Rev 03/16/2021
Synonyms: None.
Adults are 0.75-1.0 mm long.
Female:
Stylet knobs have two anteriorly projecting processes. Esophogeal glands overlap intestine dorsally; esophageal glands with 6 nuclei, 4 in the dorsal gland and one in each of the subventral glands.. Excretory pore behind level of esophago-intestinal valve. Ovaries are outstretched and spermatheca is absent. Intestine overlaps rectum, extending partly into the tail. Tail is rounded, with 16-22 annules. Lateral field, represented by only 1 indistinct incisure. Cephalic region offset, usually with 3 annules, but a fourth annule is often seen on one side of the cephalic region due to subdivision of one annule. The basal annule of the lip region has 10-15 longitudinal lines. Basal plate with 6 arms. Hemizonid 2-5 annules posterior to excretory pore. Hemizonian not seen. Anterior phasmid is 38% from the anterior end on the right side; posterior phasmid at 81% from the anterior end on the left side. The diovarial reproductive system is fully developed after the fourth molt, and occupies about 61% of the body length. Eggs are laid individually and have a stalk up to 15μm long which can be used as a diagnostic character.
Stylet knobs have two anteriorly projecting processes.
Esophogeal glands overlap intestine dorsally; esophageal glands with 6 nuclei, 4 in the dorsal gland and one in each of the subventral glands..
Excretory pore behind level of esophago-intestinal valve.
Ovaries are outstretched and spermatheca is absent.
Intestine overlaps rectum, extending partly into the tail.
Tail is rounded, with 16-22 annules.
Lateral field, represented by only 1 indistinct incisure.
Cephalic region offset, usually with 3 annules, but a fourth annule is often seen on one side of the cephalic region due to subdivision of one annule. The basal annule of the lip region has 10-15 longitudinal lines. Basal plate with 6 arms.
Hemizonid 2-5 annules posterior to excretory pore.
Hemizonian not seen.
Anterior phasmid is 38% from the anterior end on the right side; posterior phasmid at 81% from the anterior end on the left side.
The diovarial reproductive system is fully developed after the fourth molt, and occupies about 61% of the body length.
Eggs are laid individually and have a stalk up to 15μm long which can be used as a diagnostic character.
Male:
Extremely rare. Body shape and general morphology similar to female except for sexual dimorphism and the following differences: Cephalic region with 3 or 4 annules with 7-8 longitudinal lines on basal annule. Excretory pore anterior or posterior to esophago-intestinal valve. Hemizonid 2-8 annules posterior to excretory pore and hemizonion 10 annules posterior to hemizonid. No longitudinal incisure on body Gubernaculum trough like, with distinct titillae Spicules 37-53μm long, slightly arcuate with a very thin velum observed only when spicules are extended. Telamon distinct, lying between spicules. Bursa begins at about anterior end of the spicules and extends around the tip of the tail.
Extremely rare.
Body shape and general morphology similar to female except for sexual dimorphism and the following differences:
Cephalic region with 3 or 4 annules with 7-8 longitudinal lines on basal annule.
Excretory pore anterior or posterior to esophago-intestinal valve.
Hemizonid 2-8 annules posterior to excretory pore and hemizonion 10 annules posterior to hemizonid.
No longitudinal incisure on body
Gubernaculum trough like, with distinct titillae
Spicules 37-53μm long, slightly arcuate with a very thin velum observed only when spicules are extended. Telamon distinct, lying between spicules. Bursa begins at about anterior end of the spicules and extends around the tip of the tail.
[Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 6, No. 81 (1976)]
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Hoplolaimus columbus has been reported from several different countries around the world, including infestations in Pakistan, India, and the United States. In the U.S., H. columbus is limited mainly to the southeastern part of the country, reported in North Carolina, South Carolina, Georgia, Alabama, and Louisiana. It is reported most frequently from the coastal plains of Georgia, North Carolina, and South Carolina. 50% of the cotton acreage of South Carolina is infested and, of that acreage, 38% is above threshold levels (greater than 500 per pint of soil). In sandy loam soils, on favorable hosts, it often replaces Meloidogyne incognita as the predominant species.
While the reports from Alabama and Louisiana are isolated, many experts anticipate H. columbus will continue to spread throughout the cotton belt.
Sandy and sandy loam soils seem to be the preferred habitat.
[Source: www.cottonexperts.com, Manual of Agricultural Nematology]
Hoplolaimus columbus causes significant damage to cotton and soybeans where it occurs in the southeastern US.
Hoplolaimus columbus in cotton roots
Ecto- and endoparasitic on soybeans and cotton; causes discolored cortical cells in root maturation zone.
Does not penetrate endodermis in cotton, but does in some soybean varieties where it penetrates endodermis, pericycle, and phloem.
