Onion White Rot
Moderators: KG Steve, Chantal, Tigger, peter
Is it true that the soil must be left fallow of onions for up to seven years,if Onion White Rot contaminates it. Iwas unfortunate enough to have this vile affliction appear in my veg plot three years ago and have not sown onions since. Would it be wise to try again this year. I have always rotated my crops each year, so obviously this is not the soloution
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oldherbaceous
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Evening John P, i think a lot will depend on, how early and how you disposed of the onions that had the White Rot.
The big problem with White Rot is, that by the time it gets noticed, the small black resting bodies of the fungus have often developed and fallen back into the soil, to infect the soil again for future crops.
So if the infected crop was cleared and burnt, while the fungus was at the white fluffy stage, the infection in the soil will be low.
But if they were left in the soil to rot, the infection will probably still be fairly high.
I think i would just try a few sets this year, on a piece of ground that wasn't affected, but keep a very close eye on them.
Maybe even pulling the odd one up to check, and even be prepared to destroy all the crop if need be.
The big problem with White Rot is, that by the time it gets noticed, the small black resting bodies of the fungus have often developed and fallen back into the soil, to infect the soil again for future crops.
So if the infected crop was cleared and burnt, while the fungus was at the white fluffy stage, the infection in the soil will be low.
But if they were left in the soil to rot, the infection will probably still be fairly high.
I think i would just try a few sets this year, on a piece of ground that wasn't affected, but keep a very close eye on them.
Maybe even pulling the odd one up to check, and even be prepared to destroy all the crop if need be.
Kind Regards, Old Herbaceous.
There's no fool like an old fool.
There's no fool like an old fool.
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oldherbaceous
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Just out of interest John P, you didn't start using the recycled council compost when the problem arose did you?
One more thing, what part of Bedfordshire are you in?
One more thing, what part of Bedfordshire are you in?
Kind Regards, Old Herbaceous.
There's no fool like an old fool.
There's no fool like an old fool.
I agree with OH on this. I have learnt to live with the white rot in my veg. patch. The alternative would be not to grow any onion type plants for many years and hope the soil cleaned itself.
I start onions and shallots in pots of compost and plant out about 1 foot apart when they are well established. I always loose some plants and some years are worse than others. I keep a close eye on them and at the first sign of trouble I dig out the affected plant with some of the surrounding soil and bin it. This wider spacing seems to reduce the chances of the infection spreading down the row. Also I always grow in different area each year.
John
I start onions and shallots in pots of compost and plant out about 1 foot apart when they are well established. I always loose some plants and some years are worse than others. I keep a close eye on them and at the first sign of trouble I dig out the affected plant with some of the surrounding soil and bin it. This wider spacing seems to reduce the chances of the infection spreading down the row. Also I always grow in different area each year.
John
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What we observe is not nature itself, but nature exposed to our method of questioning Werner Heisenberg
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Hi John,
There was an experiment a few years ago which was to scatter and lightly dig in pieces of chopped onion and the idea was to attract the spores to grow but because the onion bits die off before the disease has a chance to proliferate. By attracting these to grow it was an attempt to shorten the replanting period. The only trouble is I cannot remember if it worked or not! Tempis fugit I'm afraid!
JB.
There was an experiment a few years ago which was to scatter and lightly dig in pieces of chopped onion and the idea was to attract the spores to grow but because the onion bits die off before the disease has a chance to proliferate. By attracting these to grow it was an attempt to shorten the replanting period. The only trouble is I cannot remember if it worked or not! Tempis fugit I'm afraid!
JB.
Hello OH, No I didnt use recycled compost. I live in Arlesey and though I dont know many veg gardeners in the area(more flowers) those I do know have not had this problem.Mind you some of them have never heard of it so they are not much help. Anyway I will give you and johns suggestions a try and see what happens PS, read in a garden book yesterday that there is no known dure. only time .
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oldherbaceous
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Evening John P, i had some work done on one of my motobikes at R.J.M's at Arlesey.
Kind Regards, Old Herbaceous.
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peter
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Small world, a former colleague with a "dodgy mota" lived in Arlesy, had to ferry him home a few times. A current colleague plays for Arlsely Ladies FC. 
