[alfman]

You've all probably seen it but if you haven't, D. T. B. sells a strain called 'Santero' and they are very resistant to downy mildew. My plot is covered with it and I've grown these for a couple of years now on it with excellent results and very few bulbs infected. The only down side is they are not a 'wow' type onion but if it means you're going to get a crop, give them a try.   

[Annen]

Thanks for that I will try them next year. My maincrop onions have been affected for the last two years.
Is it too late for this year?

[JayG]

Can't see that Santero are resistant to onion white rot as well as downy mildew - they are two separate diseases.

[mumofstig]

I was about to make the same point, have onion white rot on my plot 

[BabbyAnn]

if I recall, Golden Bear F1are supposed to be onion white rot resistant - however, most sites specify the resistance to mildew than to the rot

[mumofstig]

Tolerant to white rot (from the link)  implies they're still effected, so the bulbs are useless for storing 

[moose]

I think I have posted on this before as I have grown these. I had a bed with white rot and gave it two treatments with caliente mustard and then grew both golden bear and santero. A lot of the santero got white rot but only a few of the golden bear. Not being a properly organised trial I can not draw any definite conclusions. I have moved since doing this and have not experimented any further.

[alfman]

Hi Annen,
              I certainly hope not, mine's going in today. Good luck.

[Ivor Backache]

You can eradicate white rot, its taken me 4 years. First year about 33% were affected, last year it was 1 onion.  My onion bed is 20' (width of allotment ) by 5'.
1. Keep the same bed year after year.
2. Plant no closer than 6". The roots fan out and if they touch the next plant, the rot will travel down the row.
3. I use horse manure and compose it separately from the general compost which will contain weeds from the bed.
4. Onion rot appears June/July, and check the onions by tugging them gently. If they come out easily and have the white rot at the base, then dig out a cubic spade of soil and replace with clean compost and mark with a stick.

You may have several sticks in the ground but they will reduce as you persevere. Cleanliness is essential, make your bed so that you manage it without walking on it.

[Kristen]

I've heard that watering the soil with Garlic / Onion "solution" can fool the Onion White Rot spores into germinating then, finding no actual host plants, they die, and in that way (repeated treatments) the Rot can be eliminated.

I think temperature of the soil at the time of application is critical - has to be warm enough for the White Rot spores to want to germinate.

[Ivor Backache]

I've heard that watering the soil with Garlic / Onion "solution" can fool the Onion White Rot spores into germinating then, finding no actual host plants, they die, and in that way (repeated treatments) the Rot can be eliminated.

Last year, I seem to remember a member advocate this and was going to try it out, but I don't think any result was published. I think the plan was to miss out onions (or grow them in pots) and water the bed very often during the months of June/July with the onion solution. I have read a lot about this but cannot find anything that says it does work. If you think about it, if it did work then there would be commercial preparations on sale, and I have not seen any.

[mumofstig]

A few people did try it, see this thread

http://chat.allotment-garden.org/index.php?topic=97423.msg1080816#msg1080816