Abstract

Nemarioc-AL and Nemafric-BL phytonematicides contain cucurbitacins A and B active ingredients, respectively. The major drawback of the two products had been their phytotoxicity to various crops, which was resolved using the Curve-fitting Allelochemical Response Data (CARD) computer-based model, which also provided overall sensitivities (Σk) of the plant to the test phytonematicides. Two of the seven biological indices were adapted to provide the non-phytotoxic concentration, technically referred to as the Mean Concentration Stimulation Point (MCSP)-which is product-specific and crop-specific. The objective of this study was to determine MCSP of Nemarioc-AL and Nemafric-BL phytonematicides on Swingle citrumelo seedling rootstock and the related Σk of the rootstock to the phytonematicides. Six-months-old seedlings were subjected on weekly basis to 0, 2, 4, 8, 16, 32 and 64% for each phytonematicide. At 84 days after the treatments, MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides on seedlings were 2.97 and 5.6%, with Σk values of 3 and 2 units, respectively. In conclusion, both phytonematicides had MCSP and Σk values which suggested that the two products would be suitable for use on Swingle citrumelo seedling rootstock as a supplement for managing nematode population densities in citrus production.