A review of research to address carrot fly (Psila rosae) control in the UK¹

Abstract

Carrot fly (Psila rosae) is a serious pest of umbelliferous crops such as carrot, parsnip, celery and parsley. Carrot fly has been studied in the UK for more than 60 years. Whilst some of these studies have been focused on insecticides, others have demonstrated the potential for non‐insecticidal methods of control that might contribute to an integrated pest management strategy. These include rotation and spatial separation of susceptible crops; carrot varieties with partial resistance to carrot fly; and crop management strategies to avoid oviposition or the development of severe damage. This paper outlines some of the approaches that have been taken and indicates how these are, or might be, used in practice.

Using physical barriers to prevent carrot fly (Psila rosae (Fabricius)) damage in domestic production

“…In both measures used to quantify damage by carrot fly, damage levels were greater in carrots harvested from the second sowing than from the first. This is likely to be because damage to this second sowing of carrots occurred not only due to the maggots laid by second‐generation flies that managed to overcome the barrier defences and enter the plots, but also from eggs laid by flies that emerged within the barriers, that is the offspring of those that had entered the plots earlier in the season (Collier & Finch, ). This means that when using barriers, damage from carrot fly is usually greater after the second or third generation, where one occurs (Collier & Finch, ).…”

“…This is likely to be because damage to this second sowing of carrots occurred not only due to the maggots laid by second-generation flies that managed to overcome the barrier defences and enter the plots, but also from eggs laid by flies that emerged within the barriers, that is the offspring of those that had entered the plots earlier in the season (Collier & Finch, 2009). This means that when using barriers, damage from carrot fly is usually greater after the second or third generation, where one occurs (Collier & Finch, 2009). This underlines the importance for gardeners to practice crop rotation when using barriers or covers.…”

“…Carrot fly ( Psila rosae (Fabricius)) is an important pest of apiaceous crops including carrots, parsnips, celery and parsley both in commercial production and for the home gardener (Collier & Finch, ; Fox Wilson, ). Crop damage is caused by the fly larvae which feed on the developing roots (Coppock, ).…”

“…Female carrot flies enter carrot crops from field boundaries and lay eggs around plants either singly or in small clumps of up to seven, approximately 3–6 mm under the soil (Ellis, Freeman, Dowker, Hardman, & Kingswell, ; Petherbridge, Wright, & Davies, ). In the UK, carrot flies have two generations per year with a partial third generation at some warm sites in the south (Collier & Finch, ). After the initial colonization of carrot crops from boundaries, flies from subsequent generations can emerge from within the crop.…”

Review of carrot fly control in Northern Europe – 20091

“…These include insect-proof nets and crop covers; partially resistant varieties; crop rotation; selection of exposed sites; delayed sowing to avoid the first generation of carrot fly; early harvesting to avoid the development of severe damage; early harvesting of the crop at the edges of the field and intercropping. These techniques are summarized in Collier & Finch (2009).…”