Almost a month ago I made a post on this topic, and I asked people to let me know what their personal experiences were. As well as making the post, I sent out some emails and I had some previous discussions with people on the subject. In total I got information from 10 garlic growers all over the world, including myself.
One of the first things I noticed was initially I didn’t get any response from anyone in the US growing garlic, and I had to send some emails and pose the question directly to some garlic growers there. It turns out the reason I didn’t get much reaction from them is garlic rust is just not much of an issue in that region. Rust is only present in a few parts of California and Arizona, and otherwise not in North America. The information I have suggests it is also not present in New Zealand.
It is not possible to draw solid conclusions from the information people sent me. Manure was used from a variety of different animals, at different times in the garden cycle, sometimes it was used fresh and sometimes composed or aged first for different amounts of time.
Under these circumstances, all it’s possible to do is try to look at everything everyone sent me in the broadest and hopefully open minded of ways, and give my opinion about what it all meant in a very unscientific way. In this spirit, what I can say is that with a few exceptions most people who lived in an area where rust was a problem and used manure on their garlic experienced serious rust, and those who didn’t use manure the rust was much less serious.
In addition, a garlic grower in the US send me a link to this publication from the Oregon State University that most importantly says too much nitrogen in your garden can stress the plants and make garlic rust worse.
Growing up in the US I have always been told most home gardens don’t need anything added to them except recycled plant material in the form of compost. You should always rotate your crops, but even the most poorly planned rotation schemes will generally keep nutrients balanced in your garden as long as you are also adding some compost.
It is possible, but not likely, that your garden is lacking some nutrient or combination of nutrients. Unless you know this from a soil test or some other way, you should not add any kind of fertilizer or soil conditioner, organic or otherwise, because you risk upsetting the natural balances in your garden and stressing your plants.
Adding fresh manure (or chemical fertilizers) can be a particular problem because the nitrogen it contains is primarily soluble nitrogen. Naturally occurring nitrogen is usually fixed. The main difference is soluble nitrogen is absorbed much more quickly by the plants (and in this way can easily kill them), whereas plants tend to absorb fixed nitrogen only as it’s needed. This quick absorption of the nitrogen can make the plants grow fast giving us the feeling we are feeding them and making them healthy, when in fact we can be damaging them. The same thing is true with phosphorus, because there are fast and slow acting versions of it. The fast acting versions of the phosphorus can give you similar problems as with soluble nitrogen.
This is what is sometimes referred to as feeding your plants instead of feeding your soil. It’s always better to feed your soil by adding things like compost or growing nitrogen fixing plants, then it is to think along the lines of vitamins and feed your plants NPK (nitrogen, phosphorus, potassium) fertilizers.
For farmers the situation is different, because they often have commercial reasons why they don’t rotate their crops, and they have to deal with economic realities requiring cosmetics and yield on a cost basis. Farmers also usually use commercial varieties of crops which often require special applications of fertilizers and pesticides. Farmers also often have animals and need a way to deal with the waste. We grow things differently and under different circumstances in our gardens.
This year I have purchased a Soil Testing Kit, and I hope to use it to get some information about my garden. I am certain soil testing will not be the end of the story. Nutrients in your garden can vary greatly from spot to spot and season to season, and is also very dependent on what fertilizers have been used in the past as well as what plants have been grown. At the same time, I hope testing the soil will give me an idea if there are any serious problems. I’ll be posting about my results.
Søren and I have been discussing this in email, and he has pointed out there are other ways besides chemical tests to determine if there are nutrient imbalances in your garden. Experienced gardeners can tell just by the way certain plants grow.
For example, you can tell by how brown your garlic gets if you have too much nitrogen in your garden!
Bare Bones Gardener posted not too long ago about using hydrangeas to tell if your soil is acidic or not.
I hope some more people do posts about these kinds of plants, because in the long run this is obviously a better solution than a chemical soil test.
Any feedback on soil type, Patrick? I’m more than willing to believe nitrogen has something to do with rust, but I still feel soil type also plays a part. I know a grower in Wales who piles on horse manure every year, but grows wonderful garlic – no rust. His soil is very heavy Hereford clay, though.
