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OSU Nematode Testing Service - Plant-Parasitic Nematodes on Grasses

BIOLOGY, HOST RANGES, AND DAMAGE LEVELS OF ROOT-PARASITIC NEMATODES ON PACIFIC NORTHWEST GRASSES

March 1999: Version 2

plant-parasitic nematodesContents of this Survey: 

Damage Levels: An Introduction

Host designations based on gall ratings
Host designations based on Reproductive factor (Rf)
Host designations based on number of plants infected compared to number of plants inoculated

Biology of Nematode Genera:

Criconemella
Heterodera
Longidorus and Xiphinema
Meloidogyne
Paratylenchus
Pratylenchus
Trichodorus and Paratrichodorus
Tylenchorhynchus
 

Host Ranges and Damage Levels Listed Alphabetically by Grass Genus and Species

Aegilops
Agropyron
Agrostis
Alopecurus
Arrhenatherum
Avena
Beckmannia
Boutelous
Brachypodium
Bromus
Cenchrus
Cynodon
Dactylis
Digitaria
Echinochloa
Eleusine
Elymus
Elytrigia
Eragrostis
Eremochloa
Festuca
Hordeum
Koeleria
Lolium
Panicum
Pascopyrum
Pennisetum
Phalaris
Phleum
Poa
Polypogon
Pseudoroegneria
Secale
Setaria
Sorghum
Spartina
Thinopyrum
Triticum
Vulpia
Zea
 

Literature Cited

DAMAGE LEVELS: AN INTRODUCTION

How many plant-parasitic nematodes will damage a particular plant species? This is the most frequently asked question of the Nematode Testing Service at Oregon State University. This literature survey is an attempt to answer that question for grass species including cereals that grow in the Pacific Northwest. Non-quantitative host range information is also included to facilitate control through crop rotation: if remaining weeds are host to a plant-parasitic nematode, the nematode population can be maintained in the weeds even if the crop itself is not a host.

Most information listed below is from replicated studies or systematic surveys. Studies conducted in pots or microplots are indicated. Study conditions may deviate from local Oregon conditions in soil type, climate, moisture, and other factors. Cultivars often vary in susceptibility to parasitic nematode damage and in the number of nematodes they will support.

Numbers of most plant-parasitic nematodes vary seasonally. In many of these studies, the season at which samples were taken is not indicated. In some, however, nematode numbers are designated as initial or as final levels.

These studies report levels at which damage has occurred rather than predict damage that will occur. Therefore, these data are presented only to give suggestions of nematode levels at which damage may occur.

If a particular crop is not included in the list, no information has been found for that crop. If a nematode species of concern is not listed under a particular crop, no information has been found on the species for that crop. A lack of information does not necessarily imply a lack of damage.

Nematode damage numbers in this survey are expressed in this survey as nematodes/100 grams (g) soil or number of nematodes/100 cubic centimeters (cm3 or cc) soil. Numbers/100 g soil may be multiplied by 20 to give the number of nematodes/2000 g soil (traditionally designated by the OSU Nematode Testing Lab as one "quart"). Nematode numbers from the OSU Nematology Lab are reported as number/100 g and are corrected for soil moisture. Nematode numbers/100 cm3 soil can provide a rough estimate of numbers/100 g soil corrected for dry weight but should be divided by the soil bulk density for accuracy. Bulk densities of clay, clay loam, and silt loam surface soils range from about 1.0 to 1.6 g/cm3, and those of sands and sandy loams range from about 1.2 to 1.8 g/cm3 (Buckman and Brady 1969). However, the bulk density of the sample actually processed is dependent upon packing density during measurement. Since bulk densities are not frequently reported in studies in which nematode numbers are expressed on a volume basis, accurate conversion of numbers/100 cm3 to numbers/100 grams soil is not usually possible. Nevertheless, since the variation associated with bulk density conversions is generally less than the variation associated with field sampling, numbers/100 cm3 soil provide an acceptable approximation of numbers/100 g soil for making management decisions.

HOST DESIGNATIONS BASED ON GALL RATINGS

These designations apply only to Meloidogyne. A rating of "1" = no galls (resistant); "2" = 1 to 10 galls; "3" = 11 to 100 galls; "4" = more than 100 galls (susceptibile) (LaMondia 1995, LaMondia 1996).

HOST DESIGNATIONS BASED ON REPRODUCTIVE FACTOR (Rf).

Rf = final population/initial population. An Rf of over 10 indicates an excellent host; an Rf of 1 to 10 indicates a good host; an Rf of about 1 indicates a maintenance host; and an Rf of between 1 and 0 indicates a poor host or nonhost (Ferris et al. 1993).

HOST DESIGNATIONS BASED ON NUMBER OF PLANTS INFECTED COMPARED TO NUMBER OF PLANTS INOCULATED.

This is expressed as a fraction. If 10 plants were inoculated and 5 were infected, then 5/10 inoculated plants were infected (Faulkner and McElroy 1964).

BIOLOGY OF NEMATODE GENERA

CRICONEMELLA

Criconemella, the ring nematodes, are migratory root ectoparasites. Plump, stubby bodies, coarsely and strongly annulated ("ringed") cuticles, and long, heavy stylets render them distinctive even under the dissecting microscope. Adults of C. xenoplax are about 0.4 mm long. The life cycle of Criconemella is typical of all migratory root ectoparasites considered in this survey. They spend their entire lives in the soil outside the root, puncturing cells and sucking out cell liquids. Females lay eggs in the soil. The first of four molts occurs inside the egg, and the nematodes hatch as second stage juveniles (J2). The juveniles enlarge during the next two molts. Sex organs do not appear until after the fourth and final molt to adulthood. Males are necessary for reproduction in some species but not in others. Females lay eggs, and the cycle begins again. Criconemella spp. are often found in various mosses including Sphagnum and also in riverside and lakeside mud (Goodey 1951). They are often found in turf, sometimes in large numbers (Christie 1959). Criconemella curvatum and an unidentified Criconemella species have been recovered from turf in coastal and central Oregon in 1997 and 1998. Much more information on C. xenoplax exists than on most other species in the genus, and it is the only species addressed in this survey.

HETERODERA

This genus comprises the cyst nematodes, sedentary endoparasites named for the fat, exposed mature female. J2 and adult females are about 0.5 mm long, and males reach about 1.0 mm. Second stage juveniles hatch from eggs and enter new host roots near the tips, destroying cells in their paths. They establish a permanent feeding site of several cells with partially dissolved walls. Both males and females fatten at first, but during subsequent molts, the male becomes thin and motile; it leaves the root as an adult and mates with a female. The female continues to fatten in this, her permanent home, achieving nearly spherical plumpness by adulthood following the fourth molt. Cortical cells are destroyed, and the root cracks to accomodate the flourishing female, exposing all but her anterior end, which is still feeding. Eggs may remain alive packed inside the female for several years, protected by her cuticle, which becomes a leathery "cyst" after her death. J2 become active in response to root exudates. Life cycles take about 3 to 4 weeks. Most cyst nematode species have narrow host ranges. Heterodera avenae has been known in Ontario, Canada for decades (Norton et al. 1984). It was reported in Oregon in 1975 (Jensen et al. 1975). Its primary host crop is oats, but other cereals and other grasses are also parasitized. Many grasses are hosts, and even those that are not good hosts can maintain populations between cereal crops (Williams and Siddiqi 1972). Higher numbers and more severe damage have been reported in lighter soils. It completes only one generation per year (Norton et al. 1984). Hatch in increased by cereal root exudates and occurs best at 10 C, although temperature relationships are complex (Norton et al. 1984). Heterodera goettingiana, Heterodera humuli, Heterodera schachtii, and Heterodera trifolii are also present in Oregon, but they do not usually parasitize grasses. Heterodera trifolii may be the most widespread cyst nematode in North America (Norton et al. 1984), and it may be detected in grass or grain soil samples due to its parasitization of legumes which may be weeds. Recovery of Heterodera is unusual in OSU Nematode Testing Service samples. 

