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

Filtrates of several fungi (Arthrobotry oligospora, Dactylella brochopage, Nematochomus concurrence, Fusarium exsporium, Trichoderma harzianum and Varticillium chlamydosporium) and bacteria (Bacills cereus, B. thuringiensis, Psendornonas fluorescens and Serratia odorifera) as biocontrol agents were tested for their nematicidal against the root-knot nematode, M. javanica infecting sugarbeet plants, as well as for their effects on yield and quality parameters. These microbial filtrates were applied as soil drench at the three concentrates (50, 75 and 1000%). Results showed that all fungi and bacteria filtrates significantly reduced the numbers of nematode population and reproduction factor comparing to the check treatment. The reduction percentage of nematode counts and reproduction factor was affected by microbial filtrate type and concentration used. Enhanced reduction followed increased concentration in each microbial filtrate. Moreover, root, leaves and sugar yields, as well as quality characters (i.e. T.S.S., sucrose and purity %) were also significantly increased. Among the fungi filtrates, V. chamydosporiusm filtrate at the highest concentration recorded the maximum effect in reducing number of nematode population and reproduction factor. Also, the highest increase percentages of leaves, root, sugar yields and sucrose, T.S.S and purity% were obtained at the highest concentrations of V. chlamydosporium. In case bacteria filtrates, the highest reduction of nematode population and reproduction factor as well as, the greatest root and sugar yields increases were achieved at the highest concentration of B. cereus and S. odorifera, filtrates. Generally, the plants treated with V. chlamydosporium, B. cereus and S. odorifera filtrates had less nematode population and higher productivity of sugarbeet than those plants treated with the other tested microbial agents. In addition, these filtrates had nearly the same effect of the nematicide, Oxamyl on root-knot nematode, M. javanica. Also, these biocontrol agents are ecological sound, economical viable and partial substitutes for costly and pollution causing chemical nematicides and have been a successful instead of these chemical nematicides management strategy when used alone or in combination with other strategies.

Water shortages have increased growers interest to investigate the effects of deficit irrigation (DI) levels, i.e. 25, 50 and 75% of irrigation water requirement (IWR) compared with the full irrigation level (100 % of IWR) on sugarbeet productivity and on final population size (p f) and reproduction factor (RF) of root-knot nematode, Meloidogyne incognita, as well as on water use efficiency (WUE) at the end of growing season, under greenhouse conditions. Results showed that DI at the levels of 25, 50, and 75% of IWR decreased significantly yield characters (root and gross sugar yields) and sugar percent of sugarbeet, and increased WUE compared to full irrigation level (100%) treatment, without significant difference between 75 and 100% DI levels in root yield. The yield characters were greatly reductions at DI levels of 25 and 50% of IWR. Among the irrigation levels treatments, WUE was lowest in the 100% irrigation level and highest in the 25% irrigation level. Also, the results indicated that the p f and RF were significantly lower at irrigation levels of 25, 50, and 75% than 100% level. The 75% irrigation level caused minor reductions in root yield, gross sugar yield and sugar percent, but significantly reduced nematode infection (p f and RF) compared to 100% irrigation level. Thus, deficit irrigation to level of 75% of IWR can be utilized to the management of root-knot nematode, M. incognita infection without significant reduction in sugarbeet yields.