On cotton it feeds as a migratory endoparasite, penetrating the cortex but not the endodermis. H. columbus often feeds on the root tips of young cotton plants, altering root growth patterns.
[Source: “Plant Parasitic Nematodes Attacking Cotton in the United States”]
The two most important hosts in the United States are cotton and soybeans. Corn and wheat are also hosts, but the nematode is not yet reported from areas of intensive production of these crops.
Watermelons, cucumbers, okra, and cantaloupe are all poor hosts and tolerant of the nematode. In these cases the nematodes will survive on their roots, but yield is not affected.
Weed hosts include henbit, nutsedge, cowpeas, crimson clover, pigweed, sicklepod, and showy crotolaria.
Other hosts include sugarcane, bananas, lima beans, snap beans, bermudagrass, zoysia, millet, and St. Augustine grass.
[Source: http://pubs.caes.uga.edu, Plant Parasitic Nematodes of Subtropical and Tropical Agriculture]
Ecophysiological Parameters:
Reproduction is by parthenogenesis and males are extremely rare.
The life cycle on cotton and soybeans is 45-49 days.
H. columbus females deposit eggs individually, not in masses. However, 20-50 eggs may be deposited in a local area.
The nematode has a high capacity to survive adverse conditions and a very high overwintering rate. It can tolerate extremely high desiccation and osmotic stress.
All motile stages are infective.
H. columbus is reported to survive in dry soil for up to five years
[Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 6, No. 81 (1976) and H. Ferris.]
Lewis, Smith, and Powell (1974) demonstrated pathogenicity on soybean and cotton. Astudillo & Birchfield (1980) observed that H. columbus was present throughout the roots of sugarcane, damaged parenchyma, caused cell necrosis, and resulted in coarse, depleted root systems. However, root and shoot weights and leaf lengths were not affected.
Maximum potential yield suppressions of 18% on cotton and 48% on soybean were predicted by danage functions devekioed for H. columbus (Noe, 1993).
Infected soybeans are dwarfed, wilted, chlorotic and/or bear only a few pods.
In cotton, the nematode feeds on the root tips of young plants, altering root growth patterns. The taproot maybe stunted and secondary branching may increase in the upper four inches of soil. This restricts the uptake of water and nutrients causing stunting and mild chlorosis. Affected cotton plants show symptoms of nutrient deficiency, including purple leaves, shedding of squares, and small bolls.
The damage to cotton roots makes the plant very susceptible to Rhizoctonia solani.
The nematode also may cause lesions on roots and discolor cortical cells in the root maturation zone.
Populations increase to levels as high as 4,000 per 100cc soil.
[Nematode Pests of Crops]
Cultural Practices:
Crop rotations with non-host crops or non-host cover crops is effective.
Since there are many weed hosts and the nematode can survive in dry soil for several years, fallowing a field to reduce the pest may be ineffective.
A shallow hardpan often restricts roots to upper 6 inches of soil and reduces plant tolerance. Subsoiling and fumigation increases yield dramatically (Bird et al., 1974). Subsoiling and destruction of restrictive soil layers allows greater access to water and nutrients and can offset nematode damage.
Host Plant Resistance, Non-hosts and Crop Rotation alternatives:
Nematicides:
Fumigants are effective and can result in a 5-fold increase in yield of cotton. Nematicides such as Telone have been most effective way to decrease population levels.
[Source: Plant Nematodes and Their Control]
CIH Descriptions of Plant-parasitic Nematodes, Set 6, No. 81 (1976)
Bhatti et al, Nematode Pests of Crops, 1992. CBS Publishers, Bhola Nath Nagar, Shahdara
Decker, Heinz. Plant Nematodes and Their Control, 1981. Loglos Publishers, Moscow
Luc, Michel et al., Plant Parasitic Nematodes in Subtropical and Tropical Agriculture, Second Edition. 2005. CABI Publishing, Wallingford, UK
Noe, J.P. 1993.Damage Functions and Population Changes of Hoplolaimus columbus on Cotton and Soybean. J. Nematology 25:440-445.
http://apsnet.org/pd/pdfs/2003/1208-01F.pdf. “Plant Parasitic Nematodes Attacking Cotton in the United States”, by Koenning et al. Visited Friday, November 26, 2005
http://plpnemweb.ucdavis.edu/nemaplex/nemaplex.htm. Nemaplex. Hoplolaimus columbus. Visited Monday, November 21, 2005
http://www.cottonexperts.com/=file:Industry%20News/1060992211903010d012553d26063229/file. Nematodes: A belt-wide Threat. Visited Friday, November 26, 2005
http://pubs.caes.uga.edu/caespubs/pubcd/B904.htm. Plant Susceptibility to Major Nematodes in Georgia. Visited Friday, November 26, 2005.