Abstract:
The response of different crops to a mixed population
of root-knot nematodes, Meloidogyne javanica and M. incognita
and their potential as suppressants in sequential cropping systems was
evaluated in greenhouse and field experiments. Crops rated as resistant
were five maize cultivars, four sorghum cultivars, two millet varieties,
guwar and two pigeonpea cultivars which had galling indices ranging between
1.4-3.6. cowpea cv. K80 was rated as moderately resistant with a galling
index of 4 while greengram and cowpea cv. KKI were rated as susceptible
with galling indices ranging from 5.6 to 7.4. Four crops namely sweetcorn,
babycorn, maize cv. Pioneer (Ph3253) and guwar were selected after the
greenhouse tests for field trials, based on their poor host status to
root-knot nematodes as well as relative acceptability to vegetable growers.
These crops were then incorporated into a rotation program with okra.
Initial and final J2 numbers in the field were determined before
planting and at the end of the season, respectively. Okra was then sown
in the plots previously grown with the selected nematode suppressive crops
and the nematode numbers determined mid and end of the season. A 44 and
21% decline in nematode numbers was recorded in plots under guwar or sweetcorn
and babycorn, respectively. In contrast, a 441% increase in nematode numbers
was recorded in plots under continuous crop of okra. The galling index
on a crop of okra that followed sweetcorn was 3.3 compared to 8.6 in the
control which was continuously under okra, resulting in an increase in
yield within a range of 60-92%. This underscores the potential of rotating
highly susceptible crops with poor hosts in the management of root-knot
nematodes.
A.N. Mweke, J.W. Kimenju, A.A. Seif, E.W. Mutitu and G.K. Mutua, 2008. Potential of Sequential Cropping in the Management of Root-Knot Nematodes in Okra. Asian Journal of Plant Sciences, 7: 399-403.
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