How to Control Onion White Rot

, written by gb flag

Onion (allium) white rot on garlic

White rot is the number-one threat to onion family crops worldwide. It’s so severe that, in some areas, it has destroyed the allium growing industry. Alarming? Certainly. Treatable? No – not currently, anyway.

However, there are steps you can take to prevent it from entering your garden, and to limit the damage and spread of the disease if it’s already present.

Onion White Rot Symptoms

Onion white rot can affect all alliums, so onions, garlic, leeks and shallots, as well as ornamental alliums, are at risk. I’ve found garlic to be the most susceptible, closely followed by onions. My shallots haven’t yet been affected, and I’ve only ever had one leek show signs of the disease, but I may have just been lucky – if any aspect of having a white rot-infested garden can be considered to be lucky!

One of the worst things about onion white rot is that appears symptomless until it’s too late to do anything about it. The first sign that anything is wrong is usually yellowing foliage, often just before harvest time when you’d expect the leaves to start dying back anyway. This means it’s possible to overlook the disease entirely.


When you dig up an infected plant it will pull free from the soil easily; no tenacious tugging required! Depending on how far advanced the disease is, you may see a mat of fluffy white mould on the basal plate (where the roots sprout from), which will probably have tiny black growths like poppy seeds strewn across it. In severe cases, the bulb will have turned black and be totally rotten.

The little poppy seed growths on the base of infected allium bulbs are called ‘sclerotia’ and these are the means by which the disease spreads. They will drop off and hang around in the soil until another allium crop is planted in that spot, at which point chemicals in the plant roots trigger the sclerotia to germinate and colonise the bulb with white mould.

Close-up of the black sclerotia that are distinctive of onion white rot

Onion White Rot Control

Unfortunately there is currently not a single white rot-resistant variety of allium available, so when buying in young plants make sure they’re from certified disease-free stock. Additionally, inspect the basal plate carefully and discard any that show signs of mould. Or start your plants from seed instead. If your plants do contract white rot, dig up the crop as soon as you’re aware of it, and dispose of every scrap of plant tissue by burning or in your household waste. Do not compost it.

If the infection is not too severe, you may be able to use part of the infected crop. It won’t store dry, so you’ll need to use it fresh or freeze it.

Garlic bulbs that are only lightly infected with onion white rot can be used fresh or frozen

It’s vital to avoid spreading the disease around the garden, so make sure you wash any soil from infected parts of the garden or allotment off your boots and tools before working on other garden beds.

Crop rotation can help limit the prevalence of the disease, but unfortunately the sclerotia can lurk in the soil for many years – far longer than most gardeners can afford to wait between allium crops. You’ll need to avoid growing alliums in the infected soil for at least eight and possibly as many as 20 years. Growing in containers of bought compost may turn out to be a more practical solution.

Garlic Extract Cure for Onion White Rot?

There is a glimmer of faint hope, and that’s adding garlic extract to the soil. The idea is that this causes the sclerotia to sense allicin, the chemical that gives onion family plants their scent. This tricks the sclerotia into germinating and, finding no host plant to infect, they will starve and die. This may help reduce, if not completely eliminate, the disease.

Onion white rot on garlic

To make garlic extract, take a bulb of clean, disease-free garlic and discard the papery wrappers and the basal plate. Crush the whole bulb into 10 litres (two gallons) of water. Water it onto areas of your garden that you’re not currently using for growing allium family crops. Don’t be shy – use a lot!

The whole 10 litres (two gallons) should be applied to two square metres (21 square feet). Do this when soil temperatures are between 15 and 18°C (59-64°F) as this is the optimum germination temperature for the sclerotia. An easier option is to rake or water in garlic powder, which you can buy quite cheaply in large containers from equestrian suppliers.

I’m trialling this technique this year – so fingers crossed! Have you ever tried these techniques, or had success with other methods of white rot control? If so, share your experiences with other gardeners – and me – by leaving a comment below.

