Synthetic chemicals have been used to control plant pathogenic nematodes in the farmers fields. These chemicals, though valued for their effectiveness, are costly and may constitute health hazards to farm households and the environment. Reducing these situations in the farms through use of natural plant extracts is one of the challenges in Nigeria. Powdery extracts of
Jatropha curcas
,
Parkia biglobosas
,
Newbouldia laevis
,
Ficus exasperata
and
Cassia alata
were evaluated for the control of
M. incognita in yam bean (
Sphenostylis stenocarpa
Hochst ex A. Rich) at the University of Nigeria, Nsukka in Nigeria.
Newbouldia laevis extract significantly (P<0.05) controlled the galling of
Meloidogyne incognita, while the efficacy of other extracts were insignificant (P>0.05).
Newbouldia laevis extract had significant effects on the height of the plant. Significant difference was observed on the plants height.
Newbouldia laevis extract reduced the number of galls from 1.89 to 1.18 and increased the height from 106.1 to 213.3 cm and the number of leaves from 59.2 to 69.2 compared with control (water treatment).
Cassia alata extract had a significant effect on both leaf numbers and stem height of the plant. It increased the number of the leaves from 59.2 to 81.3 and the height from 196.1 to 201.3 cm, and the number of root gall from 1.89 to 2.49.
