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,results suggest that using of ascorbic acid (at 4000 ppm rate) could be
recommended as instead of chemical nematicide to be a main nematode
management approach, whether using as part of an integrated management
programs or as sole control component.