LONGIDORUS AND XIPHINEMA

The life histories of these two migratory ectoparasic genera, the needle and dagger nematodes, respectively, resemble that of Criconemella, but their anatomy is different. Their long stylets enable them to feed on deep tissues, and they may even penetrate the stele. This feeding causes necrosis, shrivelling, and stunting of young roots and reduction of above-ground growth as well as root galls in some cases. Both genera can vector viruses, but grasses do not appear to be hosts of the viruses vectored. Members of both genera are larger than other plant parasites, sometimes exceeding 5 mm. They are barely visible to the unaided eye when floating in clear water, but they are not visible when in soil. Xiphinema species included in this survey are limited to those detected on Pacific Northwest grasses: X. americanum, X. bakeri, and X. index (reported for Oregon (Norton et al. 1984) but rare). Longidorus elongatus is the only species known to parasitize grasses in Oregon. Longidorus sylphus and L. menthosolanus are synonyms of L. elongatus.

MELOIDOGYNE

The sedentary endoparasitic root-knot nematodes (Meloidogyne spp.) hatch from eggs and enter roots as second stage juveniles (J2), select a feeding site of three to eight cells, and swell in their chosen site as they progress through two more juvenile stages towards adulthood. They introduce hormone-like substances into the plant cells, causing the formation of a rich feeding site containing multiple nuclei and excess proteins. The resulting swellings are called galls or knots. Males regain their slender profiles and leave the root at adulthood, but the fattened adult females remain inside, exuding eggs into the soil within a gelatinous matrix. First stage juvenile nematodes (J1) develop within the eggs, undergo their first molt to J2, hatch, and migrate through soil before entering host plant roots. Adult females are about 0.7 mm long, J2 are about 0.4 mm long, and males are 1-2 mm long. Roots inhabited by root-knot nematodes often have visible galls and may exhibit excessive branching. Parasitized plants may be weak and stunted, and root systems may be deformed. However, galling is not essential for nematode feeding, and gall development may be inconspicuous or absent on some hosts (Kleynhans et al. 1996). Meloidogyne species included in this survey are those detected on or associated with Oregon agricultural crops, weeds, and native plants. These are M. hapla, M. chitwoodi, and M. naasi. Meloidogyne chitwoodi reproduces better during cool growing seasons than does M. hapla, but both species have a higher tolerance for cooler soil temperatures than most other common North American Meloidogyne species (Nyczepir et al. 1982, Norton et al. 1984). The optimum temperatures for M. hapla life cycle completion are 25 to 30°C (Norton et al. 1984). Meloidogyne naasi survived well at 16°C and reproduced between 16 and 32°C, but reproduction was best at 27°C (Norton et al. 1984). Small grains and cereals are good hosts for M. chitwoodi, but most are non-hosts for M. hapla (Nyczepir et al. 1982), as are other grasses. Meloidogyne naasi is a parasite primarily of Poaceae and Chenopodiaceae, often doing greater damage in wet and compacted soils.

PARATYLENCHUS

The life cycle of the migratory ectoparasitic pin nematodes resembles that of Criconemella. Adults are about 0.4 mm long. Paratylenchus in our area cannot be identified to species because they belong to one or more undescribed species. Thus, damage levels by nematode species cannot be listed. Paratylenchus is not considered damaging on most crops except in high numbers, usually 500/100 g soil or more. They have been recovered from grass samples by the OSU Nematode Testing Service.

PRATYLENCHUS

The migratory endoparasitic root-lesion nematodes (Pratylenchus spp.) create holes in root cells and crawl inside. They move longitudinally through the cortex, piercing, sucking, and leaving behind a trail of eggs and toxic metabolites. Eggs deposited in both roots and soil hatch, and the life cycle continues through four molts to sexual maturity and reproduction. Root cell death results in brown longitudinal root lesions, which begin on one side but may eventually encircle a root and thereby girdle it. The overall effect is a weak, shallow root system with extensive dead areas. Pratylenchus spp. are disseminated by transportation of soil or plant parts and by surface or irrigation water (Evans et al. 1993). Adults are about 0.5 mm long. Pratylenchus species included in this survey are limited to those detected on Oregon agricultural crops: P. crenatus, P. neglectus, P. penetrans, and P. thornei. Pratylenchus crenatus, formerly known as P. pratensis, reproduces best at 10-15°C in sand or silt loam (Norton et al. 1984). Its wide host range includes many grasses. Pratylenchus neglectus is synonymous with P. minyus (Norton et al. 1984). It has a very wide host range. Populations after 70 days were highest on peppermint at 24°C when both the nematode and Verticillium dahliae were present (Faulkner and Bolander 1969). It penetrated host roots better in sandy loam than in silt loam soils (Brown et al. 1980). Pratylenchus penetrans also has a very wide host range. Its density does not appear to be affected by soil texture (Norton et al. 1984). Reproduction in peppermint was much greater at 30°C than at 22.5°C and 15°C (Patterson and Bergeson 1967). However, population increase was greatest on potatoes at 16°C and on corn at 24°C (Acosta and Malek 1979). Pratylenchus thornei has been recovered from a variety of plant species but is most commonly associated with grasses. It can cause marked damage on wheat and barley.

TRICHODORUS AND PARATRICHODORUS

These two genera, the stubby-root nematodes, are distinguished only by characteristics visible under high compound microscope magnification. Adults are about 0.7 mm long. They have slender, curved stylets and stout, blunt-ended bodies. Species included in this survey are limited to those detected on Oregon agricultural crops or those in nearby states and provinces: P. allius, P. minor (formerly T. christei), P. teres, Trichodorus aequalis, and T. obscurus. Only P. allius has been positively identified by the OSU Plant Clinic Nematode Testing Lab. The life cycle of this migratory ectoparasite resembles that of Criconemella. The nematodes feed mostly at root tips but also along the sides of young, succulent roots. Root tip growth is slowed or stopped, resulting in a generally stunted root system or in short, stubby roots. Like Xiphinema and Longidorus, stubby- root nematodes can vector plant viruses, but none appear to be problems on grasses. According to Norton et al. (1984), Paratrichodorus allius reproduced between 21 and 26°C. Lighter textured soils supported the highest numbers. The life cycle of P. minor is completed in 21-22 days at 22°C and in 16 - 17 days at 30°C; the optimum temperature for reproduction is 25°C. Optimum soil moisture for reproduction is near 10%. In cranberry bogs, populations peaked in November and December. In Georgia, they peaked in June.

