Onion white rot

Hi, I have an allotment that was I struggle to grow onions on without them getting white rot. It’s been suggested to me that it’s worth trying to spray the soil with an onion spray for two years, this will activate and exhaust the host pathogen. Thoughts please. M

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Hi Markie, welcome!

Yeah, I have it on my plot and gave up planting in the ground and use containers for onions & shallots.

According to the RHS there are no chemical treatments and is almost impossible to get rid of (it is carried on tools, shoes, soil). Allegedly, the fungus can remain in the soil up to 15 years (yikes).

Anyone else have any suggestions?

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Hi Markie, welcome to the community! Great question and good advice from @Belovedporcupine. I’ve heard this organic method suggested for dealing with brassica club root but not for onion white rot.

In theory it will be worth a try as you may weaken it enough to grow some successfully but as Belovedporcupine mentions, it will be in the. soil for 15-20 years so unfortunately it’s unlikely to vanish.

It could also be worth trying long rotations of say 5 years - the idea being that the fungus in the soil is so weakened that you may get some to grow OK each time before the rot takes hold fully.

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Thank you both, as you say it’s a problem but not one that’s going to beat me, heavy rotation and fingers crossed


Please keep us informed how you go, fingers crossed for you!

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