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Seventeen varieties of sugarbeet either as monogerm or multigerm were screened for their productivity and susceptibility or resistance against the infection by Meloidogyne javanica. All the tested varieties varied in the degree of nematode development and reproduction. Statistical differences in sugarbeet varieties are found between infected and non infected plants in yields of roots, leaves and sugar except, Barca, Pamela and Toro varieties which were not significantly damaged in all these parameters. All evaluated sugarbeet varieties were also significant decreased in percentages of sucrose, total soluble solids and purity except, Esperanza and Toro varieties which were not significantly decreased in total soluble solids and purity percentages, respectively. Four host categories systems were suggested in this study. Root damage index is an average of gall index, gall size and gall area. The combination of the nematode reproduction and root damage index is termed as susceptibility rate. Host vigor percentage is an average of root yield potential and sucrose and total soluble solids percentages. However, host-parasite index as a new term is suggested which expresses the amount of crop damage in yields (roots, leaves and sugar) and quality characters (sucrose, total soluble solids and purity percentages) by nematode infection. The host-parasite index is more suitable because of the generally high correlation between these parameters and crop damage. Thus the Barca and Gloria varieties were rated as a tolerant and Hilma and Helios as highly susceptible, 8 as moderately susceptible and 5 as low susceptible to M. javanica root-knot nematode infection in this investigation.

The host suitability of the ten sugarbeet varieties of monogerm (i.e., Estaban, Francescan, Sander, Sible and Univers) and multigerm (i.e., Heba, Lilly, Mammut, Mirados and Oscarpoly) to M. incognita infection was conducted under greenhouses condition. Results revealed that all yield characters (root, top and sugar yields) and quality characters, (sucrose, total soluble solids and purity %) of such screened sugarbeet variety were obviously diminished by M. incognita infection to great extort. The degree of susceptibility/ resistance of these sugarbeet varieties evaluated according to modified host parasite index (MHPI) scale which was used as a new and suitable scale (special technique) to assess host (sugarbeet plant) reaction. The MHPI is calculated by dividing a gross average of reduction percentages in all yield and quality characters by the susceptibility rate. It could be ranked as standardization of host suitability technique and reporting of resistance of sugarbeet to root-knot nematodes. On this basis, the screened sugarbeet varieties are categorized into three groups, two varieties are as tolerant host (Heba and Sible), four as low susceptible (Estaban, Lilly, Mirador and Sandor) and four as moderately susceptible (Francescan, Mammut, Oscarpoly and Univers) against root-knot nematode, M. incognita. So, they could be Heba (as multigerm) and Sible (as monogerm) varieties recommended as excellent commercial varieties in Egypt, and could be introduced in integrated pest management (IPM) for controlling root-knot nematodes.

Four amino and organic acids, L-arginine, L-glutamic (as amino acids), ascorbic and salicylic (as organic acids) solution applied as soil drench in three concentration levels to evaluate for nematicidal effects against root-knot nematode, Meloidogyne javanica infecting sugarbeet. Their effects on sugarbeet yield and its components and quality parameters were determined. All of the tested compounds reduced the number of juvenile larvae in soil, immature stages, mature females in root, final nematode population as well as reproduction factor, comparison to the check treatment. These compounds were mostly variable in their effectiveness in reducing nematode infesting or reproduction factor and enhancing plant yield and quality according to compounds type and concentration level used. Then, the percentage of reduction in nematode parameters or/and the increases in crop parameters increased by increasing the concentration level of each tested compound. The ascorbic acid was more effective in reducing nematode fecundity, final nematode population and reproduction factor followed by salicylic acid, L-arginine acid and L-glutamic acid in a descending order. Also, the ascorbic acid component showed the best results in improving leaves, roots, sugar yields and quality parameters of sugarbeet in comparison with the other tested compounds. In comparing between the effects of both ascorbic acid and nematicide, Oxamyl on nematode development and reproduction factors as well as productivity of sugarbeet, the ascorbic acid recorded reduction in juveniles larvae in soil, final population number and reproduction factor with values of 76.3, 71.6% and 2.1 fold, respectively as well as increases in root yield and sugar yield with values of 65.73 and 126.51%, respectively, however, Oxamyl recorded reduction to 73.6, 77.3% and 1.9 fold in juveniles in soil, final population number and reproduction factor, respectively as well as increases to 68.09 and 124.12% in root and sugar yield, respectively. The problems associated with nematicides application turned the workers view to focus on new strategies or use new safe components or chemicals for nematode management program. On the other hand, it was obvious from the obtain data, the

Effect of Reniform Nematode,Rotylenchulus Reniformisas Biotic Inducer of Resistance Against Root-Knot Nematode,Meloidogyne Incognitain PotatoA greenhouse experiment was conducted to evaluate the preinoculation of reniform nematode,Rotylenchulus reniformisfor inducing resistance againstMeloidogyne incognitain potato plants. Potato plants were inoculated with reniform nematode three days before the same plants received a root knot nematode inoculation. There was a reduction in the population parameters of the root knot nematode compared to plants given only a single inoculation. The studied potato plants which had two inoculations, also had enhanced growth parameters. The activity of the enzymes; peroxidase, polyphenol oxidase, and chitinase increased in the inoculated plants compared to the non-inoculated control.