TYLENCHORHYNCHUS and similar genera

These are migratory root ectoparasites whose life cycle resembles that of Criconemella. Because their feeding can result in a stunted root system, they are called "stunt nematodes." Adults are about 0.6 to 0.8 mm long. Tylenchorhynchus and related genera are commonly recovered from Pacific Northwest soils. Because they appear to do little damage, however, little attention is paid to them, and the genera involved remain in question. Tylenchorhynchus claytoni occurs in Oregon (Norton et al. 1984).

HOST RANGES AND DAMAGE LEVELS LISTED BY GRASS GENUS AND SPECIES

Aegilops cylindrica (jointed goatgrass)

Meloidogyne chitwoodi: In pots, trace reproduction: very poor host (O'Bannon et al. 1984).

Agropyron complex (wheatgrasses): A. cristatum, A cristatum X desertorum, A desertorus, A. riparium, A. trachycaulum, A. trichophorum, Elymus lanceolatus, Elytrigia repens, Pascopyrum smithii, and Thinopyrum intermedium

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)
Meloidogyne chitwoodi: Nordan, Fairway, and Highcrest were suppressed about 24 to 40% at 185 eggs/100 cc and about 29 to 56 % at 926 eggs/100 cc inoculations of Utah, Idaho, California, and Washington populations at planting (Griffin and Asay 1989). Mean Rf: 16.5 (Jensen and Griffin 1994). Nordan is a good host (Rf = 2.8) (Griffin et al. 1984). Meloidogyne hapla: In pots, Agropyron cristatum, A. desertorum, A. riparium, and A. trichophorum were not susceptible, and no inoculated plants were infected (Faulkner and McElroy 1964).
Pratylenchus neglectus: Initial density of 400/100 cm3 soil reduced cv. Hycrest Crested, Fairway Crested, Nordan Crested, Greenar Intermediate, and Secar Snake River shoot weights by 22 to 49% and root weights by 26 to 42% (Griffin 1992b). Greatest yield reduction was at 800/100 cm3 soil, but damage observed at 200/100 cm3 (Griffin & Jensen 1997). Pratylenchus penetrans: A. cristatum, A. intermedium, and A. trachycaulum Primar were experimentally infected with P. penetrans (Jensen 1953).
Xiphinema americanum: Fairway crested (Agropyron cristatum), Hycrest crested (A. cristatum X A desertorum), "Rosana" western (Pascopyrum smithii), "Oahe" intermediate (Thinopyrum intermedium), and RS-1 hybrid (Elytrigia repens X Pseudoroegneria spicata) are hosts (Griffin et al. 1996). Agropyron mongolicum (Mongolian wheatgrass)
Meloidogyne chitwoodi
Mean Rf: 4.5 (Jensen and Griffin 1994).

Agropyron repens (quackgrass)

Meloidogyne chitwoodi: In pots, trace reproduction: very poor host (O'Bannon et al. 1984).
Meloidogyne naasi: Host for 4 US and 1 English population (Michell et al. 1973a).

Agrostis canina (Astoria bentgrass)

Meloidogyne naasi: Host for 4 US and 1 English population (Michell et al. 1973a).
Xiphinema americanum: In pots, 169 days after inoculation with 72/100 g soil, the final population was 8/100 g soil (Miller 1980).

Agrostis palustris (= A. alba; creeping bentgrass, redtop)

Meloidogyne hapla: In pots, redtop as not susceptible, and none of 23 inoculated plants were infected (Faulkner and McElroy 1964). Penncress and Seaside are hosts (Radewald et al. 1966, Radewald et al. 1970). Meloidogyne naasi: 67/100 cm3 soil in pots alone and with 67/100 ml of both Pratylenchus penetrans and Tylenchorhynchus agri significantly reduced top growth and in root weight after 10 but not 6 months (Sikora et al. 1972). 24/100 cm3 soil in pots resulted in densities of 84 to 1763/g root after 8 months; all but one of 5 races caused significant reduction in top weights but usually not root weights (Michell et al. 1973b). Causes severe damage (Franklin 1973). Toronto C-15 is a host for 3 US but not California and English populations (Michell et al. 1973a). Host for 4 US and 1 English population of redtop (Michell et al. 1973a).
Pratylenchus penetrans: In pots, inhibited top growth only when co-inoculated with Meloidogyne naasi. A. palustris is a poor host for Pratylenchus penetrans (Sikora et al. 1972). 

Agrostis tenuis (colonial bentgrass)

Meloidogyne naasi: Highland is a host (Radewald et al. 1970).

Agrostis sp . (Bentgrass, unspecified)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972).
Longidorus elongatus: Associated (Norton et al. 1984).
Pratylenchus thornei: Host in Mexico (Fortuner 1977).

Alopecurus pratensis (meadow foxtail)

Meloidogyne chitwoodi: In pots, no reproduction: non-host (O'Bannon et al. 1984).
Pratylenchus penetrans: Tualatin was experimentally infected with P. penetrans (Jensen 1953).

Alopecurus spp. . (Foxtail)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Arrhenatherum elatius (onion twitch, tall oatgrass)

Meloidogyne chitwoodi: In pots, no reproduction: non-host (O'Bannon et al. 1984).
Meloidogyne naasi: Host (Franklin 1965).
Pratylenchus penetrans: Experimentally infected with P. penetrans (Jensen 1953). 

Avena fatua (wild oats)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972). Host in New Zealand (Knight et al. 1997). Heterodera schachtii: Host (Bendixen et al. 1979)

Avena nuda

Xiphinema americanum: In pots, 169 days after inoculation with 72/100 g soil, the final population was 0/100 g soil (Miller 1980).

Avena sativa (oats)

Heterodera avenae: Causes stunting and chlorosis, branched root systems, and patchy growth, grain formation is inhibited (Kleynhans et al. 1996). Its main effect is suppression of root elongation (McGawley and Overstreet 1998). Host (Williams and Siddiqi 1972). Severely affected (Christie 1959).
Heterodera schachtii: Host (Bendixen et al. 1979)
Meloidogyne chitwoodi: In pots, Ottawa and Cayuse were good hosts (Rf = 6.5 and 4.2) for race 1 (Ferris et al. 1993). In pots, Park was a is a suitable host (Rf = 24.5) for Race 2 (alfalfa race) (Mojtahedi et al. 1988b). In pots, cv. Appaloosa, Cayuse, Corbit, Markton, Menominee, Otana, Random, and Terra suppored high reproduction: very good hosts. Park supported high reproduction: good host (O'Bannon et al. 1984). At 500 eggs/liter soil, Park roots but not top growth weighed less than uninoculated controls; at 5000 eggs/liter, total plant dry weight was less than uninoculated controls M. chitwoodi increased from 8 to 11 times on Park oats (Santo and O'Bannon 1981). In pots, Rf of 2.3 on Park from inoculation of approximately 200/100 cm3 soil (Santo et al. 1980).
Meloidogyne hapla: In pots, not susceptible, and 0/16 inoculated plants were infected (Faulkner and McElroy 1964). In pots, "Lee" was a host (Gaskin and Crittenden 1956). In pots, Rf of 0 on Park from inoculation of approximately 200/100 cm3 soil (Santo et al. 1980).
Meloidogyne naasi: Wintok is a host for four US and one English population (Michell et al. 1973a). Sierra is a host (Radewald et al. 1970). Red rustproof, Chinese Hull-less, Swedish select, Algerian, Pusa Hybrid J. Canuck, Sure Grain, Avoine-crena, and Punjab Algerian are resistant; some of these varieties are from Asia and South America (Siddiqui and Taylor 1970). Diane acts as a trap crop: it is heavily invaded by J2, none of which was found to develop beyond the second stage (Franklin 1973). Pratylenchus spp.: Moderately damaged (Kleynhans et al. 1996). Pratylenchus crenatus: Damage occurs at 33/100 cm3 soil (Barker et al. 1976).
Pratylenchus penetrans: In pots, initial populations of 33/100 g soil resulted in 150/g root and little necrosis after 3 months (Miller 1978). In pots, 796% increase of initial inoculum on Vicar (McDonald and Mai 1963). Pratylenchus thornei: Host in California (Siddiqui et al. 1973). Serious parasite in Utah. Severe stunting follows attach of young, succulent roots. Heads bore substandard grain numbers. Associated with severe smut attack (Thorne 1961).
Xiphinema americanum: Host in commercial crops in California (Siddiqui et al. 1973).

