ANNE’S MASTERCLASS
How to stop carrot fly from ruining your crop
QCARROT root fly have ruined my carrots. This is so dispiriting after all the effort I’ve put into them. How can I stop this from happening in future? Derek StHolmes, Wiltshire
AAdult carrot flies are so insignificant one hardly notices them, but sadly the third of an inch (9mm) long maggots and their damage are all too common. The first signs of trouble are yellow and then bronze leaves in an otherwise healthy row, caused by the afflicted carrots struggling under the burden of an attack. Pulling a carrot or two soon reveals where larvae have tunnelled into roots causing rusty brown scars. By the time you’ve tried to cut the damage out, there’s little root left to eat, serving young whole carrots raw is impossible and, of course, they won’t store.
Attracted by the distinctive aroma of carrots and to a lesser extent, parsley and parsnips, the low-lying pests home in to lay their eggs in the soil around their targets. These hatch from late May into June and there is another major egglaying session in August and September, the larvae from which pupate inside infected carrots where they’ll stay all winter, ready to hatch in spring. So if your carrot crop is ruined, don’t turn your back on them but take them up and destroy the remaining roots.
There are no chemical controls for carrot fly even if you wanted to use them, so we tend to defeat the pests by stealth. They say that clever sowing times will avoid the fly, but as there are several generations, this is hit and miss. I’ve found that surrounding your carrots with a barrier or, better, covering them with horticultural mesh thoroughly from sowing to harvest are the most effective methods. We have a set of metal hoops and use them to support the covers. Regular readers will have admired Tamsin’s carrot harvest in the 23 September issue. Apparently she also keeps carrot fly off by covering.