Greenhouse experimental studies were conducted to evaluate certain biological control agents and other chemical compounds belonging to different groups to suppress the population density of root-knot nematodes (Meloidogyne incognita) in the sandy soil on tomato plants cv. Super strain B.
The biological control agents were the antagonistic bacterium Pseudomonas flouroscence, antagonistic fungus Trichoderma harazianum and their mixture. Meanwhile, the chemical compounds included cadusafos, fosthiazate, carbofuran and oxamyl, as well as the biopesticide abamectin.
The data revealed that carbofuran and P. flouroscenceproved to be the most effective treatments suppressing the final population of root-knot nematodes (Meloidogyne incognita). Both carbofuran and P. flouroscence showed the same effect as the mean reduction of population density reached 92.7%, followed by the mixture ofT. harazianum and P. flouroscence (88.9 %), then T. harazianum alone which achieved a reduction of 88.1%. Fosthiazate was the least effective treatment on population density giving a reduction of 53.7%.
Cadusafos gave the highest reduction percentage (55.3%) on galls/5g roots, followed by abamectin, oxamyl and fosthiazate which recorded 54, 53.9 and 51.1% reduction, respectively. Meanwhile, T. harazianum recorded the least reduction in galls (11.5%).
Abamectin gave the highest reduction (77.2 %) of root-egg masses/5g roots followed by fosthiazate, oxamyl and the mixture of T. harazianum and P. flouroscence (63.9%, 60.9% and 60.4% reduction), respectively.
All the evaluated treatments proved to be effective in enhancing the plant growth of tomatoes and showed indirect effect on the length and weight of root and shoot systems. Abamectin was the superior treatment in increasing the root system length by 44.2 %. on the other hand, the mixture of T. harazianum and P. flouroscence decreased the root system length by 4.1 %.
P. flouroscence was the most effective treatment achieving an increase of 88.7 % in root system fresh weight, followed by abamectin and cadusafos which gave 87.4% and 81.0% increasing. However, T. harazianum showed the least increase in root system fresh weight (20.9%).
Also, P. flouroscence gave the highest increase percentage of the shoot system length followed by abamectin and carbofuran.
In respect to the shoot system weight, abamectin gave the highest increase over all the tested treatments (94.4%), followed by fosthiazate and P. flouroscence which recorded increase of 90.9% and 89.4%, respectively. Vice versa, T. harazianum recorded the least increase in both shoot system length and weight giving increase of 58.7% and 72.8%, respectively, compared with the untreated check.