Host-parasite Relationship of Carrot Cultivars and Meloidogyne chitwoodi Races and M. hapla.

Most of the 15 carrot cultivars tested were moderate to good hosts to Meloidogyne chitwoodi race 1, whereas all except Orlando Gold were nonhosts or poor hosts for M. chitwoodi race 2. All carrot cultivars were good hosts for M. hapla. The plant weights of the carrot cultivars Red Cored Chantenay and Orlando Gold infected with either race of M. chitwoodi were significantly less than uninoculated checks in pots. Under field microplot conditions, however, detrimental effects on quality were rarely observed. M. hapla was pathogenic to both cultivars in the greenhouse and the field. The tolerance level of Orlando Gold to M. hapla was lower than Red Cored Chantenay.