EFFECTS OF MEAL AND SAPONINS OF ASTER CAUCASICUS AND OF A. SEDIFOLIUS ON THE CONTROL OF NEMATODES

Root-knot nematodes (Meloidogyne spp.) are a severe economic constraint of
vegetable and industrial crops in the Mediterranean region. The control of these
nematodes is necessary to maintain crop yield and quality at economic levels. The
use of synthetic pesticides is expensive and polluting. As an alternative, nematodes
can be managed by biopesticides. In this study, we evaluated the nematicidal activity
of leaf and root meals from Aster caucasicus and A. sedifolius and of the saponins
extracted from A. sedifolius on M. incognita and the potato cyst nematode Globodera
rostochiensis. Leaf and root meals did not affect root gall index in tomatoes
inoculated with M. incognita, while the reproduction of the nematode was reduced
by about 97% with 0.5 and 1 g/100 cm3 soil of meals from leaves and roots of A.
sedifolius. The effect of A. caucasicus was restricted to leaf meal: the reduction of the
nematode eggs per tomato root was 82.3 and 92.7% at 0.5 and 1 g/100 cm3 soil,
respectively. When the soil was treated with purified saponins of A. sedifolius at
rates from 1.19 to 4.75 mg/100 cm3 soil, the reproduction of the nematode was not
affected. Moreover, saponins of A. sedifolius did not show any effect on the viability
of second stage juveniles of M. incognita as well as of G. rostochiensis.