Meloidogyne exigua Goeldi, 1887
Meloidogyne exigua was the first root-knot species described under
this genus name. It was described by GÃƒÂ¶ldi
(sometimes Goeldi) in 1887 having first been
reported by Jobert in 1878 on coffee in Brazil.
Some history....(adapted from an article by
Luiz Carlos Ferraz in Nematology Newsletter 54(2):8.)
Emil August Goeldi (1859-1917), a naturalist from Switzerland,
was invited by the government of Brazil to investigate the decline of coffee
trees growing in the
Local coffee producers had alerted the Emperor to their
problem several years earlier and ClÃƒÂ©ment Jobert, a French researcher, had
already published (1878) a brief note speculating that the causal agent was a
nematode of the genus
In 1897, Goeldi p
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Coffee-producing areas of Central and South America and southern India,
China, and some southern European countries (Elling, 2013).
Meloidogyne exigua is present in 22% of the coffee plantations and
95% of the districts in southern Minas Gerais State in Brazil; that region
accounts for nearly half of Brazil's coffee production (Elling, 2013).
C-rated pests in California.
Feeding site establishment and
development typical of genus.
Coffee, banana, watermelon, pepper, tomato, onion, sugarcane, citrus, rice,
rubber tree, and weeds (e.g., Taraxacum officinale, Amaranthus
deflexus, and Poinsetta heterophylla).
All themain coffee cultivars grown are susceptible to M. exigua
nematode and germplasm screens have failed to identify resistance in Coffea
arabica (Elling, 2013).
Feeding causes yellowing of leaves, leaf fall, destruction of root hairs and
rootlets, root lesions, small root galls, vascular disruption, and secondary
invasion. Yields of non-infested plants may be twice as high as
those infested with M. exigua (Lordello, 1986).
Coffee yield losses estimated at 10-20% in Costa Rica and 45% in Brazil.
Root necrosis and defoliation are greater when roots are infected by both
M. exigua and Rhizoctonia solani than by either organism alone.
Meloidogyne exigua typically induces round galls on coffee roots with
egg masses within the galls (Humphreys=Pereira et al., 2014).
Treatment of seedbeds with nematicides
is effective; however, use of
nematicides on established coffee plants is not feasible due to
Produce coffee seedlings in nurseries where soil has been disinfested.
In Minas Gerais, Brazil, the best time to implement chemical control
measures against M. exigua is November, which coincides with renewed
plant root growth, a high level of lipid reservesin J2, high nematode
population density, and high infectivity (Elling, 2013).
Host Plant Resistance, Non-hosts
Although there is no known resistance in Coffea arabica,
rootstocks are available, but yield is lower. Coffeae canephora cv
robusta is highly resistant to M. exigua.
One year fallow period recommended before replanting an infested coffee
plantation in Brazil.
Elling, A.A. 2013. Major Emerging Problems with Minor Meloidogyne Species.
Goeldi, E.A. 1887. Relatorio sobre a molestia do cafeeiro na provincia do Rio
de Janeiro. Archivos do Museo Nacional 8:7-123 (1892)
Humphreys-Pereira, D.A., Flores-Chavez, L., Gomez, M., Salazar, L.
Gomez-Alpizar, L.E., Elling, A.A. 2014. Meloidogyne lopezi n.sp.
(Nematode: Meloidogynidae, a new root-knot nematodeÃ¯Â¿Â½.. Nematology 16:643-661.
Lordello, L.G.E. 1986 Plant-parasitic nematodes that attack coffee. Pp
33-41 in Anon. Plant-parasitic nematodes of bananas, citrus, coffee,
grapes and tobacco. Union Carbide Corp.