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RESULTS AND DISCUSSION
Emergence of juveniles from the egg masses immersed in leaf and root extracts of Ruta graveolens, either alone or
combined, was significantly suppressed compared to the water control in all the four Meloidogyne species (Table 1).
Leaf extract was always more effective than root extract and resulted statistically more suppressive also than
fenamiphos solution. No synergic effect was derived from the combination of the two extracts, as final hatch was higher
than in leaf extract alone. Egg masses immersed in root leachates gave a final hatch similar to control.
The ultimate egg hatch of H. schachtii cysts incubated in single root and leaf extracts was significantly less than in 3
mM zinc sulphate and fenamiphos (Fig. 1). Suppressivity of the extracts decreased when in combination, as no
difference there was in final hatch compared to the control. There was no difference between leaf and root extracts,
whereas their combination resulted in a significantly higher egg hatch. As found in Meloidogyne species, no significant
emergence reduction was found for the root leachates.
In conclusion, the experiment evidenciated the nematicidal properties of rue extracts. The nematicidal compounds
seemed to be present in all the plant tissues, but especially in leaves. A possible antagonistic effect of leaf and root
extracts emerged from the results, that could be attributable to a negative interaction of the active principles responsible
for the suppressive effect. The absence of a nematicidal effect in root leachates indicated that nematicidal compounds
are present only in plant tissues, but not released into the soil.
LITERATURE CITED
Aliotta, G., and G. Cafiero, (1994). Potential allelochemicals from Ruta graveolens L. and their action on radish seeds.
Journal of Chemical Ecology 20 (11): 2761-2775.
Clarke A.J. and A.M. Shepherd, (1966). Inorganic ions and the hatching of Heterodera spp. Annals of Applied
Biology 58: 49–508.
Grainge M. and S. Ahmed, (1988). Handbook of Plants with Pest-Control Properties. (J. Wiley and Sons eds.) New
York, pp. 238-248.
Hussey R.S. and K.R. Barker, (1973). A comparison of methods of collecting inocula of Meloidogyne spp. including a
new technique. Plant Disease Reporter 57: 1025-1028.
Landolt, P. J.,R. W. Hofstetter and L. L. Biddick , (1999). Plant essential oils as arrestants and repellents for
neonate larvae of the codling moth (Lepidoptera: Tortricidae). Environmental Entomology 28 (6): 954-960.
Oliva, A. and E. Lahoz, (1999). Fungistatic activity of Ruta graveolens extract and its allelochemicals. Journal of
Chemical Ecology 25 (3): 519-526.
Seinhorst J.W. and H. Den Ouden (1966). An improvement of Bijloo’s method for determining the egg content of
Heterodera cysts. Nematologica (12): 170-171.
Table 1. Effect of root and leaf extracts and root leachates of rue (Ruta graveolens L.) on the total percent cumulative
hatch of four different Meloidogyne species.
Treatments
70
Meloidogyne species
M. arenaria M. hapla M. incognita M. javanica
Leaf extract 12 6 12 3
Root extract 59 43 61 23
Root and leaf extract 20 21 49 21
Root leachates 83 91 80 89
Fenamiphos 38 47 29 31
Distilled water 81 87 75 92
L.S.D. 0.05 11 12 15 15
L.S.D. 0.01 15 15 20 20
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