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Show Comments


"I've never seen nor heard of this disease in Australia - has anyone else? "
Gypsy on Saturday 16 July 2016
"I've heard you need to water onion or garlic extract on regularly, like once a month, to keep triggering any spores of the sclerotia, for a number of years. I'm really pleased you're trialling this, looking forward to hearing how you get on."
Elspeth Campbell on Sunday 17 July 2016
"Gypsy, if you click the link in the first paragraph, this shows a distribution map which suggests that white rot is present in Australia - as well as pretty much everywhere else in the world, unfortunately! Elspeth, if you're able to water on the garlic solution regularly this could help to trigger more sclerotia to germinate, though I can't say what affect this could have on beneficial soil organisms. It's also important to do it within the temperature range shown above, as this is the typical range that the sclerotia will germinate within. "
Ann Marie Hendry on Tuesday 19 July 2016
"Thanks heaps Ann Marie - unfortunately I keep getting an error when trying the link but I'll keep trying in case it's temporary"
Gypsy on Tuesday 19 July 2016
"Hi Gypsy. It seems to be working again now."
Ann Marie Hendry on Tuesday 26 July 2016
"G'day Ann Marie Thanks heaps. An interesting read but thankfully, nowhere near us. I'll go plant more winter leeks now :) Hooroo Gypsy"
Gypsy on Thursday 28 July 2016
"is it possible to apply garlic powder in the fall and plant garlic in that field in the spring. i planted garlic this past spring and had very good results, good size and a healthy crop. this was my first year with garlic and i had not made up my mind to plant garlic until late feb. i planted march 10 4,000 seeds and allows good . i did pull two or three yellow leaf plants and garbaged them. not knowing anything about white rot . I'm not sure now if that was what i pulled or not. i would sooner be safe than sorry so thats why I'm considering the garlic powder application . could you advise please."
gord hansen on Tuesday 6 September 2016
"Hi, I used this method with great results! I watered 1 crushed garlic per square metre, with lots of water. I then dug the patch over a couple of days later and repeated the process. This was in late May when the ground had warmed up a bit. I then planted squash on the patch and onion sets the following spring. It is important to not put onions in for at least 6 months. The results were remarkable. . As I had done this in a new part of the allotment I then decided that it probably was not thegarlic but simply that this part was clean. I therefore did not bother treating the adjacent patch that I was going to grow onions in next year...there was almost complete crop failure! Needless to say I have treated the next patch last spring ready for next year. I am also going to try just digging in garlic powder whenever I am going to dig in the warm months in the hope that it may just keep knocking the sclerotica back... cheers Norma"
Norma on Friday 9 September 2016
"Hi Gord. You need to apply the garlic powder within the temperature ranges shown in the article above, so unless you live in a very warm climate it's unlikely to be effective in the fall. If you haven't seen any white rot and you're growing from seed then adding garlic extract is not necessary - the disease can only be introduced on infected plant tissue from allium family plants, or in infected soil. Norma, it's great to hear you've had success with this method! Growing on fresh soil this year has worked well for me, so just to be safe, I'm going to dig a new bed for alliums next year and will continue applying garlic extract for another year on other parts of the garden to try to reduce the disease to a minimum. "
Ann Marie Hendry on Tuesday 13 September 2016
"Hi I use garlic powder on the ground with the crop before my onions, sweet corn is the norm. I dress the area in mid June then again in mid July Then last of all mid August. in 2014 I lost 95% of my crop of onions to white rot last year 2015 I lost 20% but that was with only one dressing this year 2016 with 3 dressings I lost 1 onion out of the 500 i grew Yes Garlic Powder Does Work"
John Rendell on Sunday 9 October 2016
"Thanks for the back-up advice John, nice to know. Never seen nor heard of it where we live but all bugs/viruses seem to travel these days, so no doubt it will happen at some time. The majority of us grow our alliums from seed, so I'm hoping that gives us some protection but you never know. Using garlic powder does sound less work than the other method but of course, you'd try all of them if you had a problem! Cheers Gypsy"
Gypsy on Sunday 9 October 2016
"Hi John, Great to hear your post. Do you dig your garlic powder in or just use use it as a top dressing? Presumably your corn is already growing when you apply your last 2 dressings.... also do you water it in? cheers Norma"
Norma on Sunday 9 October 2016
"Hi Again the garlic powder was sprinkled around then hoed in , It was washed into the ground by rain or watering. the garlic had no effect on the sweet corn"
John Rendell on Sunday 9 October 2016
"Thanks for that. I forgot to ask if you know what quantity per sq. yard you used. I have only used fresh garlic.... Norma"
Norma on Sunday 9 October 2016
"Hi about 1 oz per sq yard apx"
John Rendell on Monday 10 October 2016
"Hi John, it's very encouraging to hear that you've found garlic powder to be effective. 1 infected bulb out of 500 is a definite win! Well done."
