A first approach to pest management strategies using trap crops in organic carrot fields

Cultural control methods in integrated pest management (IPM) refer to practices that modify the agricultural environment in ways that favour crop protection to the detriment of pest performance. Trap cropping is one of these practices and involves luring insect pests away from the main crop to a more attractive host plant growing beside or around the crop. The trap crop can then be destroyed, and the pest killed. The carrot psyllid, Trioza apicalis Förster (Homoptera: Triozidae), is one of the most important carrot pests in Scandinavia, and cultural control of this pest could be achieved through the introduction of more attractive cultivars of carrots in the trap crop at different sowing times than used for the main crop. In a multichoice bioassay and a field experiment, T. apicalis females oviposited the highest numbers of eggs on the most developed carrot plants in the trap crop, while different carrot cultivars did not play any role in females’ choice. In the field experiment, probability of damage was highly correlated with number of eggs counted on the plants, which was highest on the most developed plants. The cultivar Bolero was used as trap crop in subsequent trials in three commercial carrot fields in different regions of Sweden. The trap crop concentrated the egg laying to the field edges and it decreased with increasing distance within the main crop from the first row of carrots, while this pattern could not be observed in control plots. These first results are promising, but further trials to better quantify efficacy and to evaluate the spatial design of the trap crop in field, at different sites and population pressure, are needed before trap cropping can be a reliable strategy for carrot psyllid control. •Trioza apicalis prefers to lay eggs on the most developed carrot plant stages.•Early sown carrot cultivars as trap crop arrested the highest number of eggs.•Presence of trap crops reduced number of eggs with increasing distance.