Beckmannia syzigachne (sloughgrass)

Meloidogyne naasi: Host (Jensen et al. 1968).

Boutelous curtipendula (side-oats, grama)

Tylenchorhynchus claytoni: Pathogenic (Bernard et al. 1998).

Boutelous gracilis (side-oats, grama)

Xiphinema index: Associated (Norton et al. 1984).

Brachypodium spp. (false brome)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Bromus inermis (smooth bromegrass)

Meloidogyne spp. Host for all major Meloidogyne spp. (Cook and Yeates 1993).
Meloidogyne hapla: In pots, Manchar was not susceptible, and 0/3 inoculated plants were infected (Faulkner and McElroy 1964).
Meloidogyne chitwoodi: Good host (Griffin et al. 1984). Reproduces (Bernard et al. 1998).
Pratylenchus penetrans: In pots, initial populations of 33/100 g soil resulted in 40/g root and moderate necrosis on Smooth Saratoga after 3 months (Miller 1978).
Pratylenchus neglectus: Reproduced well (Townshend and Anderson 1976).

Bromus mollis (Soft chess)

Criconemella xenoplax: In pots after senescence, Rf 0.53 from initial population of 33/100 cm3 soil on cv. "Blando" (Zehr et al. 1990).

Bromus tectorum (downy brome, downy chess)

Meloidogyne chitwoodi: In pots, trace reproduction: very poor host (O'Bannon et al. 1984).
Meloidogyne hapla: In pots, non-susceptible, and 0/3 inoculated plants were infected (Faulkner and McElroy 1964).

Bromus spp . (Brome, unspecified)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Cenchrus incertus (field sandburr)

Meloidogyne chitwoodi: In pots, no reproduction: non-host (O'Bannon et al. 1984).

Cynodon dactylon (Bermuda grass)

Criconemella ornata: 200-400/100 cc often occur without apparent damage (R M. Giblin-Davis, pers. comm.). The mininum number in turf in Florida that may justify nematicide application is 500/100 cc (Dunn and Noling 1997.)
Criconemella xenoplax: In pots, after 90 days, Rf was 0.79 (common bermudagrass) and 0.22 (coastal bermudagrass) times initial populations of 250/100 cm3 soil: non-hosts (Zehr et al. 1986).
Meloidogyne chitwoodi: In pots, trace reproduction: very poor host (O'Bannon et al. 1984).
Meloidogyne hapla: Can reproduce on bermudagrass (Riggs et al. 1962).

Cynodon spp . (Bermuda grass)

Paratrichorodus minor: Pest (Cook and Yeates 1993). 

Dactylis glomerata (orchardgrass)

Criconemella xenoplax: In pots after senescence, Rf was 1.88 times initial population of 33/100 cm3 soil on cv. Durar (Zehr et al. 1990). D. glomerata did not suppress C. xenoplax when grown in association with peach trees (Whittington and Zehr 1992). In pots, after 90 days, Rf was 0.61 times initial population of 250/100 cm3 soil: non-host (Zehr et al. 1986). Densities were no higher than those in fallow treatments: non-host (Lownsbery 1964).
Meloidogyne chitwoodi: In pots, moderate reproduction: moderate host (O'Bannon et al. 1984). Very good host (Griffin et al. 1984).
Meloidogyne hapla: In pots, Potomac was not susceptible, and 0/7 inoculated plants were infected (Faulkner and McElroy 1964).
Meloidogyne naasi: Host for 4 US and 1 English population (Michell et al. 1973a). Host (Franklin 1965).
Paratrichorodus minor: Pest (Cook and Yeates 1993).
Pratylenchus penetrans: In pots, initial populations of 33/100 g soil resulted in 270/ g root and moderate necrosis after 3 months (Miller 1978). Pratylenchus neglectus: Reproduced well (Townshend and Anderson 1976).
Xiphinema americanum: In pots, 169 days after inoculation with 72/100 g soil, the final population was 56/100 g soil (Miller 1980). Supported densities 5 times higher than those in fallow treatment (Lownsbery 1964). Xiphinema bakeri: In pots, heavy damage and 360% population increase after 12 weeks (McElroy 1972). 

Digitaria decumbens (Digitgrass)

Criconemella xenoplax: In pots, after 90 days, Rf was 0.10 on Pangola and 0.06 on Transvala from initial population of 250/100 cm3 soil: non-hosts (Zehr et al. 1986).

Digitaria ischaemum and D. sanguinalis (crabgrasses)

Pratylenchus penetrans: Host; P. penetrans was more abundant where rye (Secale cereale) and crabgrass (Digitaria ischaemum and D. sanguinalis) had been grown than where buckwheat (Fagopyrum esculentum) and pigweed (Amaranthus retroflexus) had grown the previous season. Thereafter, P. penetrans remained high in crabgrass plots, moderately low in buckwheat plots, and fluctuated in rye and pigweed plots (Miller and Aherns 1969).

Digitaria sanguinalis (hairy crabgrass)

Criconemella xenoplax: In pots, after 90 days, Rf was 0.22 times initial population of 250/100 cm3 soil: non-host (Zehr et al. 1986).
Meloidogyne naasi: Host for 4 US and 1 English population (Michell et al. 1973a).

Digitaria spp . (crabgrasses)

Longidorus elongatus: Associated (Norton et al. 1984).

Echinochloa crusgalli (barnyard grass or cockspur)

Criconemella xenoplax: In pots, after 90 days, Rf was 0.42 times initial population of 250/100 cm3 soil: non-host (Zehr et al. 1986).
Meloidogyne chitwoodi: In pots, light reproduction: poor host (O'Bannon et al. 1984).
Meloidogyne hapla: In pots, Rf = 0 (Belair and Beniot 1996). In pots, not susceptible, and 0/3 inoculated plants were infected (Faulkner and McElroy 1964).
Xiphinema bakeri: In pots, light damage and 544 % population increase on Danish after 12 weeks (McElroy 1972).

Echinochloa frumentacea (Japanese millet)

P. penetrans: 207% increase over initial inoculum (McDonald and Mai 1963).

Echinochloa spp . (barnyard grass)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Eleusine indica (goosegrass)

Criconemella xenoplax: In pots, after 90 days, Rf was 0.00 times initial population of 250/100 cm3 soil: non-host (Zehr et al. 1986).