Ann Marie Hendry on Tuesday 11 October 2016
"White rot of Allium species (caused by Sclerotium cepivorum) has been confirmed in garlic from a Perth backyard and a property in the Swan Valley."
Mik on Saturday 18 February 2017
"G'day Mik Ouch, that's closer to home. I'd never heard of this problem prior to this article but I think it's time I took preventative measures rather than wait for it to hit here and then try to cure it Many thanks for that update Cheers "
Gypsy on Sunday 19 February 2017
"No probs Gypsy"
Mik on Sunday 19 February 2017
"i have had a white rot problem on my allotment for many years and have redwith iterest of all the comments, and i will try the remedys that have been posted. thanks to all who have contributed."
les on Sunday 26 March 2017
"Hello! How long a time do you have to leave after using garlic watering before you can plant out onions/shallots? I got a bit of white rot last year here in SW France. Thanks in advance for your help."
Alan Rippington on Thursday 13 April 2017
"At least 6 months, preferably treat the ground and then grow a crop of something else and plant the onions the following spring. So lots of forward planning needed!"
Norma on Friday 14 April 2017
"Thanks Norma..Well...I guess I'll have to keep fingers crossed for this year. However, I've grown some Golden Bear onions from seed that are supposed to be resistant to white rot. I guess I'm going to find out if this true! (Going to plant out tomorrow)"
Alan FR on Friday 14 April 2017
"Keep us posted on the Golden Bean onions Alan - I'm sure we'll all be very interested to know how you get on!"
Ann Marie Hendry on Friday 21 April 2017
"I've had white rot in the soil for several years, sufficient to ruin 65% of the crop in cool years. The rot favours cooler termperatures, but for the last two years I have dosed at 1oz per sq.yd in the autumn with the temp at 15 degrees Celsius, then rotavated it in just prior to a heavy fall of rain. The exercise is then repeated in the spring using the same parameters. Last summer I did not lose one onion and it wasn't a particularly good one (Sark), so the signs are very positive. I have used the Golden Bear variety for several years and though it fares better than shallots and red onions, is still susceptible in poor summers. It appears to be no longer available in Europe through my suppliers, so maybe that tells us something. In a long hot summer the white rot shouldn't be a problem as it seems anything above 20 degrees C. is outside of its operating range."
Peter Cunneen on Thursday 4 May 2017
"the garlic powder can you buy it from anywhere or do you get it from garden shop .thank you .how much do you use .thank you"
haroon on Saturday 20 May 2017
"i have white rot on my allotment in west yorkshire is it worth trying the garlic powder."
haroon on Saturday 20 May 2017
"Haroon, certainly worth using, but too late for northern hemisphere onions this year. Get the powder from an equine supplier - they use it for treating horses for worms or some such - I order mine through Amazon. Use on the soil now if the temperature is no more than 15 degrees and then again in the autumn, then try onions again in the spring of 2018."
Peter Cunneen on Saturday 20 May 2017
"Hi Haroon, garlic powder can be bought from equestrian suppliers (local stores or online). The last three paragraphs in the article above shows application rates and recommended temperatures for applying it. "
Ann Marie Hendry on Tuesday 23 May 2017
"its warm now here in yorkshire uk .then when should i apply garlic powder to soil.thank you"
haroon on Tuesday 23 May 2017
"how come this is not public knowledge everyone i have asked have told me you cannot treat white rot.but i am going to try this i will buy a soil therometer as not sure what temperature the soil long do i have to do this .will this be a nearly job.thank you i am new at my allotment."
haroon on Tuesday 23 May 2017
"Some people put garlic cloves in a food proser then dilute and water on the ground THIS IS A COMPLETE WASTE OF TIME as the bits of garlic act as a host for the white rot and then wait for onions. BY USING DRIED POWDER THERE IS NOTHING FOR THE WHITE ROT TO FEED FROM hence it withers and dies. I also dress 3 times june july and august about 1 oz p s y just hoe in with normal hoeing then water well. Hope this helps"
John Rendell on Tuesday 23 May 2017
"You can not treat white rot but with good planning you can help prevent it"
John Rendell on Tuesday 23 May 2017
"Hi Haroon, if the temperature is above 18 degrees now and stays that way then it's likely to be too warm for now - but if a cooler spell is forecast it would be worth trying the garlic powder. As John Rendell said above, there is no cure for white rot but it's possible to prevent it using crop rotation practices and avoiding buying diseased plants, and there is anecdotal evidence (much supported by some of the comments above I'm pleased to see!) that using garlic powder may help reduce problems."
Ann Marie Hendry on Tuesday 23 May 2017
"thank you ann and john ,peter i will give it ago."
haroon on Tuesday 23 May 2017
"Crushed garlic does work (see my earlier post) as long as it is a paste..."
Norma on Tuesday 23 May 2017
"Haroon - very sorry, I just realised that I didn't explain about application rates for garlic powder, only garlic solution! Unfortunately I haven't been able to find consistent guidelines for how much garlic powder to apply, however what I've done is sprinkle a very thin layer onto the soil and raked it in well. I hope that helps!"
