Effects of Planting Date, Cultivar and Vernalization Using Gibberellic Acid on the Severity of Root-Knot Nematode Damage to Globe Artichoke in Subtropical Sandy Soil

Globe artichoke (Cynara cardunculus var. scolymus L.) is a new alternative crop in Florida. This long-season crop poses a very high risk of root-knot nematode (RKN) damage, the most important nematode problem in vegetable production in Florida. This study aimed to examine the impact of RKN damage on artichoke production in the subtropical climate of Florida. Treatments consisted of four cultivars (‘Green Globe Improved’, ‘Green Queen’, ‘Imperial Star’, and ‘Opal’) planted on three different dates (October 5, October 19, and November 2) in Experiment 1, and three cultivars (‘Green Globe Improved’, ‘Green Queen’, and ‘Imperial Star’) grown with or without vernalization using gibberellic acid (GA₃) in Experiment 2. Both field experiments were conducted on sandy soil in west-central Florida during the 2020–2021 and 2021–2022 growing seasons. We collected RKN population density and gall index (GI) data to assess RKN damage. In Experiment 1, all tested cultivars showed moderate to high RKN infection in the 2021–2022 season, with 43% to 75% of roots galled. There was no effect of planting dates on RKN damage in the 2020–2021 season. However, delaying the planting date from October 5 to November 2 reduced the RKN damage while increasing the RKN population densities in the 2021–2022 season. In Experiment 2, all tested cultivars showed high RKN infestation, with more than 80% of roots galled. Vernalization by GA₃ did not affect the severity of RKN damage. Our results suggest that all tested artichoke cultivars are highly susceptible to RKN in subtropical environments of Florida, raising an alarm on the risk of RKN damage to commercial artichoke production and increasing awareness about the need for RKN management.