Elymus canadensis (wildrye)

Pratylenchus penetrans: Experimentally infected with P. penetrans (Jensen 1953).

Elymus cinereus (Great Basin wildrye)

Meloidogyne chitwoodi: Poor host (Rf = 0.1) (Griffin et al. 1984).

Elymus lanceolatus See Agropyron complex.
Elymus sibericus (Siberian wildrye)

Meloidogyne hapla: In pots, not susceptible, and 0/4 inoculated plants were infected (Faulkner and McElroy 1964).

Elymus spp. See Pseudoroegneria spicata: (bluebunch wheatgrass). (Elymus is a synonym for Pseudoroegneria).
Elytrigia intermedia (intermediate wheatgrass)

Meloidogyne chitwoodi: Nonhost (Rf = 0) (Griffin et al. 1984).

Elytrigia repens See Agropyron complex.
Eragrostis orcuttiana (lovegrass)

Meloidogyne chitwoodi: In pots, light reproduction: poor host (O'Bannon et al. 1984).

Eremochloa opiuroides (Centipede Grass)

Criconemella xenoplax: Did not suppress C. xenoplax when grown in association with peach trees (Whittington and Zehr 1992). In pots, after 90 days, Rf was 0.12 times initial population of 250/100 cm3 soil: non-host (Zehr et al. 1986).

Festuca arundinacea (tall fescue)

Criconemella xenoplax: In pots, after 90 days, Rf was 1.01 times initial population of 250/100 cm3 soil: host (Zehr et al. 1986).
Meloidogyne chitwoodi: In pots, moderate reproduction: moderate host (O'Bannon et al. 1984).
Meloidogyne hapla: In pots, Alta was not susceptible, and 0/3 inoculated plants were infected (Faulkner and McElroy 1964).
Meloidogyne naasi: Reproduction and growth (Bernard et al. 1998). Paratrichodorus minor: Host (Bernard et al. 1998).
Pratylenchus penetrans: Alta was experimentally infected with P. penetrans (Jensen 1953). Reproduced (Bernard et al. 1998).

Festuca elatior (meadow fescue)

Meloidogyne naasi: Host (Radewald et al. 1970).

Festuca ovina (Sheep Fescue)

Criconemella xenoplax: In pots after senescence, Rf was 0.77 times initial population of 33/100 cm3 soil on cv. "Covar" (Zehr et al. 1990).

Festuca ovina var. diriuscula (Hard Fescue)

Criconemella xenoplax: In pots after senescence, Rf 0.16 times initial population of 33/100 cm3 soil on cv. "Covar" (Zehr et al. 1990).

Festuca pratensis (meadow fescue)

Meloidogyne chitwoodi: In pots, trace reproduction: very poor host (O'Bannon et al. 1984).
Meloidogyne naasi: N6-95 is a host for 4 US and 1 English population (Michell et al. 1973a). May cause failure of spring sowings, but fescues differ in host status (Cook and Yeates 1993). Host (Franklin 1965). Pratylenchus penetrans: Root populations exist (Bernard et al. 1998).

Festuca rubra (red fescue)

Meloidogyne chitwoodi: In pots, light reproduction: poor host (O'Bannon et al. 1984).
Meloidogyne naasi: Host; vars. commutate (Chewings fescue), Ranier, and Illahee are a hosts (Radewald et al. 1970).
Xiphinema americanum: In pots, 169 days after inoculation of Chewings with 72/100 g soil, the final population was 120/100 g soil (Miller 1980).

Festuca spp. (fescue, unspecified)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Hordeum bogdanii (wild barley)

Meloidogyne chitwoodi: Rf = 84.9 (Jensen and Griffin 1994).

Hordeum brevisubulatum (wild barley)

Meloidogyne chitwoodi: Rf = 22.9 (Jensen and Griffin 1994).

Hordeum californicum (wild barley)

Meloidogyne chitwoodi: f = 0.5 (Jensen and Griffin 1994).

Hordeum chilensis (wild barley)

Meloidogyne chitwoodi: Rf = 0.1 (Jensen and Griffin 1994).

Hordeum hystrix (wild barley)

Meloidogyne naasi: Host (Jensen et al. 1968).

Hordeum vulgare (barley)

Heterodera avenae: Causes stunting and chlorosis, branched root systems, and patchy growth, grain formation is inhibited (Kleynhans et al. 1996). Host in New Zealand (Knight et al. 1997)
Longidorus elongatus: Host (Norton et al. 1984). Causes damage (McGawley and Overstreet 1998).
Meloidogyne chitwoodi: In pots, tilleringwas was suppressed by M. chitwoodi but was affected less than wheat by inoculum densities of 0 to 2000/eggs 100 cm3 soil. Heads/plant or head dry weight did not correlate with inoculum level. M. chitwoodi inoculum prevented head set of Kombar spring barley. Root weights were reduced at all inoculum levels (Griffin 1992a). In pots, Boyer was a suitable host (Rf = 13.4) for Race 2 (alfalfa race) (Mojtahedi et al. 1988b). In pots, cvs. Advance, Boyer, Hesk, Klages, and Steptoe: high reproduction: good hosts; and cvs. Kamiak, Mal, Morex, Piroline, and Vanguard: very high reproduction: very good host (O'Bannon et al. 1984). At 500 and 5000 eggs/liter soil, Boyer total plant dry weight was significantly less than uninoculated controls. M. chitwoodi increased from 2 to 4 times on Boyer barley cultivars (Santo and O'Bannon 1981). In pots, Steptoe and Wocus 71 were maintenance hosts (Rf = 1.44 and 1.31), and Briggs is a poor host (Rf = 0.29) for race 1 (Ferris et al. 1993). In pots, 50 J2/100 cm3 soil reduced shoot weight by 25% at 25oC but not root and head weight in Steptoe; yields were not significantly different from uninoculated controls at 15 and 20oC (Umesh and Ferris 1994). Yields of spring barley were reduced by 3.5% for every 1000 J2/100g, up to a maximum 50% loss at 15000/100g; winter barley sustained less damage (Rivoal and Cook 1993). In pots, Rf of 1.1 on Boyer from inoculation of approximately 200/100 cm3 soil (Santo et al. 1980).
Meloidogyne hapla: In pots, not susceptible, and 0/20 inoculated plants were infected (Faulkner and McElroy 1964). In pots, cv. Wong is a host (Gaskin and Crittenden 1956). In pots, Rf of 0 on Boyer from inoculation of approximately 200/100 cm3 soil (Santo et al. 1980).
Meloidogyne naasi: Trail is a host for 4 US and 1 English population (Michell et al. 1973a). Damages spring barley (Franklin 1973). Where barley had been cropped continuously in California, losses amounted to 50 to 75% of the crop (Franklin 1973). Yields of spring barley were reduced by 3.5% for every 1000 J2/100 g soil up to a maximum 50% loss at 15,000 J2/100 g soil; winter sown barley damage was apparently lower (Rivoal and Cook 1993). Tennessee winter barley is a good host (Golden and Taylor 1967). enton and Trail are hosts; symptoms are worst in poorly drained areas (Jensen et al. 1968). Wocus is a host (Radewald et al 1970). Pratylenchus spp.: Causes severe damage (Kleynhans et al. 1996). Pratylenchus crenatus: At 500/g root in controls at harvest, yield correlated negatively with initial population (Rivoal and Cook 1993).
Pratylenchus neglectus: 150/100 cm3 soil at sowing decreased grain weight by 9% (Rivoal and Cook 1993). 150/100 cm3 soil significantly reduced root but not shoot or head weight at 20o C but not at 15o or 25o (Umesh and Ferris 1994).
Pratylenchus penetrans: Experimentally infected with P. penetrans (Jensen 1953).
Pratylenchus thornei: 4/100 cm3 soil decreased grain weight by 10%. (Rivoal and Cook 1993). In pots, 42 and 420/100 cm3 soil decreased ear weight by 26 and 45 %. (Rivoal and Cook 1993).
Xiphinema americanum: Host in commercial crops in California (Siddiqui et al 1973). 

