Aqueous Extracts of Organic Mulch Materials Have Nematicide and Repellent Effect on Meloidogyne incognita Infective Juveniles: A Laboratory Study

Summary

While the nematicidal effectiveness of mulching against root-knot nematodes ( Meloidogyne spp.) is calculated within organiccrop protection, underlying mechanisms are not yet fully explored.Laboratory experiments were set up to determine whether mulch-derived substances cause mortality directly, or repel Meloidogynejuveniles from crop rhizosphere. Mortality and area choice testswere conducted with mulch-derived extracts, supported by themeasurements on tannic acid content and the pH values of extractsas supplementary examinations. In our study, leaf litter and strawextracts were generally found lethal to the juveniles, which is inline with the results from area preference tests. However, compostextract had no effect on Meloidogyne incognita juveniles. Tannic acidcontent showed positive correlation with mortality only in the case ofstraw and sycamore leaf litter extracts. Tannic acid and pH weaklycorrelated with repellent effect of the applied extracts generally.Our results have inspired further experiments to explore nematicidalcomponents of leaf litters, contributing to the development of a newapproach in crop protection based on the repellent effect of thesematerials.