Soilman:
It is possible soil has something to do with it too. When I asked about manure I didn’t ask about soil type, so I don’t have a lot of information about this. Here is what I know:
You told me you have sandy soil and had terrible rust last year.
Rebsie says she has sandy soil and different rust problems in different years.
John (Spade Work) also has sandy soil I think, and had bad rust in 2007 but not 2006.
Mike (PlanB) only had bad rust in early 2007, but not early 2006 I think — remember he is in the southern hemisphere. He has sandy, fast draining soil.
My friend here, Kees, was on heavy clay last year and got bad rust. He uses a lot of not well aged manure.
Søren (Toads Garden) is on heavy clay and had mild rust last year for the first time.
Lieven in Belgium has soil rich in humus that’s not particularly fast draining, and had bad rust in 2006 and 2007.
Until now my garden has been on heavy clay. In 2004 and 2005 no rust, and in 2006 and 2007 mild rust. My garden was also only about 60 miles (100km) from Kees’s garden.
This is what I know. Hopefully if I got anything wrong the people I mentioned will speak up. Otherwise, maybe others will have some information for us?
I don’t honestly see any connection with soil type here, but maybe you disagree? I’ve also read through a number of publications on garlic rust by now, and I don’t remember seeing any of them mention a connection with soil type.
We may know more this year, because some of us are on different soil now.
The following question may take the conversation in a completely different direction, but have you considered the mineral content of your soil? I doubt it would have anything to do with garlic rust, but I remember reading how gardens, even with proper rotation, are usually depleted of the necessary minerals which promote nutrient distribution. Meg and I are just getting into what it takes to remineralize, but from what we’ve read so far it seems to establish a nice healthy balance for the soil.
I have not had rust on garlic yet, I have seen it on weeds nearby so it is around but has not affected the garlic. Why? not sure but here’s a few factors:
My neighbour (an ex-market gardener) grows the most brilliant garlic and onions huge crisp bulbs, but I find it much more difficult producing little bullets most of the time. She used to garden where i do now so she could not understand how come i just could not grow them well. She knows the soil, its sandy, and tells me to cover the garlic rows in the ashes from the autumn/winter burnings. She also tells me when to plant the garlic/onions as she follows the moon for these two crops and potatoes. I must say last year i did get a respectable garlic crop and pretty decent onions, still not in my neighbours league but improving. Meanwhile she gives me onions and I give her tomatoes.
Sorry that was a bit long winded, do you add bonfire ash to the soil Patrick?
Kelly: I don’t particularly suspect minerals are an issue in my garden. My soil is very sandy, and what I understand about remineralizing your garden is you add rock dust. I can’t imagine much would be gained by adding rock dust to sand, but I don’t know really. My soil testing kit doesn’t have tests for minerals, and I don’t know another way off hand to tell. Perhaps I will notice some deficiencies in my plants, and track the problem down to minerals.
Have you had your ground tested or do you have some other way to know for sure there’s a mineral deficiency? If you don’t have a mineral deficiency to begin with, I doubt adding minerals will be of much benefit.
The other thing to keep in mind with remineralizing is it takes a long time to start working, perhaps a few years after you add the rock dust. Are you planning to stay where you are that long?
Laura: I don’t have a handy supply of potash. We don’t have a fireplace in our house, and we aren’t allowed to have fires at the garden. If I had an easy source, I probably wouldn’t pour it over my plants unless I had a particular reason to need to, but I wouldn’t hesitate to add it in moderation to my compost, especially if the alternative was to throw it away.
Potash is a source of potassium, and this is usually present in small amounts in compost anyway, and perhaps this is enough. Hopefully when I test the soil I’ll get an idea if I need to add more, and then look into it.
I don’t have any information about the ground around here normally being low in potassium, I don’t ever hear about other gardeners adding potash to their gardens and I don’t have any reason to suspect it’s a problem in my garden.
