• It is an especially important pest of bananas and citrus.
• More than 50% of nematodes decrease the productive life
of banana fields.
• known commonly as the burrowing nematode.
• It is a migratory endoparasite of roots,
causing lesions that form cankers.
• Infected plants experience malnutrition.

20. Kingdom : Animalia
Phylum : Nematoda
Class : Secernentea
Subclass : Diplogasteria
Order : Tylenchida
Family : Pratylenchidae
Genus : Radopholus
Species : similis

21. Morphology
Body - 0.5-0.9 mm in length
Lip - rounded in female, knob like in male.
Stylet - short and stout in females, slender and
rudimentary in males.
Oesophagous - forming a lobe , dorsally overlaps to
intestine.
Vulva - located at middle of the body.
Ovaries - didelphic.
Tail - blunt end in female and male long tail with bursa.

22. How does it affect the plants?
Nematode penetrates root directly
Nematode invading root cortex
Invaded tissues turn brown
Nematodes reproduce and migrate within the
root.
Invaded cortical tissues collapse and break down
Young root may be girdled and their distal
portions killed

24. LIFE CYCLE
It completes its life cycle within the root cortex, however,
juveniles and adults are also present in rhizosphere soil.
Optimum reproduction occurs at around 30°C.
It does not reproduce below 16-17°C or above 33°C.
ranges between 24 and 32°C.
it completes its life cycle in 20-25 days,

26. Symptoms
• Poor growth
• fruit size - Small
• Prone to toppling over under high wind
pressure .
• Purplish streak on the young root.
• Reddish brown lesions throughout the cortex

27. Control measures
• Azadirachta indica and Allium sativum – apply
extract
• Paecilomyces lilacinus -(fungus)parasitizes
eggs, juveniles and adults of R. similis. It can
be applied as dip, soil drench or incorporated
into the soil. It is marketed commercially.
• Pseudomonas fluorescens -(bacteria) inhibit
invasion of R.similis.

28. • Nematicides are generally non-volatile
organophosphates or carbamates. Their mode of
action is mainly nematostatic, which means they
do not kill nematodes, but act on the nematodes’
nervous system and interfere with their ability to
hatch from eggs, move, penetrate the roots, feed
and reproduce.
• Though nematicides are generally effective in
controlling nematodes and are easy to use, they
are expensive, highly toxic and may have a
negative impact on the environment

29. References
1. Cobb, N.A. 1893. Nematodes, mostly Australian and Fijian. F.
Cunninghame and Co., Sydney, Australia. 84p.
2. Wehunt, E.J. and Edwards, D.I. 1968. Radopholus similis and
other nematode species on bananas. p1-19. In: Smart, G.C.
and Perry, V.G. (eds.). Tropical Nematology. University of
Florida Press, Gainesville, U.S.A.
3. Stover, R.H. 1972. Banana, plantain and abaca diseases.
Commonwealth Mycological Institute, United Kingdom. 316p.
4.The royal horticultural society PESTS & DISEASES.
5.http://www.musarama.org/upload/high/toppled-plant.jpg

30. Thank U