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ALFALFA NEMATODES: WHAT CAN BE DONE?BECKY B. WESTERDAHL

EXTENSION NEMATOLOGIST /PROFESSOR OF NEMATOLOGY

WWW ADDRESS:ucdnema.ucdavis.edu

DECEMBER 3, 2008

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TYPICAL PLANT PARASITIC NEMATODE

SPEAR

ESOPHAGUS

MEDIAN BULBNERVE RING

EXCRETORYPORE

ANUS

S B

MALE TAIL

VULVA

OVARY

INTESTINE

S=SPICULESB=BURSA

BASAL GLANDS

http://ucdnema.ucdavis.edu

CUTICLE

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NEMATODES AREAQUATIC ORGANISMS

THEY LIVE INTHE FILM OF WATERLINING SOIL PORES

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LIFE CYCLE OF A TYPICAL PLANT PARASITIC NEMATODE:

EGG

ADULT

J1 J2J3

J4

J = JUVENILE OR LARVA

MM

MM

TIME

SIZE

B. A. JAFFEE

B. A. JAFFEE

M = MOLT

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ECTOPARASITES IN ALFALFA:SCIENTIFIC NAME - COMMON NAME -Xiphinema americanum Dagger Longidorus africanus NeedleCriconemella curvatus RingMerlinius brevidens StuntTylenchorhynchus sp. StuntHelicotylenchus sp. SpiralTrichodorus sp. Stubby RootParatrichodorus sp. Stubby Root

ECTOPARASITE

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ENDOPARASITES IN ALFALFA:SCIENTIFIC NAME - COMMON NAME -Ditylenchus dipsaci Stem & BulbPratylenchus penetrans Root LesionMeloidogyne hapla Northern Root KnotMeloidogyne javanica Javanese Root KnotMeloidogyne incognita Southern Root KnotMeloidogyne arenaria Peanut Root KnotMeloidogyne chitwoodi Columbia Root Knot

MIGRATORY ENDOPARASITE

SEDENTARYENDOPARASITE

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DITYLENCHUS DIPSACI - STEM & BULB• First found in Germany in 1881• First found in U.S. in 1923• At least 20 morphologically indistinguishable

races• Optimum temperatures 59-68 F (15-20C)• Time for one generation 19-23 days• Reproductive range 41-86 F (5-30 C)• Most severe in moist, cool weather• 4th stage juvenile is a dessication resistant

survival stage

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SYMPTOMS & SIGNS OF NEMATODE DAMAGE TO ALFALFA:

VISIBLE ABOVE GROUND - ROOT SYMPTOMS -Stunting Galls or SwellingsChlorosis Stubby RootsMid-day Wilting Lesions or Dark SpotsLeaf Drop StuntingYellowingCurling and Twisting of Leaves

and StemsPatches of Poor Growth in FieldLack of Response to TreatmentReduced Yield"Unthriftiness"

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ROOT-KNOT NEMATODE ON ALFALFA:

BENEFICIAL NITROGEN FIXING NODULES

ROOT-KNOT NEMATODE GALLSUCD A

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HOW NEMATODES INJURE ALFALFA:

1. Mechanical injury - penetration & movement through tissues.

2. Cellular changesA. Death of cells (necrosis)B. Changes in growth of cells

3. Physiological changes in hostA. Interruption in uptake and flow of water and nutrients

from roots.B. Interruption in flow of food from leaves to roots.

4. Create openings for entry of other microorganisms5. Increase susceptibility to environmental stress.

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SAMPLING FOR NEMATODES:

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SAMPLING FOR NEMATODES ON ALFALFA:

Sample part of plant affected (roots, stems, leaves)In soil, dig into root zone where moisture is presentPlace soil and small roots into plastic bagSoil from several places can be combinedCollect about 1 quart of soil and rootsSample healthy areas also and place in separate bagSeal bags and keep cool (do not freeze)Label bags - name, address, sample location, date, crop

history, existing crop, next proposed cropNotify laboratory that is to receive samplesUCD A

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MANAGEMENT OF ROOT-KNOT AND STEM AND BULB NEMATODE ON ALFALFA:

SELECTION OF PLANTING SITECERTIFIED SEEDCLEAN EQUIPMENTIRRIGATION MANAGEMENT (FOR D. DIPSACI)WEED MANAGEMENT (FALL BURNING FOR D. DIPSACI)CHOICE OF VARIETYCROP ROTATION (FOR D. DIPSACI)FALLOWCHEMICALS UCD A

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USE OF RESISTANT & TOLERANT VARIETIES:

Immune - plants do not allow nematode attack, including initial root invasion.

