Allium leaf miner

[ameno]

Well, I've just checked my onions and it seems I have allium leaf miner for the first time ever. The leaves have the tell-tale mottled streaks, and a few of the leaves are twisted (though not many), and inside one of the affected leaves I found a fair bit of insect poo and one single larva.
Looks like I'll have to cover my onions with mesh from next year onwards. Apparently you only need to cover them in the spring, as that's when the adults are laying their eggs, so I shouldn't need to buy any new mesh, as I can have it off the onions before I need it for the carrots.

The infestation does look relatively minor, so hopefully it won't ruin the crop.
Also, I say "for the first time ever", but looking back I feel like I've actually seen these symptoms before but just never thought anything of it (and never checked inside the leaves for maggots). So maybe I have had it in the past but since it never caused the crop to fail I never noticed.

[Mr Bones]

Sorry to hear you have the ALM Ameno. When you cut a bulb up in the kitchen check for fine tracks (about 1mm wide) working down from top to bottom - sometimes the track stops and you'll find the pale maggot or maybe an easier to spot chrysalis.
Ali Miner breeds in autumn too so any alliums will need to be covered then. The flying/egg laying times aren't always as well defined as some reports specify - May 1st (give or take) is spring flight time for us but the autumn time I've yet to pinpoint.

[ameno]

An update on this:
After the leaf miner attack my onions got some sort of leaf fungus, probably downy mildew. I left them for as long as possible to grow as much as they could, then a couple weeks ago I cut the leaves off and binned them, as they were mostly dead anyway and I didn't want to risk infection spreading to the bulbs.
Yesterday I collected my onions in, and today I weighed them, then spread them out in my conservatory to dry a little more before I put them into storage.

So far at least, I have no bad bulbs. All seem firm and good. However My total crop was just under 15kg, compared to 29kg from the same number of sets last year. I fairly dramatic drop.
Most of the bulbs are a lot smaller than normal, thanks to the leaves being demolished by a combination of leaf miner and mildew. Most are at least a half-decent size (the size of the smallish cheap onions you buy in the supermarket), and a few of them are actually quite large (although in previous years most of them have been quite large, and some very large), but some of them are quite small, including a couple only about pickling onion size.

Next year I shall definitely cover with insect mesh until mid or late May. Hopefully keep the leaf miner off will also reduce the chance of getting mildew again, too (I suspect the fungus got in more easily thanks to the damaged leaves).

[Dorothyrouse]

This is exactly how mine were this year, I pulled them out a few weeks ago and am using them, certainly not enough to store, but mine were covered with Environmesh until maybe June. But at least didn’t loose the whole crop

[SimpleSimon]

We have ALM pretty bad. The onions usually don’t get too badly damaged but leeks get decimated. It’s even worse in September so the nets are going back on soon. I’ve managed to control
it this year but not totally avoid it.

It’s strange because a plot not even 50m from
me grows perfect leeks with no nets. So either they don’t travel far or they have some super ALM proof seeds

[Marcusp]

Well, I've just checked my onions and it seems I have allium leaf miner for the first time ever. The leaves have the tell-tale mottled streaks, and a few of the leaves are twisted (though not many), and inside one of the affected leaves I found a fair bit of insect poo and one single larva.
Looks like I'll have to cover my onions with mesh from next year onwards. Apparently you only need to cover them in the spring, as that's when the adults are laying their eggs, so I shouldn't need to buy any new mesh, as I can have it off the onions before I need it for the carrots.

The infestation does look relatively minor, so hopefully it won't ruin the crop.
Also, I say "for the first time ever", but looking back I feel like I've actually seen these symptoms before but just never thought anything of it (and never checked inside the leaves for maggots). So maybe I have had it in the past but since it never caused the crop to fail I never noticed.

Dont forget when planting next year to put them in a different bed. You can guarentee the bed you had them in will have crysalists that will hatch out again in Spring starting the whole cycle again.
we cover our with extra fine micromesh as soon as we plant the sets end of March/April and dont take it off until end of May.
Hopefully you onions should be grown and harvested before September when the second cycle hatches if not cover them again

[SimpleSimon]

The second wave has just decimated my leeks again. I had neglected to the put the nets back on. Must have been laid about a week ago which seems early.