over-wintered onions

[PJ]

Hi Charles. I remember you saying (a few years ago) that you had a hunch over-wintered onions were a source of onion downy mildew (or aggravating it) so I’ve focussed on spring-planted onions instead, including Santero – but they’ve been a dead loss (3rd year) – v small, best treated as shallots. (Ironically my shallots do better!) I see other people on my allotment over-wintering onions so my plot wouldn’t be protected anyway. On RHS website it advises “Onions sown in late summer for over-wintering can carry the disease from year to year. Onion sets for over-wintering, planted in late September should be less vulnerable to being infected and carrying the disease to infect crops sown or planted the following year”
Have you had any further experience about autumn-planted onion sets and downy mildew?

[charles]

PJ yes fair point that at allotments, there is a lot of onion mildew.
I see the logic of planting sets later than seedlings, as long as your sets are disease free, they should be.
Spring sowings need to be in the ground (module sown) by mid April to get established before dry conditions. Mine were good without watering.

[Author]

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