Resistant or nonhost - plants may be invaded by nematodes and may show damage, but chemical or physical unsuitability of the plant will prevent population increases.

Susceptible - plants allow normal nematode reproduction and may or may not tolerate nematode attack.

Tolerant host - plants are able to withstand nematode attack.

Intolerant host - plants are more likely damaged by nematode attack.

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NEMATODE / HOST ASSOCIATION DATABASES

H. FERRIS, E. CASWELL-CHEN, B. WESTERDAHLFROM URL: http://ucdnema.ucdavis.edu/

SELECT: VIEW DATABASES

NEMABASE Nematode-Host Association Database(can also be obtained from ucipm website)

Nematode Common-Scientific Name DatabasePlant Common-Scientific Name DatabaseLownsbery Nematode-Host Association

DatabaseRadewald California Ornamental

Nematode-Host Association DatabaseNematode Primer DatabaseKnowledge Planning Database

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SOIL AMENDMENTS / NATURAL PRODUCTS TESTED 1991-1999:

FAREWELL MICROLIFEMICROPLEX F-68 SOIL CONDITIONERCLANDOSAN 618 SUPERBACAGROSYN GUANO PLUSQUINOA SESAMEHUMIC ACID COMPOSTDITERA OZONEAGRI-50 PENT-A-VATEARISE FERTILAIDZAP AMMONIUM SULFATEUCD A

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B. A. JAFFEE

POSSIBLE MODES OF ACTION OF SOIL AMENDMENTS / NATURAL PRODUCTS:

ADDITION OF BENEFICIAL MICROBIALSSTIMULATION OF NEMATOPHAGOUS FUNGICOMPETITION FOR ROOT SURFACEREDUCE STRESS ON NEMATODE INFESTED

PLANTS (VIA IMPROVED SOIL STRUCTURE,SOIL WATER RETENTION, PLANT NUTRITION)

PRODUCE NEMATICIDALBREAKDOWN PRODUCTS

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DOING YOUR OWN FIELD TESTING:

UNTREATED AREASREPLICATIONRANDOMIZATIONCHEMICAL STANDARD

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BIOLOGICAL CONTROL: PREDATORS

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BIOLOGICAL CONTROL: PARASITES

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METHYL BROMIDE - ALTERNATIVE FUMIGANTS:1,3 - DICHLOROPROPENE

TELONE II, TELONE C35INLINE (EMULSIFIABLE)

CHLOROPICRIN (PIC EC)SODIUM TETRATHIOCARBONATE (ENZONE) METAM SODIUM DAZOMET (BASAMID)OZONE GAS*METHYL IODIDE (IODOMETHANE)*PROPARGYL BROMIDE

COMBINATIONS OF THE ABOVE

*NOT REGISTERED

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COMPOUND VOLATILITY $/ACREHIGH HIGH

FUMIGANTS Methyl Bromide - Tarped 5

- Nontarped 5Chloropicrin 71,3-Dichloropropene(1,3-D.TeloneII) 30

Methyl isothiocyanate 500( Metam Sodium, Vapam, Basamid)

ORGANOPHOSPHATES & CARBAMATESEthoprop(Mocap) 100,000Carbofuran(Furadan) 1,000,000Aldicarb(Temik) 1,500,000 Fenamiphos(Nemacur) 10,000,000Oxamyl(Vydate) 100,000,000

LOW LOW

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STEM AND BULB NEMATODE ON ALFALFA:

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ECTOPARASITE

MIGRATORY ENDOPARASITE

SEDENTARYENDOPARASITE

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THE MOST COMMON GENERA OFPLANT PARASITIC NEMATODES IN CALIFORNIA:

ECTOPARASITES MIGRATORY ENDOPARASITES

*Trichodorus - Stubby Root *Pratylenchus - Lesion*Xiphinema - Dagger *Ditylenchus - Stem & Longidorus - Needle BulbHelicotylenchus - Spiral Aphelenchoides - Foliar*Criconemella - RingParatylenchus - Pin SEDENTARY Hemicycliophora - Sheath ENDOPARASITES

*Meloidogyne - Root KnotSOME GENERA CONTAIN Anguina - Seed & Leaf Gall SEVERAL IMPORTANT Tylenchulus - Citrus SPECIES Heterodera - Cyst

*LIKELY TO CAUSE PROBLEMSON ALFALFA

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