[Salmo]

Last year every plot had their leeks attacked badly by leek moth caterpillars.

About 3 weeks ago I observed signs of leek moth caterpillars in my leeks. Now I am seeing the cocoons of pupating lavae on the leaves. These are less than 10mm long, covered in a fine web mesh and difficult to spot. Now I have got my eye in I am finding more, both on my leeks and on neighbouring plots. They all appear to be on the upper side of leaves about two thirds of the way up near to the cenrte rib.

It looks like the second generation of moths will appear in great numbers in about 2 weeks time and their caterpillars will decimate all our leeks.

Try as I might I will not find them all and squish them. There is no point in covering with enviromesh as the moths will be under it.

There are no recommended chemicals. Are there, for instance, any soaps or oils that might be worth a try. We need to either kill the cocooned pupae, stop them laying their eggs, or kill the caterpillars between egg hatching and burrowing into the plants.

Any bright ideas out there? We perhaps need to think out of the box.

[pigguns]

Hot damn.  I only planted mine out today. A quick goooogle tells me it's bad after warm dry summers  will be fleecing them over tomorrow then.  I guess the moths are still flying about and laying.

[seaside]

Normally I plant out my well formed leeks in September as one would do for some Spring cabbage type things down here, and harvest right through to April, and that often negates most of the leek moth effect. This year I was so pleased with my leeks, I made the mistake of planting out at the end of May, boldly saying to heck with yet another netted crop, and I got big leek moth problems. A month ago I cut all the affected plants down to ground level. They have now regrown a foot above the soil under mesh.

So thinking outside of the box Salmo, to deal with the  inevitable generation of "sleepers" that are under the enviromesh somewhere, in the next week, I'll be cutting half of the total crop once more to an inch to deal with any cocoons that are hiding in the greenery, then netting that half, and leaving the other half of the crop unprotected, tend and manage them by eye, and see what happens. That way I'm halving the risk and I will get a crop one way or the other. Many leeks survive leek moth attacks and most that are chopped down to the soil level in August still go on to produce good large edible leeks.
I won't be so complacent next year, as I like my leeks.

[Salmo]

I have found an article about leek moth in Germany which suggests removing just the outside leaves rather than. That makes some sence as from what I have seen most of the cocoons are on those leaves. I could then net with the knowledge that most of the cocoons had been removed.

Timing would be important, when all the caterpillars had formed cocoons but before any of them hatch into moths and lay their eggs. From what I can see the first generation layed eggs here in early July and the second generation of moths will be emerging about the end of August. They lay about 100 eggs over a 3 week period.

[Paul Plots]

Luck and timing........

Leek moth is a real pest where I am - it has become so over the last 3 or 4 years.

Planted early enough, so the plants have time to become established, they usually grow through a leek moth attack and often go on to perform well.

Having said that I planted mine out pretty late this year (due to lack of time) so I'm hoping the leek moth misses them as they are still tiddlers so wont survive a good leek moth munching. 

[Ema]

My site had them last year and I'm sure we've got them again. I will have a look at my lot at the weekend. Perhaps some sticky moth catchers too for under the enviro mesh incase you miss any cacoons

[Salmo]

Leek moth may just have a weak point. Some moths need to feed on nectar before they mate and produce eggs. Others mate and produce eggs without feeding. If it is the former then covering with enviromesh with moths underneath will not matter. Does anybody know this? I will try to find out.

[Salmo]

I asked the RHS whether they knew if leek moths need to feed on nectar. They did not know.

I now have a pet leek moth. It was captured as a caterpillar just over 2 weeks ago. After a day or two of munching leek leaves it spun a web and pupated on the side of the jar. Yesterday the moth emerged after 11 days. Pretty little thing with a white spot on its wing. Tiny, just 6mm long.

Presumably the second generation is now hatching out and laying eggs. I have my leeks firmly under a mesh cage.

[devonbarmygardener]

I cover mine with enviromesh from day 1 - ever since I first tried to pull one of my leeks in the early days and got a handful of mush!

[pigguns]

I put mine under fleece but with the recent temps they are looking a bit fried and way too warm.  I'll dig out the shade netting instead for a while then...

[Anton]

Well one thing I read years ago, was to soak the leeks in tobacco juice (kind of a tea made with tobacco leaves) for a few days to repel pests.  I haven't do it for many, many years though. I really can't remember where I read that so I'm not sure it is kosher. The leeks seemed to thrive but that was before the leek moth got into its stride.  I used to use the tobacco juice spray for blackflies and similar.

Antoln

[Yorkie]

Anton, you know the position on this forum about the use of home-made pesticides so please start to abide by it.

[Anton]

Sorry, I didn't realise this was a problem. Mum's the word then.

Anton

[vron]

Hi Salmo, had the same problem (LeekMoth) both with our leeks and our onions.

Then to compound the problem even more, also had Alium leaf miner on all of them.

We just could not believe our bad luck.

To get one is is bad enough, to get both is spiteful.

Still we lifted the lot prepped and froze the leeks.

Prepped all the onions on the allotment, then brought them home to dry.

We were ruthless with the way we prepped them, so that all infected material could be bagged.

We left it all at the allotment till it was green waste day, then put it out for green waste collection.

The onions and shallots are put into blue plastic mushroom trays, and are drying nicely in the mini greenhouses.

They are being shaken daily to see if there are any signs of the Allium leaf miner fly, so far so good.

Just have to keep checking them over.

Hope you can salvage some as we have.

[Salmo]

I asked the RHS whether they knew if leek moths need to feed on nectar. They did not know.

I now have a pet leek moth. It was captured as a caterpillar just over 2 weeks ago. After a day or two of munching leek leaves it spun a web and pupated on the side of the jar. Yesterday the moth emerged after 11 days. Pretty little thing with a white spot on its wing. Tiny, just 6mm long.

Presumably the second generation is now hatching out and laying eggs. I have my leeks firmly under a mesh cage.

Fat lot of good the mesh did. I lifted the mesh yesterday as I could see a high proportion of brown leaf. Almost every plant had a cocoon on the older leaves, some plants had two or three.

What to do? Not that it will help the current crop, but I removed all the older leaves and added them to the Council bin. At least that lot of moths will not be hibernating in the vivinity ready to pounce next year. The leeks look very sad stumps and I know that when they are dug they will be spoiled by tunnels. Looking round other leeks on the site there are plenty of cocoons to be found.

The only ones that appear to have escaped are those that were planted out very late. They are too small to ever make a proper crop and, although they may eventually be dug to flavour something, it is not the way forward as far as I am concerned.

Looks like either covering with mesh or pick them off the shelf in Waitrose.