Ann Marie Hendry on Tuesday 30 May 2017
"Ann Marie and Haroon, I use an ounce or more per square yard, when it's not windy and just before a heavy fall of rain. I then rotavate it in lightly, having already rotavated the bed previously. As mentioned previously, I do this both in the autumn and spring when temperatures are around 15 degrees, so the onion bed has double treatment - it worked a treat last year and I have fingers crossed for this year. Having suffered huge losses over the last ten years this has revolutionised my gardening and reversed a decision to no longer grown onions. "
Peter Cunneen on Tuesday 30 May 2017
"Thanks for the advice Peter. Glad to hear you've had luck with this!"
Ann Marie Hendry on Tuesday 30 May 2017
"Thank you peter and ann marie for your advice"
haroon on Tuesday 30 May 2017
"i just wanted to ask but sounds silly when i have used the garlic powder autumn and spring when do i plant garlic and onions thank you."
haroon on Friday 16 June 2017
"Harpoon, I sow the bed with grazing rye after the autumn garlic treatment and then in March sow onions into deep celled modules which are then transplanted using a bulb planter directly into the soil in May - after having rotavated the grazing rye back in and after the spring treatment with garlic powder. I suppose that sets could be used, but they tend to be planted earlier, which may not necessarily coincide with the 15 degree temperature optimum for the garlic treatment. It doesn't require the green manure, but this just assists soil quality. It is quite a lot of work, but if this is successful this year for me, will be a long-term solution."
Peter Cunneen on Friday 16 June 2017
"Hi I find it best to plan 1 year ahead and treat the ground whilst a previous crop is growing. it is ok to sprinkle around bresicas while they are still young and also in the sweet corn bed.By treating in the late spring and early summer it would be ok to plant over winter setts or garlic in late October then carry on with setts or seed in the spring Over a complete cycle of 4 years you could be rid of white rot but I will still carry on just incase "
John Rendell on Friday 16 June 2017
"thank you john and peter"
haroon on Saturday 17 June 2017
"sorry again i keep asking questions do i add garlic powder where i am going to grow garlic and onion or do i add it to the whole plot.i was telling my neighbour about adding garlic powder etc...she told me her father did the same .years ago .and he grew good onions and garlic."
haroon on Wednesday 28 June 2017
"Haroon, I use independent beds, so I treat the whole bed, but if you aim just to treat an area of your plot you will almost certainly cross-infect and lose any advantage gained. My recommendation is that you treat your whole plot in the autumn when the conditions are as per the detail provided earlier and then again in April or early May when conditions are right again. Sow onion seeds in deep cells and transplant them after the second treatment and if it is a good result you may be able to return to your normal sowing pattern and varieties the following year. Be very careful when using sets as they can be. Source of the fungus. My crop this year is sound, but it's early days - fingers crossed."
Peter Cunneen on Wednesday 28 June 2017
"thank you peter will do ."
haroon on Wednesday 28 June 2017
"It would be better to treet in the summer rather than the autum as the fungus needs the warmer temp to germinate"
John Rendell on Thursday 29 June 2017
"15 degrees is the optimum, John, which where I am is in mid-spring and mid-autumn. Above 18 degrees and certainly 20, it is not active. By sowing seeds individually in deep cells and planting out in May, the bed has had two treatments. I can only go on my own experience and results and this certainly is working so far for me."
Peter on Thursday 29 June 2017
"It needs a temperature between 10 and 20 degrees which, in Britain could happen almost any time of year! I would suggest between early May and late Sept ( I'm in Cornwall) but avoid very hot weather... It's very interesting hearing of the various methods which are all having good results..."
Norma on Thursday 29 June 2017
"I added garlic powder and calcified seaweed to a bed of sandy soil which had a 2" layer of garden compost raked in last September. Just lifted my crop of french banana shallots today. Size is very good, incidence of white rot at lifting is about 15%,"
Gerry Parker on Tuesday 1 August 2017
"Had a great crop of onions this year. Not totally free of white rot but easily enough onions for the winter and the affected ones can be eaten first!"
Norma on Thursday 28 September 2017
"It's encouraging to hear that people are enjoying some success with garlic powder. Keep us updated! Every garden is different, so it's good to know what works across a range of climates and growing conditions. This year I've had a slightly better crop of white-rot free garlic than in previous years, but about a quarter of my shallots have been lightly affected, which is a first for me. Most were still usable though, and fortunately I had a very good yield of shallots (both in quantity and size) which offset the losses."
Ann Marie Hendry on Saturday 30 September 2017
