Abstract

T. P. Mafeo, P. W. Mashela and M. S. Mphosi

Crude extracts of wild cucumber (Cucumis myriocarpus) fruits have been successfully used as post-emergent bio-nematicide in suppression of the southern root-knot nematode (Meloidogyne incognita). Compatibility of this bio-nematicide with plant growth when used as a pre-emergent bio-nematicide was tested on onion (Allium cepa), leek (Allium ampeloprasum) and chive ( Allium schoenoprasum) under greenhouse conditions. In each trial, 10 levels of crude extracts of C. myriocarpus fruits were arranged in a randomised complete block design, with five replicates. At harvest, 18 days after planting, seedling height, radicle length, coleoptile length and coleoptile diameter each were each subjected to the Curve-Fitting Allelochemical Response Data (CARD) model, which demonstrated that at both low and high levels, the bio-nematicide had stimulatory and inhibitory effects on growth of test plants, respectively. The total sum of transformations ( k), expresses the sensitivity of the test plant to the bio-nematicide, k being inversely proportional to the degree of sensitivity. Overall, onion was the most sensitive to the bio-nematicide, followed by chive and leek. In conclusion, since the material had 100% inhibition of plant growth where it suppresses nematodes, the material is not suitable for use as a pre-emergent bio-nematicide.