Protecting Crops from Nematode Pests: Using Marigold as an Alternative to Chemical Nematicides

Published by the College of Tropical Agriculture and Human Resources (CTAHR) and issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Andrew G. Hashimoto, Director/Dean, Cooperative Extension Service/CTAHR, University of Hawai‘i at Mänoa, Honolulu, Hawai‘i 96822. An equal opportunity/affirmative action institution providing programs and services to the people of Hawai‘i without regard to race, sex, age, religion, color, national origin, ancestry, disability, marital status, arrest and court record, sexual orientation, or status as a covered veteran. CTAHR publications can be found on the Web site . T primary soil-borne plant-parasitic nematodes impacting cropping systems in Hawai‘i are the rootknot, reniform, cyst, burrowing, and lesion nematodes, all of which contain spear-like mouthparts used to puncture plant roots and obtain nutrients. These nematodes cause significant economic damage to a wide variety of crops. After crops are infected with nematodes, crop yield and quality are reduced, either directly from root deformation caused by nematode feeding or indirectly from predisposition to infection by other pathogens that results from nematode penetration into the roots. The methods most frequently used for managing nematodes in agriculture include rotating crops with plants that are not hosts of plant-parasitic nematodes, using resistant plants if available, and applying chemical nematicides. Additional methods include soil solarization and the use of organic amendments, trap crops, microbial biocontrol agents, and plants that are antagonistic to parasitic nematodes. This publication focuses on the latter alternative and specifically discusses the potential use of marigold plants for managing plant-parasitic nematodes found in Hawai‘i and other regions.