Evaluation of sweet orange peel aqueous extract (<i>citrus sinensis</i>) as root –knot nematode suppressant

Abstract

The toxic effect of sweet orange peel (Citrus sinensis) was compared with that of carbofuran, a synthetic nematicide, for the suppression of soil and root population of root-knot nematode Meloidogyne incognita ontomato. Field and laboratory experiments were conducted in year 2002 and repeated in the same period in year 2003 at Ahmadu Bello University, College of Agriculture, Kabba, Kogi State, Nigeria. Sweet orange peel aqueous extract was applied at 0, 25, 50, 75 and 100% concentration, while carbofuran was applied at 0, 2500, 5000, 7,500 and 10,000ppm on the field and 0, 250, 500, 750 and 1000ppm respectively in the laboratory on egg hatch inhibition and juvenile mortality of M. incognita. The experiment lasted for a period of six months on the field and seven days in the laboratory for each year. The results from the experiment showed that citrus peel aqueous extract and carbofuran solution brought about significant reduction in nematode multiplication rate and consequent root damage (root gall index) compared with the control. The higher concentrations (7500 and 10,000ppm) of sweet orange peel aqueous extract were significantly more effective than lower concentrations of2500 and 50,000ppm in suppressing nematode population in the soil and root as the performance is at par with carbofuran at that dosage level. The result indicates with respect to all the tested parameters that sweet orangepeel is toxic to root-knot nematode and can be incorporated into its control system as a potential raw material for manufacturing organic based nematicide.