Carrot Root Fly

The carrot fly, Psila rosae, can cause serious damage to carrots, parsnips, parsley and celery as the larvae feed on the roots.

The carrot fly is a small fly with a reddish -brown head, pale legs about 8mm long.

It lays eggs in the soil surface near the host plant. Depending on temperature these hatch in about 7 days and the larvae burrow into the soil feeding on initially on rootlets and then on the root itself.

Later they burrow into the roots forming mines.

There are usually 2 generations of root fly in the year. The first generation emerges in late April/early May with the 2nd generation occurring towards in late July.

practice sound rotation

avoid growing late and early crops close together

keep ditches and headlands well trimmed as flies spend much of their time in shelter around the edges of the field.

dispose of badly infested crops in the autumn by removing from the field - do not simply plough in.

For control of 1st generation flies the use of tefluthrin (Force) seed treatment or using carbofuran (eg Yaltox,Rampart), or carbosulfan (eg Marshal) to give initial control. These products do run out of steam after number of weeks so a spray by also be necessary.

Organophosphate sprays for late 1st and 2nd generation were standard practice for many years but a number of these are no longer available and supermarkets insist on OP free carrots anyway.

Control is now achieved by the use of lambdacyhalothrin (Hallmark, Hero) used just prior to fly emergence and continued while necessary, or until the permitted number of applications have been made.

Sticky yellow traps are used by the growers to let them know when the flies have emerged and how high the numbers are during the risk period.