Plant-parasitic nematodes (PPN) are a serious problem in vegetable production and can
cause severe damage to several crops. In rural, low-input farming nematode damage is
much higher and yields can be completely destroyed. Some Commercial nematicides have
been withdrawn from the market due to health and environment concerns. These need to
be replaced by alternative nematode control strategies of which soil amendments is one
alternative. Nine non-crop plant species used in various forms in traditional healing, viz.
Cassia abbreviata, Cissus cactiformis, Euphorbia ingens, Ipomoea kituiensis, Maerua
angolensis, Senna petersiana, Synadenium cupulare, Tabernaemontana elegans and Urginea
sanguinea were screened under glasshouse conditions for their effect on the plant-parasitic
nematode (PPN) (Meloidogyne incognita) on tomato. Subsequent assessments in microplots
and in the field supported the glasshouse results in terms of suppression of root-knot
nematode numbers with crudely milled soil amendments of C. cactiformis, M. angolensis
and T. elegans. Tomato growth responses in these trials showed a tendency of phytotoxic
effects after treatment of soil with crude leaf meal of E. ingens and S. cupulare. In the
microplot study, the overall soil-amendment treatment effect was greater than that of three
soil types on the performance of the tomato, although soil type might have had an effect on
nematode suppression. Due to lack of correspondence between tomato leaf nutrient
contents and the nutrient contents of the soil amendments it is suggested that these noncrop
materials had negligible soil fertilization effects.
In vitro bioassay studies confirmed that extracts of varying polarity of both plant products
M. angolensis and T. elegans might be toxic to J2 stages of the root-knot nematode M.
incognita. All extracts tested of M. angolensis caused immobility of J2, whereas only three
extracts of T. elegans affected mobility of J2 adversely. Duration to 50 % effect, as well as
extract concentration to cause immobility of the J2 varied but where movement ceased the
J2 did not recover for up to 98 hours.
This study has demonstrated the potential of locally available botanical materials for use as
amendments in plant-parasitic nematode management and tomato growth and productivity
improvement. This would particularly be true for small-scale application in subsistence agriculture. It is believed that these amendments could be used as control measures in
integrated nematode control strategies. Their potential use could be adopted by small-scale
farming communities, domestic gardeners and commercial farmers in the Mpumalanga,
Limpopo and Kwazulu/Natal Provinces of South Africa where the relevant materials are
available in useful quantities. Over-exploitation of natural resources should be avoided at all
cost, however. / Thesis (PhD (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nwu/oai:dspace.nwu.ac.za:10394/8705 |
| Date | January 2012 |
| Creators | Khosa, Mbokota Candy |
| Publisher | North-West University |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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