"Ann Marie, I had a large crop of various varieties which stretched down into a more shaded end of the bed. It was here that I experienced white rot in shallots and red onions, but in all the loss was less than 5% of the entire crop. It wasn't a great summer and the shaded end was both cooler and more damp, which may account for the prevalence of the fungus. Only two or three brown onions from roughly 300 showed any signs of the disease. After harvest, when daytime temperatures were around 15 degrees I rotavated garlic powder into the bed and did the same for next year's onion bed. I'll repeat the exercise in the spring when conditions are similar."
Peter Cunneen on Saturday 30 September 2017
"hi, relating to the use of garlic to treat white rot, re powder use, i have a very large area to cover and have had leeks, shallots garlic practically everywhere over last few years, so am thinking i should put it everywhere. as I've got veg stuff in ground now, in most places, it it will be there till it goes below 15-18 - your recommended temp to rake its in, will it be ok to rake it in everywhere now, between all growing veg i mean? if i wait till autumn, when i have more empty spots, but still quite full, the temp won't be hot enough. My garlic has always suffered white rot, and shallots this year for the first time, never on leeks though. thanks. i have a full size lotement, so I'm guessing ill need at least 1kilo to cover this? or more?"
jonathon on Saturday 16 June 2018
"hi, wanted to ask what i should do with the leeks i want to plant out very soon? as i said earlier, I've never had white rot on leeks, just mainly the garlic, and unfortunately I'm now waiting for the elephant and normal garlic and shallots to come up to plant my leeks and parsnips. I literally don't have anywhere else to put them... its 17 - 21 here in uk at mo, so presuming not to bother with garlic powder til nearer autumn? shall i just plant leeks out soon and cover rake in garlic powder everywhere g=regardless of whats still in in the autumn, nr 15 degrees? and then again in spring,regardless of whats in the ground? thanks"
jonathon on Saturday 16 June 2018
"Update (a bit late) on Golden Bear onion: Only 1 plant had white rot in two rows. The neighbouring shallots had 4 in the adjacent 2 I guess it a sort of success. Have planted out some more this year - but not many as the seed didn't germinate very well."
Alan Rippington on Sunday 17 June 2018
"Hi Jonathan. If temperatures are too high then there's little point in raking in garlic powder now - it will have washed out of the soil by the time the temperatures drop. I'd leave it for now and use it on all your growing areas spring. I'm not sure about the exact size of a full allotment plot (or how much of it you have under cultivation), but aim to sprinkle a thin layer of garlic powder over the surface of your beds. The stuff intended for equine use is usually sold in fairly large containers."
Ann Marie Hendry on Tuesday 19 June 2018
"Hi Alan, it's great to hear that you've had success with the Golden Bear onions. Only 1 affected plant is a fantastic result! I will need to try them out next year. "
Ann Marie Hendry on Tuesday 19 June 2018
"Is 15 degrees the air or soil temp? Thanks"
Tracy Rumins on Tuesday 31 July 2018
"Very good question! I had been assuming air temperature, but of course soil temperature is what matters. I've updated the article to include this, then I'm off to buy a soil thermometer..."
Ann Marie Hendry on Wednesday 1 August 2018
"I have it in my veg patch. last summer I made a strong solution of boiled garlic cloves and watered it in once it had cooled onto the bed that was due to have onions in February. I just found a few infected shallots in one corner and the rest of the garlic and shallot crop seems fine. So this year I will do it again, maybe twice, on the bed that will have alliums next year, and be sure to cover the whole bed. I have a 5 year rotation but that isn't long enough apparently."
wrinkly old hippy on Saturday 8 June 2019
"I am losing most of my onions and garlic in the UK to this dreadful disease.I thought 4 years would have been enough not to grow on this patch,but no.I shall try the garlic powder idea,hoping I get the timing and temperature right.I have been knocked back so many times by this,I need that ray of hope ! Keep reporting back guys,I'll be reading and watching xx"
Carole on Sunday 9 June 2019
"Sounds like you're onto a good thing, Wrinkly Old Hippy! (It sounds wrong calling you that, but I mean it in the nicest possible way...) Fingers crossed for you Carole. My garlic is looking healthy so far, but time will tell! "
Ann Marie Hendry on Tuesday 18 June 2019
"A few readers have asked for an update on my garlic powder/extract experiment, so here goes: The first year after applying the treatment (2017) my garlic was less affected while shallots were quite badly affected. The following year the shallots were hardly affected but most of my garlic was infected. This year I grew Longor shallots, Griselle shallots, and a small number of Lautrec Wight garlic plants. I dug up the Longor shallots a little early as they had started to bolt. Not a single one was infected, so this looked promising. However a couple of weeks later I noticed the Griselle shallots looking yellow. I haven't grown this variety before so I was hoping that it was simply a sign they were nearly ready to harvest...but I was fooling myself. Almost every clump was infected - and I'd planted a lot! Frustrating, to say the least. The garlic looked almost ready so I decided to harvest it all so as not to leave it open to infection for any longer than absolutely necessary. Only one bulb out of about 16 was infected. Typically, it was the largest one! So after three years, the results are patchy. I suspect this will be an ongoing process, chipping away at the problem year-on-year, and searching out varieties that show signs of resistance to the disease. I've rarely experienced white rot on Longor shallots, so it may be that they have some degree of natural resistance. Since Lautrec Wight did well this year I'll grow it again. I'll also try the Golden Bear F1 onions that Alan suggested in the comments above. I'd be interested to hear how others have got on with different varieties. The experiment continues..."
