Professor University of Hawaii Honolulu, Hawaii, United States
Abstract Text: Plant-parasitic nematodes could threaten the viability of Hawaii's emerging cacao industry by compromising root health, reducing plant growth, and limiting bean yield. However, the host status and damage potential of widespread plant-parasitic nematodes on locally grown cacao cultivars is undocumented. This study evaluated the susceptibility and damage response of two cacao cultivars, ICS-95 red pod and HSCT4 yellow pod toMeloidogyne incognita, Meloidogyne javanica, and Rotylenchulus reniformis. Seedlings were inoculated with 2,000 nematode eggs, and grown in the greenhouse. After three months, biomass was measured, and nematode eggs were collected and counted. A nematode reproduction factor(Rf= final number of eggs/inoculated number of eggs) was calculated. A factorial ANOVA tested the effects of cultivar, nematode species, and the interaction on plant growth and nematode reproduction. A Tukey's HSD for post-hoc comparisons was conducted when appropriate. Both cultivars supported the reproduction of all nematode species(Rfs >1), confirming susceptibility. M. javanica reproduced the most, Rf= 8.25, but R.reniformis caused the greatest biomass reduction, 24% less than the uninoculated control plants. TheICS-95 red pod showed more biomass loss than the HSCT4 yellow pod, indicating higher vulnerability. Infected plants often maintained biomass similar to controls, suggesting potential tolerance traits. These findings offer key data for cacao growers in Hawaii and tropical regions, aiding in cultivar selection and nematode management for sustainable cacao production.
