Has eelworm invaded the overwintering onions?

You know how it is when it seems something might be amiss with a crop but you hang on in the hope that it was just a silly mistake and it will all blow over as soon as the weather improves. Some hope! We try to celebrate life’s rich tapestry as best we can but when push comes to shove a bit of ruthlessness is called for. These onions, (Autumn Champion, grown from sets), looked fine until a few weeks ago and then, just when they should have taken off, they began to show signs that something was wrong.  We had been careful because we previously lost a crop of leeks to allium leaf miner, and so they were covered with fine insect mesh from winter onwards. However, facts are facts and these onions looked sick.  It’s sometimes difficult for a non expert to diagnose these pests and diseases, but the effect on the leaves was very like leaf miner.  So that gave three possibilities – allium leaf miner, onion fly and eelworm. According to the books it’s a bit early for leaf miner, the mesh should have seen off the onion fly as well and so that left eelworm as the prime suspect. Whatever it was, the remedy was much the same – dig them up and burn them and then don’t grow alliums on the plot for three years.  The RHS rather loftily suggest that the ground should be left fallow, but our allotment doesn’t stretch into the blue remembered hills, and we can’t afford to leave a whole bed empty so we’ll probably try to kill any remaining eggs, cysts or pupae with the flame gun and then observe the rotation carefully.

It’s always sad to lose a crop, but we have the spring planted onions which appear to be OK, and the leeks, garlic and shallots are all alright too, so in a break in the rain and for fear of going stir crazy we went up and did the deed.  As we were pulling them out I examined them carefully to see if any further light could be shed on the problem, and most of the post mortems showed no signs of maggots or pupae, supporting the eelworm hypothesis.  However I did find a couple of plants with 2mm brown pupae that looked very like allium leaf miner – so it was an open verdict. Much as I hate any green material going off the allotment, I’m afraid this lot went straight to the tip. Just for reference or any further ideas I’m including a photo of the pupa and another plant.  Please don’t take this as a sign I know that much about plant pathology, I’m only one page ahead in the textbook!

Author: Dave Pole

I've spent my life doing a lot of things, all of them interesting and many of them great fun. When most people see my CV they probably think I'm making things up because it includes being a rather bad welder and engineering dogsbody, a potter, a groundsman and bus driver. I taught in a prison and in one of those ghastly old mental institutions as an art therapist and I spent ten years as a community artist. I was one of the founding members of Spike Island, which began life as Artspace Bristol. ! wrote a column for Bristol Evening Post (I got sacked three times, in which I take some pride) and I worked in local and network radio and then finally became an Anglican parish priest for 25 years, retiring at 68 when I realised that the institutional church and me were on different paths. What interests me? It would be easier to list what doesn't, but I love cooking and baking with our home grown ingredients. I'm fascinated by botany and wildlife in general, and botanical illustration. We have a camper van that takes us to the wild places, we love walking, especially in the hills, and we take too many photographs. But what really animates me is the question "what does it mean to be human?". I've spent my life exploring it in every possible way and the answer is ..... well, today it's sitting in the van in the rain and looking across Ramsey Sound towards Ramsey Island. But it might as easily be digging potatoes or making pickle, singing or finding an orchid or just sitting. But it sure as hell doesn't mean getting a promotion, beasting your co-workers or being obsequious to power, which ensured that my rise to greatness in the Church of England flatlined 30 years ago after about 2 days. But I'm still here and still searching for that elusive sweet spot, and I don't have to please anyone any more. Over the last 50 or so years we've had a succession of gardens, some more like wildernesses when we were both working full-time, but now we're back in the game with our two allotments in Bath. View all posts by Dave Pole