Hordeum spp . (Barley)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Koeleria spp. (Hair grass)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Lolium multiflorum (Italian ryegrass)

Meloidogyne naasi: Host for 4 US and 1 English population (Michell et al. 1973a).
Pratylenchus neglectus: L. multiflorum is a host in California (Norton et al. 1984).
Pratylenchus penetrans: In pots, initial inoculum increased 50% (McDonald and Mai 1963).
Xiphinema americanum: In pots, 169 days after inoculation with 72/100 g soil, the final population was 24/100 g soil (Miller 1980).

Lolium perenne (perennial ryegrass)

Criconemella xenoplax: Did not suppress C. xenoplax when grown in association with peach trees (Whittington and Zehr 1992). In pots, after 90 days, Rf was 2.17 times initial population of 250/100 cm3 soil: host (Zehr et al. 1986).
Longidorus elongatus: Severely damaged (Hooper 1973). Induces galls (Griffiths and Robertson 1984).
Meloidogyne hapla: In pots, not susceptible, and 0/3 inoculated plants were infected (Faulkner and McElroy 1964).
Meloidogyne naasi: Host for 4 US and 1 English population (Michell et al. 1973a). Host (Franklin 1965, Radewald et al. 1970). Aldicarb applied at spring sowing of perennial ryegrass on field plots with 3800 J2/100 cm3 soil increased first year yields by 22%.(Cook and Yeates 1993). In pots, 20000 J2/100 cm3 soil reduced yields by 51% after 3 months, but 6000/100 cm3 had no effect in the field (Cook and Yeates 1993). Pratylenchus penetrans: In pots, initial inoculum increased 37% (McDonald and Mai 1963).

Lolium spp . (unspecified ryegrass)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)
Pratylenchus penetrans: In pots, initial populations of 33/100 g soil resulted in 50/g root and little necrosis on Oregon ryegrass after 3 months (Miller 1978).

Panicum capillare (common or old witchgrass)

Meloidogyne chitwoodi: In pots, light reproduction: poor host (O'Bannon et al. 1984).
Meloidogyne hapla: Non-host (Rf = 0) (Belair and Benoit 1996).

Pascopyrum smithii (Barton western wheatgrass) See also Agropyron compex.

Meloidogyne chitwoodi: Good host (Rf = 3.0) (Griffin et al. 1984).

Pennisetum glaucum (pearl millet)

Meloidogyne hapla: In pots, not susceptible, and 0/3 inoculated plants were infected (Faulkner and McElroy 1964).

Phalaris arundinacea (reed canary grass). EXTREMELY SERIOUS WEED; CHECK WITH YOUR STATE DEPARTMENT OF AGRICULTURE BEFORE PLANTING.

Meloidogyne hapla: In pots, not susceptible, and 0/3 inoculated plants were infected (Faulkner and McElroy 1964). Pratylenchus penetrans In pots, initial populations of 33/100 g soil resulted in 50/g root and very little necrosis after 3 months (Miller 1978).

Phalaris spp. (canary grasses)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972).
Tylenchorhynchus claytoni: Pest (Cook and Yeates 1993).
Paratrichorodus minor: Pest (Cook and Yeates 1993).

Phleum pratense (Timothy)

Meloidogyne hapla: In pots, Crummond was not susceptible, and 0/5 inoculated plants were infected (Faulkner and McEvoy 1964).
Meloidogyne naasi: Poor host (Cook and Yeates 1993).
Pratylenchus crenatus: Survived and reproduced (Bernard et al. 1998). Pratylenchus penetrans: In pots, initial populations of 33/100 g soil resulted in 50/ g root and very little necrosis after 3 months (Miller 1978). Experimentally infected with P. penetrans (Jensen 1953).
Pratylenchus neglectus: Host; moderate reproduction (Townshend and Anderson 1976).

Phleum spp . (Timothy)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Poa annua (annual bluegrass)

Meloidogyne chitwoodi: In pots, light reproduction: poor host (O'Bannon et al. 1984).
Meloidogyne naasi: Host for 4 US and 1 English population (Michell et al. 1973a). Host (Franklin 1965, Radewald et al. 1970, Radewald et al. 1966). Pratylenchus crenatus: Has caused damage as a member of mixed populations (Cook and Yeates 1993).

Poa pratensis (Kentucky bluegrass)

Criconemella xenoplax: In pots, after 90 days, Rf was 0.71 times initial population of 250/100 cm3 soil (Zehr et al. 1986).
Meloidogyne chitwoodi: In pots, trace reproduction: very poor host (O'Bannon et al. 1984).
Meloidogyne naasi: Filking is a host for 4 US and 1 English population (Michell et al. 1973a). Kentucky, Merion, Newport, and Park are hosts (Radewald et al. 1970). Host (Franklin 1965).
Tylenchorhynchus spp.: Pest (Cook and Yeates 1993).
Pratylenchus penetrans: Experimentally infected with P. penetrans (Jensen 1953).

Poa trivialis (rough bluegrass)

Meloidogyne naasi: Host for 4 US and 1 English population (Michell et al. 1973a). Host (Radewald et al. 1970).

Poa spp. . (Bluegrass, unspecified)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972) 

Polypogon spp. (beard-grass)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Pseudoegneria spicata (bluebunch wheatgrass). (Pseudoroegneria is a synonym for Elymus).

Meloidogyne chitwoodi: Nonhost (Rf = 0) (Griffin et al. 1984). Rf = 1.2 (Jensen and Griffin 1994).

Secale cereale (rye)

Criconemella xenoplax: In pots, after 90 days, Rf on Wre's Abruzzi was 0.84 from initial population of 250/100 cm3 soil (Zehr et al. 1986). Heterodera avenae: Causes stunting and chlorosis, branched root systems, and patchy growth, grain formation is inhibited (Kleynhans et al. 1996).
Longidorus elongatus: Host (Norton et al. 1984).
Meloidogyne chitwoodi: In pots, maintenance host (Rf = 1.07) for race 1 (Ferris et al. 1993).
Meloidogyne hapla: In pots, not susceptible, and 0/15 inoculated plants were infected (Faulkner and McElroy 1964). In pots, Imperial was a host (Gaskin and Crittenden 1956).
Meloidogyne naasi: Balboa is a host for 4 US and 1 English population (Michell et al. 1973a).
Paratrichodorus allius: Merced is a host (Norton et al. 1984). Paratrichodorus minor: Host (Hooper 1977).
Pratylenchus penetrans: In pots, initial populations of 33/100 g soil resulted in 220/g root and moderately severe necrosis after 3 months (Miller 1978). P. penetrans was more abundant where rye (Secale cereale) and crabgrass (Digitaria ischaemum and D. sanguinalis) had been grown than where buckwheat (Fagopyrum esculentum) and pigweed (Amaranthus retroflexus) had grown the previous season. Thereafter, P. penetrans remained high in crabgrass plots, moderately low in buckwheat plots, and fluctuated in rye and pigweed plots (Miller and Aherns 1969).
Pratylenchus neglectus: Host (Townshend and Anderson 1976).
Xiphinema bakeri: In pots, moderate damage and 285% population increase after 12 weeks on cv "Storm" (McElroy 1972).

