Table 4.

Repellent activity of Vetiveria zizanioides (vetiver) oil, vetiver root ethanol extracts, and Tagetes patula (French marigold cv. Durango Mix) root ethanol extracts on Meloidogyne incognita second-stage juveniles. The chemotaxis index (CI) was recorded after 24 hr.

Treatmenta	CIb
FMRE 0.1 g/ml	−0.4 dec
2-mon VRE 0.1 g/ml	−0.6 e
1-yr VRE 0.1 g/ml	−0.3 bcd
4-yr VRE 0.1 g/ml	−0.3 cde
VO 0.1 g/ml	−0.1 abc
Ethanol	0.1 a
Sterile distilled water	0.0 ab

^a2-mon VRE = vetiver root ethanol extracts from greenhouse-grown, 2-mon-old cv. Sierra; 1-yr VRE = vetiver root ethanol extracts from field-grown, 1-yr-old cv. Songkha 3; 4-yr VRE = vetiver root ethanol extracts from greenhouse-grown, 4-yr-old cv. Sierra; VO = commercial vetiver oil.

^bChemotaxis Index (CI): ≥0.2 indicated an attractant; between 0.2 and 0.1, a weak attractant; 0.1 to −0.1, without effect; between −0.1 and −0.2, a weak repellent; and ⩽−0.2, a repellent.

^cValues are means of five replications in each of the two trials, for a total of N = 10. Differences among treatments were determined by analysis of variance (ANOVA) and means were compared using Tukey–Kramer’s adjustment for multiple comparisons (P ⩽ 0.05). Similar lower case letters indicate that the means are not significantly different.