ABSTRACT

A study was conducted to determine the susceptibility 0fauSa potato to the root-knot nematode, M incognita and possible control of e disease organism uS1flS plant extracts. In the green house experiment, thiy (30) polags were each filled with 10 kg of steam sterilized sandy loam soil. One seedling of Haisa potato was planted into each polybag and inoculated with 0, 1000, 2000, 3000, 4000 nd 5000 eggs of M ,iita. Tt, fh cnnd nd third exoeriments in the green houe and field, respectivelY the nematicidal effect of Pleurotus tuber-regium, Neen-leaf ash, carbofutan and combination of these three-materials (combined approach') were determined and compared on potato plants inoculated with 5000 nematode eggs in a naturally infested soil. At a nematode population of zero ('0') the highest number of tubers were obtained and no nematode symptoms were observed whereas the least number of tubers were obtained at a nematode population of five thousand (5000) which also had the highest galling symptoms. Combined approach (the combination of P. tither regürnr and Neenileaf ash gave a percentage reduction of 53, 50, 45 and 44, respectively, of nematode in the soil between planting and harvesting time. The polybag without any treatments had about 131 percent increase in nematode population. Polybags with treatments had reduced number of nematodes extracted from their root, tubers and soil. The soil without any of these treatments had the highest number of nematodes extracted from the roots, tubers and soil. All the treatments significantly (P = 0.05) reduced the number of nematodes in tubers, roots, soil and also the number of galls on roots when compared with nematode alone treatment. Combined approach treatment and treatments with neem-leaf ash, carbofliran and Pleurotus tuber-regium respectively improved the number of tubers per plant than the control (nematode alone) even though they did not differ significantly (P 0.05) from each other. Combined approach treatment and neem leaf ash, appeared to give higher fresh tuber weight than carbofuran, and Pleurotus tuber- regium but they did not significantly differ.