Setaria lutescens (yellow or green foxtail)

Meloidogyne chitwoodi: In pots, trace reproduction: very poor host (O'Bannon et al. 1984). In pots, moderate reproduction: moderate host (O'Bannon et al. 1984).
Meloidogyne hapla: In pots, not susceptible, and 0/3 inoculated plants were infected (Faulkner and McElroy 1964).

Setaria viridis (green bristlegrass or foxtail)

Criconemella xenoplax: In pots, after 90 days, Rf was 0.07 times initial population of 250/100 cm3 soil: non-host (Zehr et al. 1986).
Meloidogyne hapla: In pots, Rf = 0 (Belair and Beniot 1996). 0 galls/g root after 50 days in pots inoculated with 3600 J2 (Townshend and Davidson 1962).

Setaria spp. (foxtail; German or Italian millet)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Sorghum bicolor (sorghum)

Criconemella xenoplax: On Pioneer 8333, root dry weight was reduced 20-27% by Tylenchorhynchus annulatus. The reduction was greater (35%, p = 0.001) when T. annulatus was combined with C. xenoplax, although C. xenoplax alone did not reduce root weight. DK 50 plants generally were larger than those of P8333 (Wenefrida et al. 1995, 1997).
Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)
Longidorus elongatus: Host (Norton et al. 1984).
Meloidogyne naasi: RS-610 is a host for Kansas but not California, Illinois, Kentucky, or English populations (Michell et al. 1973a).

Sorghum halpsense (Johnsongrass)

Criconemella xenoplax: In pots, after 90 days, Rf was 0.41 times initial population of 250/100 cm3 soil (Zehr et al. 1986).

SORGHUM SUDANENSE OR SUDAN X DRUMMONDII (Sudan grass)

Meloidogyne chitwoodi: In pots, Sudan grass (unspecified cultivar) was a is a poor host (Rf = 0.4) for Race 2 (alfalfa race) (Mojtahedi et al. 1988b). In pots, trace reproduction: very poor host (O'Bannon et al. 1984). Meloidogyne hapla: In pots, not susceptible, and 0/4 inoculated plants were infected (Faulkner and McElroy 1964).
Meloidogyne naasi: Trudan I is a non-host (Radewald et al. 1970). Paratrichodorus allius: Host (Norton et al. 1984).
Pratylenchus neglectus: Host in California (Siddiqui et al 1973). Pratylenchus penetrans: In pots, initial populations of 33/100 g soil resulted in 40/ g root and very severe necrosis after 3 months (Miller 1978). Sorghum spp. and their hybrids are possible rotation crops for suppression of P. penetrans in potato production (Cook and Yeates 1993). In pots, 23% increased of initial inoculum (McDonald and Mai 1963).
Pratylenchus thornei: Host in California (Siddiqui et al. 1973).
Xiphinema americanum: In pots, 169 days after inoculation of Sudanese with 72/100 g soil, the final population was 0/100 g soil (Miller 1980). Associated with commercial crops in California (Siddiqui et al. 1973).

Spartina spp . (Cordgrass)

Trichodorus obscurus: Host (Norton et al. 1984).

Thinopyrum intermedium See Agropyron complex.
Triticum aestivum (bread wheat); T. turgidum: (durum group)

Criconemella xenoplax: Populations were lower in Stacey plots than in non- fumigated peach plots after three years (peach is a good host) (Nyczepir and Bertrand 1994). In pots, after 90 days, Rf on Coker 6815 was 0.25 from initial population of 250/100 cm3 soil (Zehr et al. 1986). Heterodera avenae Causes stunting and chlorosis, branched root systems, and patchy growth, grain formation is inhibited (Kleynhans et al. 1996). Host in New Zealand (Knight et al. 1997)
Longidorus elongatus: Host (Norton et al. 1984).
Meloidogyne chitwoodi: In pots, Nugaines was a maintenance host for race 1. In field trials, population levels on Russet Burbank were significantly higher following wheat cv. Fieldwin and Austrian winter peas and fallow than following other crops. (Ferris et al. 1993). In pots, tillering, heads/plant, head length, and dry weight were negatively correlated with inoculum level (from 0 to 2000/100 eggs cm3 soil). The greatest plant height reduction was at 2000/100 cm3 soil. Head development was reduced on spring cultivars Fremont, Twin, Borah, and Fielder. Winter cultivars Nugaines and Wanser were better hosts for the Utah population than were Manning, Dusty, or Daws (Griffin 1992a.) In pots, Fielder (spring) was a suitable host (Rf = 36.8) for Race 2 (alfalfa race). Nugaines (winter) (Rf = 17.3) is a is a suitable host for Race 2 (alfalfa race) (Mojtahedi et al. 1988b). In pots, the relationship between top dry weight and initial nematode density suggests a tolerance limit for Nugaines wheat of between 3 and 18 eggs/100 cm3 soil at planting; tolerance in February was greater than tolerance in April. Nugaines withstood up to 900/100 cm3 soil with no effect on yield. In microplots, yield of Fielder spring wheat was decreased by 41% and 73% by 75 and 900 eggs/100 cm3 soil, respectively. M. chitwoodi reproduced on cvs. Fielder, Fieldwin, Hyslop, Gaines, and Nugaines, but fewer eggs were recovered from Gaines and Nugaines, confirming that Nugaines is a poor host compared to Fielder (Nyczepir et al. 1984). In pots, spring wheat cvs. Borah, Dirkwin, Fielder, Fieldwin, Owens, Sawtell, Sterling, and Twin: very high reproduction: very good hosts. Cv. Twin: high reproduction: good host. Winter wheat cvs. Faro: moderate reproduction, moderate host. Cv. Barbee, Hylsop, Luke, Moro, Neeley, Palouse, Tyee, and Wanser: high reproduction, good hosts. Cvs. Nugaines, Prodax, and Stephens: very high reproduction, very good hosts (O'Bannon et al. 1984). At 500 and 5000 eggs/liter soil, Wanser wheat total plant dry weight weighed significantly less than uninoculated controls. Roots but not top growth of Prodax and Nugaines weighed less than uninoculated controls. M. chitwoodi increased from 11 to 65 times on wheat cultivars (Santo and O'Bannon 1981). Meloidogyne hapla Cvs. Fielder, Fieldwin, Hyslop, Gaines, and Nugaines are not hosts (Nyczepir et al. 1984). In pots, Omar winter wheat and Federation, Marfed, and Pilcraw spring wheat were not susceptible, and no plants inoculated were infected (Faulkner and McElroy 1964). In pots, cvs. "Thorne", "Nured", and "Seneca" were not hosts (Gaskin and Crittenden 1956).
Meloidogyne naasi: Damages spring wheat (Franklin 1973). Pawnee is a host for 4 US and 1 English population (Michell et al. 1973a). amona 50 is a host (Radewald et al. 1970).
Paratrichodorus allius: var. vulgare is a host (Norton et al. 1984).
Trichodorus obscurus: Host (Norton et al. 1984).
Pratylenchus spp.: Causes severe damage (Kleynhans et al. 1996). Pratylenchus crenatus: Associated with yellowing and stunting of wheat (Kleynhans et al. 1996).
Pratylenchus neglectus: Relatively weak pathogen on Stephens wheat (Mojtahedi and Santo 1992). Host in California (Siddiqui et al 1973). Associated with yellowed and stunted patches of plants in wheat fields during spring in southrn Ontario, Canada. (Townshend and Anderson 1976).
Pratylenchus thornei: 0 to 100/100 cm3 soil (Rivoal and Cook 1993). In pots, 667/100 cm3 soil caused stunting and chlorosis on "Stephens". 67/100 cm3 caused no noticeable damage (Mojtahedi et al. 1988). Associated with wheat exhibiting unthrifty patches and stunted and chlorotic growth, sometimes in low spots, and in Madsen wheat with intermittent yield problems, in SE Washington (W. T. Cobb, pers. comm., 1997). In Mexico, on wheat cultivars Tobari and Inia, 42, 420, and 4,200 P. thornei/100 cc soil reduced heat weight 26, 45, and 34%, respectively, after 60 days. Yields of cultivars Inia, Tobari, Azteca, Norteno, Lerma Rojo, and Siete Cerros on fumigated soils were from 19 to 30% higher than yields on soils with 173-229 P. thornei/100 cm3 soil (Van Gundy et al. 1974). Probably reduces yield in wheat grown during relatively dry seasons and in soil with a relatively high nematode population at seeding (Baxter and Blake 1968). Serious parasite in Utah. Severe stunting follows attack of young, succulent roots. Heads bore substandard grain numbers (Thorne 1961).
Xiphinema americanum: Associated with commercial crops in California (Siddiqui et al. 1973). top of the page

