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When vegetables are cultivated in the
same area, with no control measures in
place, they frequently do not survive the
intense outbreaks of different root knot
nematode strains (Meloidogyne spp.).
Losses could amount to 100%, depending
on the degree of infestation of the area, on
the nematode strain, on cultivar and envi-
ronmental conditions. Currently, there are
three strains of this soil pathogen group
considered to be the most harmful to veg-
etables (Meloidogyne incognita, M. javan-
ica e M. arenaria). However, there is one
strain that has been causing serious dam-
age to vegetables, and it is phytopatholo-
gy’s biggest concern. The strain in ques-
tion is known as Meloidogyne enterelobii,
of the root knot nematode family, for
which there is no resistance gene in the
currently grown vegetables.
According to agronomist Jadir Borges
Pinheiro, researcher at Embrapa Vegeta-
bles, the strain was first detected in Bra-
zil in 2001, in guava plants, in the states
of Pernambuco and Bahia, causing much
damage to the commercial crops of this
fruit. After reports of outbreaks in the
Brazilian Northeast, in 2006 this nem-
atode was detected in vegetables in the
State of São Paulo, affecting cultivars re-
sistant, up to that time, to other strains
of root knot nematodes prevalent in the
Country. “Besides spreading rapidly, M.
enterolobii infects a big number of host
plants, including a variety of ornamental
plants, tobacco and soybean”, he says.
Pinheiro reiterates that the strain is now
present in most states, but information on
how it affects infected vegetables, intend-
ed to reduce future problems, is scarcely
available. “One of the big challenges, along
with plant enhancement efforts, consists
in the development of resistant cultivars
for managing this nematode”, he explains.
At Embrapa Vegetables, in Brasília, artificial
inoculation is carried out in a controlled
manner in tomato varieties and other veg-
etable species, with the aim to identify re-
sistance sources. At the end, the idea is to
come up with a tomato cultivar, either in-
dustrial or table tomato, that could be pro-
duced in infected areas, as is the case in
the interior of São Paulo.
“Once we find the resistance gene that
contemplates this specific species, the
farmers can plant it and put up with this
problem, once nematodes cannot be erad-
icated”, the nematologist says. In his view,
the use of resistant cultivars is advanta-
geous in that it does not require any ad-
ditional technology and, as a result, has a
low cost and hardly any impact upon the
environment. “The nematode resistance
sources identified so far have not been
thoroughly studied, if compared to the ex-
isting genetic diversity, especially in vege-
tables”, he explains.
Besides the development of resistant
cultivars, the specialist points out that the
challenges also include research on other
plants that are antagonists of the Meloido-
gyne, the succession or crop rotation study
in the management of M. enterolobii and
other practices and technologies that could
be used in infected areas, for correct and
sustainable management of these parasites.
“In Brazil, the problems caused by nema-
todes in vegetables are all the more serious
because of the cultivation of huge areas and
intensive vegetable cultivation throughout
the year, few professional trained in nem-
atology techniques, lack of strict quarantine
legislation and because of the shortage of
resistant vegetable cultivars”, he ascertains.
(In)visible problem
Meloidogyneenterolobii challengesnematologywithintheolericulture
contextandpromptsthepursuitofcultivarsresistanttothestrain