Ann Marie Hendry on Friday 5 July 2019
"My update is that in fact all of the garlic was badly infected but shallots grown in the same bed were mostly OK. I think next year I will try the garlic powder for the shallot bed and will grow elephant garlic in pots. Btw I just bought some salad onions that clearly had the beginnings of white rot in their roots."
Wrinkly old hippy on Friday 5 July 2019
"Bad luck about your garlic. It is a really difficult disease to deal with when it can persist for so long in the soil. Growing in containers is a good temporary plan. Best of luck for next year!"
Ann Marie Hendry on Friday 5 July 2019
"Lost most of my show onions also my onions for home so will try the garlic method but as I live in the N/E of England am I to late to apply the garlic powder?"
Dave on Saturday 10 August 2019
"Afraid so Dave - the soil temperatures will be too high. You could try it as the soil starts to cool down again, but it's probably best applied in the spring when soil temps are between 15 and 18C. Sorry to hear about your show onions - it might be worth growing in purchased compost next year to avoid disappointment."
Ann Marie Hendry on Saturday 10 August 2019
"I am in Portarlington, Victoria and have white rot and lost all my garlic and onions! Unfortunately I read your article after I threw my infected onions in the compost bin. The garlic I have thrown into the waste bin. Will the compost be infected now? Should I avoid using it altogether? Or is it only alums that are affected by this disease? What if I grow other veggies using that compost? So many questions!"
Celia on Sunday 20 October 2019
"White Rot - what a scourge! I've been battling it for years. Be careful with the garlic powder. I think we have been unknowingly INCREASING infection (lost 90% this year!) by using it too close to planting. You need to apply it a year before you plant - overwinter - then apply again in the Spring, planting in the Fall. This year I am trying to steam the soil where I am planting. My reasoning is that the fungus can't travel that far before the garlic grows and is harvested. "
Richard on Monday 21 October 2019
"You can use the compost with the white rot in for other veg families but bear in mind the white rot will stay in that ground for up to 20 years! Do you have any flower beds that never grow veg? Garlic has to be applied at least 6 months before onions are put in. I use pulped fresh garlic in water. 1 bulb to 1 gallon per sq metre. Applied twice in May and dug well in, adding extra water. If using powder make sure the ground is plenty wet enough! I apply in May and plant onions the following feb/march. Personally I would not have a shorter gap between treatment and planting."
Norma Holland on Monday 21 October 2019
"I have white rot so i grew golden bear onions.I was pleasantly surprised the white rot only affected the odd one but will be trying the garlic powder for sure."
tahira on Monday 21 October 2019
"I’ve used powder in 2017 and 18 , 90% white rot free. This year 5% free. Same regime, but lots more rain in Durham UK this year. I’m on sandy soil on a south facing slope "
Gerry parker on Monday 21 October 2019
"Celia, as Norma said above, it's best to avoid using compost that could be infected with white rot on any beds that will be used to grow crops in the allium family if possible. This does present problems with crop rotation however. If you're able to grow your alliums in containers of potting soil that could be an option (although potentially a pricey one). Vegetables from other crop families will not be affected by allium white rot."
Ann Marie Hendry on Tuesday 22 October 2019
"Hey, thanks to everyone for this discussion - really useful! I have just started an allotment garden and my first garlic and onion crop is decimated by white rot! I want to try the garlic powder treatment before trying again, but my question is: Can I grow something else in the bed while doing the garlic powder treatment at the same time or is this treatment harmful to other crops? Thanks!"
Rainbow Sprinkles on Wednesday 3 June 2020
"Sorry to hear you've had such a dispiriting start with your allotment Rainbow Sprinkles! It's fine to grow other crops in beds where you're using the garlic powder. It's not an instant fix unfortunately, so if you were to take beds out of production you could see them lying fallow for several years! "
Ann Marie Hendry on Tuesday 16 June 2020
"My whole allotment plot was cursed with white rot and so i started by using garlic water as an insecticide on my greens beans etc through the season and then as the crops were cleared i spread garlic dust over that area i dusted several times up until autumn, do not be shy with the garlic powder. This year i planted on a part of the plot where i had treated and only lost 25% of my crop. In my book thats a win so i am off to spread some powder ready for next year."
pete ball on Sunday 9 August 2020