Vulpia spp . (Annual fescue)

Heterodera avenae: Host; can maintain populations between cereal crops (Williams and Siddiqi 1972)

Zea mays (corn, maize)

Heterodera avenae: May be severely damaged by invading J2, but the life cycle is not completed. Heavy infestations result in root death, and new roots are subsequently invaded (Dropkin 1980). May be damaged when heavily infested (Kleynhans et al 1996). Corn is sometimes attacked, but it is not usually a good host (Williams and Siddiqi 1972).
Longidorus elongatus: Rugosum is a host (Norton et al. 1984). Meloidogyne spp.: Species other than M. hapla usually decrease under corn (Baldwin and Barker 1970).
Meloidogyne chitwoodi: In pots, Idahybrid 303, Northrup King 497, and Pioneer 3232 were suitable hosts (Rf = 12.1, 6.9, and 8.6) for Race 2 (alfalfa race) (Mojtahedi et al. 1988b). Idahybrid 303 and Northrup King 497 were suitable hosts (Rf = 6.5 and 2.2) for for Race 1 (non-alfalfa race) (Mojtahedi et al. 1988b). In pots, cv. Northrup King 497: trace reproduction, very poor host. Cvs Cenex 2119, Funks G4574, JX 122A, JX 1153, and Northrup King PX 46: moderate reproduction, moderate hosts. Cvs. Funks G-4444 MF, Idahybrid 216, and Northrup King 589: high reproduction, good hosts (O'Bannon et al. 1984). At 500 and 5000 eggs/liter soil, PX 46 total plant dry weight was significantly less than controls; Jubilee root weight but not dry weight dry weight was not reduced. M. chitwoodi reproduced but did not increase on PX 46 and Jubilee (Santo and O'Bannon 1981). In pots, Rf of 1.9 on PX 46 from inoculation of approximately 200/100 cm3 soil (Santo et al. 1980).
Meloidogyne hapla: Does not reproduce on corn (Baldwin and Barker 1970, Sasser 1966). In pots, Dwarf, Medium Hat 354, and Nestam 101 were not susceptible, and no inoculated plants were infected (Faulkner and McElroy 1964). In pots, Rf of 0 on PX 46 from inoculation of approximately 200/100 cm3 soil (Santo et al. 1980).
Meloidogyne naasi: Non-host (Radewald et al. 1970).
Paratrichodorus allius: Host (Norton et al. 1984).
Pratylenchus spp.: Moderately damaged (Kleynhans et al. 1996). Pratylenchus crenatus: Recorded (Kleynhans et al. 1996).
Pratylenchus neglectus: Recorded (Kleynhans et al. 1996). Host in California (Siddiqui et al 1973).
Pratylenchus penetrans: In pots, 25/100 cm3 soil significantly reduced root growth at 20 and 24 but not 16 and 28o C and top growth at 20o C only; stem diameter was not reduced (Dickerson et al. 1964). In pots, initial populations of 33/100 g soil resulted in 70/g root and little necrosis on "Butter and Eggs" after 3 months (Miller 1978).
Pratylenchus thornei: Associated with corn in Wisconsin (Norton et al. 1984). Serious parasite in limited areas of Salt Lake County, Utah; associated with severe smut infestation (Thorne 1961).
Xiphinema americanum: On Funk's G4444 Hybrid, X. americanum populations reached maxima of about 15 to 55 from early August through early September and minima of about 1 to 4 from April through July. Densities were greater in no-till ridge plots. Densities in till-plant plots were greater than those in fall-plowed plots Thomas 1978). Cv. A619Ht X A632Ht is a host (Norton and Edwards 1988). In pots, 169 days after inoculation of an unspecified cultivar with 72/100 g soil, the final population was 0/100 g soil (Miller 1980).

LITERATURE CITED

Acosta, N., and Malek, R. B. 1979. Influence of temperature on population development of eight species of Pratylenchus on soybean. Journal of Nematology 11:229-232.

Barker, K. R., and Olthof, T. H. A. 1976. Relationships between nematode population densities and crop responses. Annual Review of Phytopathology 14: 327-353.

Baxter, R. I., and Blake, C. D. 1968. Pratylenchus thornei - a cause of root necrosis in wheat. Nematologica 14:351-361.

Belair, G., and Benoit, D. L. 1996. Host suitability of 32 common weeds to Meloidogyne hapla in organic soils of southwestern Quebec. Journal of Nematology Supplement 28:643-647.

Bendixen, L. E., Reynolds, D. A., and Reidel, R. M. 1979. An annotated bibliography of weeds as reservoirs for organisms affecting crops. I. Nematodes. Ohio Agriculture Research and Development Center, U. S. 250 and Ohio 83 South, Wooster, OH.

Bernard, E. C., Gwinn, K. D., and Griffin, G. D. 1998. Forage grasses. pp. 427-454 In: Plant and Nematode Interactions, Barker, K. R., Pederson, G. A., and Windham, G L. American Society of Agronomy, Inc, Madison, Wisconsin. 771 pp.

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