Last year we lost many leeks in our garden due to the leek moth. I didn't know about the problem and none of my gardening books had details - indeed there is not much info as this is a fairly new problem.
Well the moth is back this year - a neighbouring allotment plot holder, Chris Tracey, has just lost all her leeks - she has kindly let me post these photos so others might be able to identify the problem. I also hear that the SCA farm at Brookthorpe also has the problem.
Apparently even the UK Moths website says this is not a pest in the UK as its status is “local or scarce” but they also say it is a pest in Europe. Also that the known lifecycle starts in October and lasts through the winter – we now know that it starts earlier than this. Another site says it was first found in the West Midlands in 2003.
The leek moth used to be confined to the south coast but it is obviously spreading quickly. What a shame - leeks where one of those veg that I have grown reliably for many years with no problems at all. More worrying is that I read that it can also spread to other alliums like garlic and chives. I would welcome
What happens is that said moth lays its eggs on the leek plants, the caterpillars hatch and tunnel their way through each leek with the aim of pupating within the leek or just outside in the roots of the plant. Then the cycle begins all over again.
I have found a picture of the moth here but we are unlikely to see the culprit as of course it will be nocturnal.
On the Saunders Allotment website, it says that “realistically, if you live in an area where leek moth is prevalent the only way forward is to provide some form of physical barrier to prevent the female moth reaching the crop”. Once the maggots turn into moths, in the autumn, they overwinter, and then next year, there they are again! So the only thing for it is fleece apparently or even better Enviromesh. No pesticide exists, but apparently traps are now available - see here. I wonder if chickens might help to get rid of the overwintering critters?