"Glad to hear that garlic powder is helping Pete. Fingers crossed for next year!"
Ann Marie Hendry on Tuesday 11 August 2020
"Hi everyone. I just wanted to add an update on how my alliums performed this year. The garlic, unfortunately, was pretty much a write-off. Most bulbs were affected. However, I was pleased to harvest my 'Golden Bear' onions (which were recommended in a comment above - thanks Alan!) and find them completely unaffected. They bulbs were quite small, but with only two mouths to feed this isn't necessarily a bad thing. I also grew 'Ailsa Craig' as a control group, and was astounded to find no trace of the dreaded white rot on those either (and they were huge!). I grew some 'Zebrune' shallots too and, miracle of miracles, they were fine as well! I will grow the same varieties next year to see if my luck holds (but might give garlic a miss for a year or two). The bed did get a good mulch of mushroom compost last year in addition to the garlic powder treatment, so that may have helped. Fingers crossed that things are improving though. I hope others are starting to see some success too. Let me know how you're getting on! "
Ann Marie Hendry on Tuesday 15 September 2020
"I have read with interest all the comments on white rot. I had my first dose of white rot last year on my onions. So I have bought some garlic powder and am champing at the bit to use it on my veg plot. The thing is, when the soil is about 15 - 18 c, during the day and down to about 10c at night, do I have to wait until the soil is a steady temp night and day , or jump to it when the day temp. is right. Hope you get the jist of what I am saying. Many thanks."
paul on Sunday 18 April 2021
"Good question Paul! Personally I don't scamper out in the night to take the soil's temperature (I'm sure my neighbours think I'm odd enough without doing that!), so I use the daytime readings as a guide. "
Ann Marie Hendry on Wednesday 21 April 2021
"I planted garlic sets in a newly created veggie plot at the bottom of the garden. It had no history of AWR. Two of the garlic are at first glance unaffected, the remaining 22 are a write-off. they looked so big and healthy, I had top dressed the whole site with very old rotten horse manure. Suddenly a couple of the plants showed sign of distress, and low and behold...I think I'll give alliums a miss in future and stick to legumes, brassica and spuds. At 79 I haven't enough years left to bother with failures!"
Leen Buurman on Sunday 20 June 2021
"Hi all. I live in Sunderland, in north east England and have been infected by this awful disease for many years. I too am trialling garlic powder and this year have planted Golden Bear onions as well as sets and garlic cloves. Due to crop rotation, I have not yet planted sets on previously treated ground so can't comment yet but I want to make a couple of points. Firstly when treating the soil with garlic powder you are only affecting the top few cm of soil so it is unlikely to reach a full spit. So many applications will need to be made before sufficient coverage can be achieved. Secondly I use a butane flame gun to burn the socket where I've removed an infected bulb. This hopefully kills the sclerotia present at that spot and prevents further contamination."
Peter on Monday 19 July 2021
"Hi Peter. It's fair to say that if you normally dig (or double-dig) your soil each year, then raking the garlic powder into the top few centimetres of soil will be of limited benefit. However if you practice no-dig gardening, and simply add more compost or other organic matter onto the soil surface each year, this could in effect bury the sclerotia and help reduce problems. Interesting idea about the flame gun! Burning is certainly recommended for infected material, so that could well work. Let us know how you get on with that."
Ann Marie Hendry on Tuesday 20 July 2021
"In carrying out further research on white rot, I discovered that there is a theory that growing onions and shallots from seed instead of sets/cloves can reduce problems because of the stage of growth the roots are at when the infection typically occurs. Last year I grew shallots and Ailsa Craig and Golden Bear onions from seed and had no problems, while the garlic (grown from cloves) was a disaster, so that seems to support this. I also grow leeks from seed every year without any sign of the disease. I'm not growing garlic this year, but the foliage on my seed-sown onions and shallots haven't shown signs of white rot so far, so fingers crossed! "
Ann Marie Hendry on Tuesday 20 July 2021
""Sorry to hear about every one's struggles with white rot. I live in Montana, USA. Didn't know the name of this issue until I read your posts. A friend of mine plus a local garlic grower and I had issues with white rot several years ago that infected most of our crops. At least I could eat my cloves. I planted cloves from that infected crop the next year and they were fine. Aha! I've foiled it. But, this year my whole crop was infected even though I had planted them in a new bed. However, I had read about planting garlic bulbils last year. Bulbils are the tiny bulbs formed in the garlic scape flower. It takes 3 years to get a crop from them but they will be free from any of the diseases the previous year's garlics may have had. Of course, at that time I didn't realize the problem is in the soil! Now I know not to plant them in the last 2 years' beds. The small 1 year bulbs from the bulbils have no white rot. Yeah! Will try the garlic powder. i also read that a potato farmer in Washington used a cover crop of rye to control what causes the white rot. It's worth trying that, too. Keep persevering! " Montana Susan on Monday 30 August 2021"
