e a lintang wardyani h0713059 at-i nematodes

8/10/2019 E A Lintang Wardyani H0713059 at-I Nematodes

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Assalamualaikum wr. Wb

E. A Lintang Wardyani

H0713059


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General Definition

Nematodes are roundworms,

and those that attack plants are

microscopic.

The damage they caused to

plants is often subtle and easily

confused with nutrient

problems


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General Characteristic of Nematodesa. Most nematodes are very small, even microscopic

b. 0.25 mm to 3 mm long ( 1 / 100 " to 1 / 8 ") and cylindrical,

tapering toward the head and tailc. colorless;

d. most live hidden in soil, under water, or in the plants or

animals they parasitized

e. relatively few have obvious direct effects on humans or

their activities

f. Females of a few species lose their worm shape as they

mature, becoming pear-, lemon- or kidney- shaped

g. possess all of the major organ systems of higher animals

except respiratory and circulatory systems.

h. The body is covered by a transparent cuticle, which bears

surface marks helpful for identifying nematode species


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Morphology

A nematode has:

1. Digestive organs

2. Reproductive

organs

3. Excretorystructures

4. Muscles5. Nerves

6. Tough skin or

Cuticle


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Disease Symptoms

The symptoms of nematode disease are

commonly those of root impairment, such as growth reduction,

increased wilting,

mineral-deficiency symptoms, decreased winter-hardiness,

and dieback in perennials

For more details there are two ways todistinguish the symptoms


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Disease SymptomsTop Symptoms:

transform floral parts

producing characteristic galls in place of normalseeds.

produce galls and distortion in leaves and stem.

swelling and distortion of stems and leaves.

foliar discoloration.

however, the above ground symptoms of nematodeinfection are indirect and are rather nondescript,such as reduction in vigor, stunting, yield decline, or

chlorosis.


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Foliar Symptoms-

Aerial View


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Foliar Symptoms

Oval Pattern


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Foliar Symptoms-

Plant Death


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Foliar Symptoms-

Stunting


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Foliar Symptoms-

Leaf Yellowing


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Foliar Symptoms-

Stunting


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Foliar Symptoms-

Slow Decline


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Foliar Symptoms-

Toppling


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Disease SymptomsRoot Symptoms:

apical root-galling apical galling

Lesion nematodes produce characteristic lesions in

the root cortex of plants. Female cyst nematodes can be seen on the roots of

host plants if the soil is carefully removed from theroots. Care must be taken to discriminate cysts

from legume nodules, however. Soil clings to a gelatinous matrix secreted by the

citrus nematode, causing infected citrus roots toappear dirtier than uninfected ones.


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Root Symptoms- Galling


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Root Symptoms- Cyst Nematodes

on Roots


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Root Symptoms-

Peanut Pod Galling


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Root Symptoms-

Lesions


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Root Symptoms

Sweet Potatoes


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Root Symptoms -

Irish Potatoes


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Root Symptoms-

Potato Rot Nematode


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Root Symptoms-

Sprangling


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Classifications:

The majority of plant parasiticnematode species are in the class

Chromodorea, order Rhabditida

(formerly placed in the order

Tylenchida). There are some major

types of nematode feeding

strategies used by plant parasitic

nematodes


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Nematodes may be grouped by feeding habit as:

Ectoparasitic:nematodes feed on plant tissues

from outside the plant; Endoparasitic:nematodes feed inside the

tissues.

Semi-endoparasitic:part of body inside planttissues.

By movement when feeding, they are called:

Sedentarymostly immobile during their life Migratorymobile for all their life.


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Feeding Habits of Some Plant-

parasitic Nematodes

Root-knot

Lesion


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Cyst


parasitic Nematodes

Ring


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parasitic Nematodes

Stubby root

Reniform


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The Important Groups

Root-knot nematode

Reniform nematode

Burrowing and lesion nematodes Sugar-beet cyst nematode

Foliar nematode

k d


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Root-knot Nematodes

Root-knot nematodes belong to the genus Meloidogyne. The

two most common species in Hawaii are M. incognita(southern root-knot) and M.Javanica (Javanese root-knot);

other species are present but occur less frequently.

The root-knot nematodes feed and mature inside the roots ofplants. Their feeding induces abnormal enlargements of theroot called galls. The root-knot nematode does not survivevery long without a host plant, except in very low numbersand probably in the egg stage.

Diagnosis: Root galls are the primary symptom of

root-knot nematodes. Species identification requires

laboratory assay.


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Reniform nematode

The reniform nematode, Rotylenchulus reniformis, feeds

on many cultivated and noncultivated plants. Thejuvenile stages and males live in the soil and do not feed.The adult female is swollen and is the only parasitic stageof this nematodes life cycle. The female inserts her head

and neck into the root, leaving her body outside of the

root. The reniform nematode survives in the soil as eggsand coiled juveniles.

This nematode causes root rotting and reduced uptakeof water and soil nutrients.

The symptoms are general lack of vigor anddiscoloration of foliage, and (or) stunted plants.

Diagnosis: The reniform nematode can be accurately

diagnosed only through laboratory assay of a soil sample.

d l d


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Burrowing and lesion nematodes

Adult burrowing nematodes (Radopholussimilis) and

lesion nematodes (Pratylenchusspp.) cause root rot.These worm-shaped nematodes are migratory, livingmost of their life, including the hatching and feeding

stages, inside the roots and sometimes the lower

stem of their host plants. They can move through thesoil from one root to another during their life cycle.

Diagnosis: The root rot caused by this nematode is

not characteristic for diagnosis. It is necessary to have

the soil and roots assayed to determine the numbers

and kinds of species present; root assays are the most

reliable.


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Sugar-beet cyst nematode

Sugar-beet cyst nematode (Heteroderaschachtii), ispriarily a problem on cabbage, broccoli, and cauli

flower. This nematode penetrates the root, and thefemale enlarges as it matures to become a white,

lemon-shaped structure that breaks through the rootsurface at maturity. When the female dies, her bodyturns brown. Eggs survive inside the dead female

body (called a cyst) for many years.

Diagnosis: Direct observation of the organism with a magnifying glass is helpful,because the white cysts are about the size of the period at the end of thissentence. Root aphids are also white, so some experience may be needed todifferentiate between these two white structures clinging to the roots.Confirmation by a diagnostic laboratory is recommended.


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Foliar nematode

Aphelenchoides besseyi,A. ritzema-bosi, andA.

fragariaefeed inside foliage. The entirenematode life cycle is completed in the leaves.

Plants can be stunted with deformed, discolored,

or dying leaf tissue; dieback can also occur.

Diagnosis: Accurate identification requires laboratory assay of leaf-

tissue samples.


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References

https://mrec.ifas.ufl.edu/lso/SCOUT/Nematodes.pdf

http://www.ars.usda.gov/main/docs.htm?docid=9628

Jimmy R. Rich and Stanley B. Hendley, IFAS/NFREC

Introduction to Plant Parasitic Nematodes and Their

Management. University of Florida

www.ctahr.hawaii.edu/oc/freepubs/pdf/pd-15.pdf


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Thanks for your attention

Wassalamualaikum wr. wb

e a lintang wardyani h0713059 at-i nematodes

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