TABLE CONTENTS

Selection of Virulent Populations of Meloidogyne incognita in Pepper
Ros, C. (1), A. Lacasa (1), M.C. Martínez (1), A. Cano (2), M.A. Díez (3), J.A. López (3),
L. Robertson (3) & A. Bello (3)
(1) Biotecnología y Protección de Cultivos, IMIDA, C/Mayor s/n 30150 La Alberca Murcia (Spain); (2) SSVV.
Consejería de Agricultura y Agua. /Mayor s/n 30150 La Alberca Murcia (Spain); (3) Agroecología, Centro de
Ciencias Mediambientales, CSIC, C/ Serrano 115 28006 Madrid (Spain)
In the Southeast of Spain, Meloidogyne incognita is widely distributed in greenhouses in the
Region of Murcia where pepper has been a monocrop for more than 20 years. The prohibition
of methyl bromide as a soil disinfectant has lead to the use of resistant root stocks in the
control of nematodes. In a greenhouse contaminated with M.incognita, resistant root stocks
were used in soil which had not been disinfected during a 5 year period, comparing the
nodulation index and percentage of plants infested in soil disinfected with methyl bromide
and non disinfected soil were susceptible plants without grafting were grown. In the second
year there was a selection of populations which parasitized the resistant root stock cv Atlante
(5.6 and 100%) and there was no difference in the susceptible plants (7.3 and 100%). After
two more years of using the same rootstock another three resistant rootstocks were tested in
the 4th year with these virulent populations. The three new rootstocks were not as affected
(C19: 0.3 and 13.3%; DRO 8801: 0.3 and 13.3%; Snooker: 10 and 53.3%). Following a
further year using these roost stocks a new selection of the populations was observed (C19:
2.4 and 76.7%; Snooker: 3.7 and 80.0%). It is suspected that there exist different sources of
resistance for this nematode in commercial root stocks.
Host Plant Resistance for Management of Root-knot Nematodes in Maize
Ngobeni, L. (1), H. Fourie (1), A.H. Mc Donald (1) & P.W. Mashela (2)
(1) Plant Protection Division, Nematology Unit, ARC – Grain Crops Institute, Private Bag X1251,
Potchefstroom, 2520, South Africa; (2) Department of Entomology and Nematology, University of Limpopo,
Turfloop Campus, Private Bag X1106, Sovenga, 0727 South Africa
Identification and validation of root-knot nematode resistance in maize germplasm became a
crucial element for cost-effective control of these parasites over the long term. Thirty local
commercial cultivars and open-pollinated varieties (OPV) of maize were screened for
resistance to M. javanica and M. incognita race 2 in two separate greenhouse trials. Each
seedling was inoculated with ±10 000 root-knot nematode eggs and second-stage juveniles
(J2). Nematode evaluations were done after 56 days. Twenty-one of the genotypes
maintained RF-values ≤ 1 for M. javanica and 18 did not support reproduction of M.
incognita race 2. These genotypes could therefore be classified as poor hosts to the respective
root-knot nematode populations. Verification of such resistance was done in two separate
microplot trials to determine the effect of initial inoculation densities (Pi ± 0 to 40 000) of M.
incognita race 2 and M. javanica, respectively. The M. incognita race-2 trial included
PAN6549 (susceptible standard OPV), QS-Ob (resistant standard OPV) and MP712W
(acquired resistant standard inbred line). The former two as well as AFG4410 (susceptible
standard OPV) were used for the M. javanica trial. QS-Ob and MP712 supported
significantly lower M. javanica and M. incognita race 2 numbers in both trials than the
respective susceptible standard genotypes. Strong non-linear relationships were shown for
both resistant and susceptible genotypes with regard to the RF values and number of eggs and
J2 per root system. Results from this study demonstrate the benefits that poor-host status of
5 th International Congress of Nematology, 2008 238