Montana Susan on Monday 30 August 2021
"I lost two years onion and garlic to this dreaded disease.I am in the Midlands,UK.I now plant my garlic in veggie bags in used tomato compost.The onions are another matter.I grew 300 this year, a really good crop.Next year,sadly ,in rotation,I know few of the onions had white rot,so there's nothing I can do to that soil.The year after soil,I'm going to try the garlic powder idea this year,keep on doing it and tilling the soil ,see if that works.I am SO INTERESTED in all of you guys and what you are doing.PETER,I shall also try the burn off idea of yours .Another friend puts a good cup of lime in the place the infected onion grew."
Carole on Friday 19 November 2021
"Hi all, I lost about 80% of my garlic this year due to the white rot and happened upon this page via googling. I have an academic journal subscription through work and thought it might be useful to state what I've found in the literature. Most of this comes from this paper: "Efficacy of Germination Stimulants of Sclerotia of Sclerotiumcepivorumfor Management of White Rot of Garlic", 2007 The paper only tracks sclerotia reduction, not yield, which is an important caveat and may explain why the garlic treatment fails in some cases i.e. fractional reduction in sclerotia does not necessarily = fractional reduction in disease. So these researchers found that 2 different grades of garlic powder along with a garlic simulant, diallyl disulfide (DADS) were all equally effective at reducing sclerotia. There is a threshold dose. 56kg/hectare was much less effective than 112 or 224 kg/hectare, which were similar. For reference 224 kg/hectare works out to 0.2 kg for my 100sqft community garden plot, so it is a large but manageable amount of garlic powder, for me at least. I see various recommendations above for waiting time after treatment before planting garlic. This paper found that sclerotia reduction was complete after 3-6 months post treatment. Sclerotia reduction was more than 90% in all fields tested. Now the bad news, subsequent plantings on these fields showed no improvement in yield. I'm still hunting around for papers on whether yearly application, as some folks above suggest, has been proven effective. "
Brandon on Wednesday 19 July 2023
"Thanks for sharing this Brandon - very interesting! My own garden's results have been varied, with some years showing more white rot and others less. I think the problem is that planting and harvesting various crops, not to mention the action of various soil organisms, means the the tiny sclerotia are very easily moved around both horizontally and vertically in the soil, so it's hard to be sure that any application of garlic powder is getting to exactly where it needs to be, especially since the sclerotia are all but invisible in the soil. Only time will tell whether garlic powder and mulching has any effect. Hopefully persistence will eventually pay off, but I suspect the long-lived nature of this disease makes white rot something to be managed once it appears in a garden, but probably never eradicated completely. I hope someone can prove me wrong! I also hope everyone will continue to contribute their experiences and knowledge here, as this is a very useful thread for all gardeners dealing with this difficult disease. Thanks everyone for all your input!"
Ann Marie Hendry on Thursday 20 July 2023
"Thanks Ann. I think your conclusion is probably right. The best paper on repeat applications of garlic powder etc. I found (sadly there is not a lot) is "Reduction of Stromatinia cepivora inocula and control of white rot disease in onion and garlic crops by repeated soil applications with sclerotial germination stimulants" 2019. They found that for 3 applications of germination stimulant at 2month intervals, relative to a control (no treatment), sclerotia were reduced ~90%, incidence was reduced from 100% to 20%, and yield was tripled, for garlic started 10months after the first garlic powder dose. This is a more promising result than the prior paper I mentioned. One interesting thing in the paper was that they tried allium waste as a germination stimulant and that one resulted in a quadrupled yield despite the same degree of sclerotia reduction. Perhaps the extra nitrogen from the allium waste helped or maybe it was a fluke since this was a small trial with small test plots, 3x3.5m. I can't find anything like the strategy people mention here of yearly application of garlic powder on a continuing basis. You'd probably have to talk to farmers or gardeners to know how well that works. It seems like the tactic has at least limited success based on yours and others' experiences. My community garden plot is ~40% allium at the moment. I have nowhere to rotate my crops to so I'll be giving this a try also and see if it helps, but maybe I'll also scale back the alliums some so I at least have something to eat during the season in case it fails. I think I see the rot problem in the onions I have that are approaching harvest (no problem with the onions last year, my first year trying garlic), my leeks still look great though so hopefully I can keep growing lots of those. "
Brandon on Friday 21 July 2023
"Good luck Brandon!"
Ann Marie Hendry on Saturday 22 July 2023

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