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It just so happens that I came across this suggestion last week for the organic control of white rot in alliums, and as it is such a common problem on allotments, it will be of interest to others.
This method of organic control of white rot was suggested by an expert on alliums, Professor Fred Crowe, Oregon State University, after ongoing tests.
When white rot has infected allium roots and bulb, it forms thousands of little black seed like, sclerotia, which fall off and remain in the soil, unless the infected bulb, roots and the adjacent soil have been removed and sterilised. When the sclerotia infected ground is dug over, the sclerotia will be distributed throughout the digging depth. These sclerotia will become dormant over the Winter, but in the Spring will germinate as soon as they sense the presence of allium roots close by.
The control method is to trick the dormant sclerotia into thinking that there is an allium growing beside it, by watering on a ground-up garlic bulb solution of 1 part garlic solution to 1000 parts water, say one ground-up garlic bulb to a watering can of water. Apparently, you should be able to taste and smell the garlic in the solution. It should be applied when the ground temperature is between 10c and 20 c with an optimum temperature of 15c.
It should be watered onto the ground that you intend to use for alliums, during the preceding year while the ground is moist and warm.
It is also possible to use garlic powder which you can find in Asian food shops and health food stores. This should be applied at a rate of 250 lb to the acre. Roughly 125 Kg per 4000 sq m, or roughly 30 gm per sq m if my arithmetic is correct. This has the advantage of having been sterilised and unable to pass on any allium infections but is not so effective.
The above is my summary of a transcription of a lecture that he gave. The transcription is rather heavy going but is on line here http://www.bcseeds.org/white-rot.php
This method of organic control of white rot was suggested by an expert on alliums, Professor Fred Crowe, Oregon State University, after ongoing tests.
When white rot has infected allium roots and bulb, it forms thousands of little black seed like, sclerotia, which fall off and remain in the soil, unless the infected bulb, roots and the adjacent soil have been removed and sterilised. When the sclerotia infected ground is dug over, the sclerotia will be distributed throughout the digging depth. These sclerotia will become dormant over the Winter, but in the Spring will germinate as soon as they sense the presence of allium roots close by.
The control method is to trick the dormant sclerotia into thinking that there is an allium growing beside it, by watering on a ground-up garlic bulb solution of 1 part garlic solution to 1000 parts water, say one ground-up garlic bulb to a watering can of water. Apparently, you should be able to taste and smell the garlic in the solution. It should be applied when the ground temperature is between 10c and 20 c with an optimum temperature of 15c.
It should be watered onto the ground that you intend to use for alliums, during the preceding year while the ground is moist and warm.
It is also possible to use garlic powder which you can find in Asian food shops and health food stores. This should be applied at a rate of 250 lb to the acre. Roughly 125 Kg per 4000 sq m, or roughly 30 gm per sq m if my arithmetic is correct. This has the advantage of having been sterilised and unable to pass on any allium infections but is not so effective.
The above is my summary of a transcription of a lecture that he gave. The transcription is rather heavy going but is on line here http://www.bcseeds.org/white-rot.php
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oldherbaceous
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Thanks for that Realfood, very interesting indeed.
Kind Regards, Old Herbaceous.
There's no fool like an old fool.
There's no fool like an old fool.
I like the sound of the theory as well. But I think that you need to do the treatment the previous year, while you are still growing non-alliums on the ground that you intend to grow alliums on the following year.
If you applied the treatment now on the ground that you intend to grow alliums on this year, you will just activate all the white rot, which is not what you want.
If you applied the treatment now on the ground that you intend to grow alliums on this year, you will just activate all the white rot, which is not what you want.
Further to my problem with White Rot,and in answer to the helpful suggestions I received. Ihave had mixed luck this season. Planting in a different part of the garden to three years ago,a row of twenty looked good until July,then I noticed nine with the disease,the rest survived,so at 50% or so I have had improvement on my last attempt. I burned the diseased plants. I planted a further twenty sets in two cold frames joined together in a non vegetable part of the garden. I mixed home made compost with the soil prior to planting,much to my delight all remained disease free.A much better result then I could have hoped for. I sprayed the section where I had early spuds in late June with ground Garlic,so I look hopefully to next year and maybe disease free onions