As far as the garlic rust goes, it’s a very specific disease that only infects garlic and leeks. There are loads of other kinds of rusts that infect other plants, and of course they are all related. I think in California most of the garlic rust is north of you, in the area around Gilroy, just south of the Bay Area. It’s not that you couldn’t get it too of course.
Mostly what I have found concerning the size of garlic bulbs is the garlic is not yet suited to your garden. This usually happens after regrowing the largest cloves from the largest bulbs for 2-5 years in the same place. If your neighbor is growing great garlic, have you tried growing some of her bulbs?
Otherwise there are a number of viruses and other plant diseases that could be causing a problem. If you like, send me an email and I’ll send you some information about these. One of the most serious is called white rot, are your bulbs rotted at all? This is common in California and if you have it in your ground there is very little you can do about it.
Interesting that the US doesn’t generally have a problem with rust. That would explain why I couldn’t find any mention of it in Ron Engeland’s “Growing Great Garlic” book, which is otherwise a very useful and comprehensive book.
I haven’t used any manure at all on my garlic beds this year, so I’ll keep you posted on the rust situation.
I have found manure to be incredibly beneficial for leguminous crops though. Digging it into the soil before planting my peas has more effect on the yield and the luxuriousness of the crop than any other factor. I use very well rotted manure though, which doesn’t look like manure at all … black and crumbly and sweet-smelling! Part of its benefit may simply be that it improves the water retention of my sandy soil, in which case compost would probably work similarly well.
Rebsie: That was sort of the realization I made. I think most gardeners in the US are less likely to add manure or other high nitrogen sources to their gardens, because it seems like it’s not part of the culture there like it is in Europe. At the same time there isn’t much garlic rust there. Most of the publications about growing garlic and garlic diseases come out of the US. This seems to be why I couldn’t find much when I was researching all of this.
I also agree, there’s not much difference between well rotted manure and compost. Well rotted usually means 2+ years old or mixed with a lot of plant material rich in carbon (like straw) then properly composted. When composing it, you should be thinking in terms of about 90% straw or similar material to 10% manure.
I sometimes add small amounts of manure to my compost, which can make it go faster if it’s lacking nitrogen.
Properly composing manure will fix the nitrogen, and aging it for 2+ years will allow most of the soluble nitrogen to dissipate into the air or wash away.
It’s very important where your manure comes from. Factory farm manure is likely to contain a lot of chemicals and pathogens that can give you food poisoning and make you very sick, all of which can survive composting and aging.
It’s worth adding that I have never considered manure any great or unusual benefit in gardening, and I think you can have a perfectly healthy garden without it.
Thanks for info, Patrick.
Garlic rust may not be a problem for gardeners in the USA, but it IS a significant issue for commercial farmers. Particularly in California, where they have a big problem with it.
This makes me wonder whether there’s also a climate factor, ie hot and dry weather?
Rust on garlic and leek is same species, but different strains. I heard of no rust in leeks in Denmark last summer, but a lot of people had moderate rust in their garlic. Nobody had experienced rust in garlic before. But rust in leek is an oldtimer in Denmark, though usually no big problem.
I made a post on indicator plants, from which you can learn a lot about your soil, including nitrogen level. It is based on european weeds, sorry US.
have you heard of the book “weeds and what they tell”?
it’s by by Ehrenfried E. Pfeiffer
an older book but pretty cool. using weeds as an indicator as to where your soil stands.
not a be all end all but a good start.
Soilman: I’m inclined to think as much as anything it’s global warming and the general degradation of the environment. Having said that, it also seems like it’s more of a problem in areas that are normally damp but experiencing a hot and dry period.
Søren: Thanks for clarifying the difference between garlic and leek rust, I didn’t know that before. I’m really fascinated by your post on indicator plants! I don’t think it’s as specific to Europe as you think. I think gardeners all over the world enjoy Canadian thistle and stinging nettle in their gardens. Some of the other weeds too I think are pretty common. I’m really happy Chris just gave us a link to a book that has more information for people in the US.
Chris: Thanks! The next time I place an Amazon order I’m going to get that book.
Thanks for this great series of posts and responses. We’ve got a bad case of garlic rust on our large crop this year. It’s only our second year on this land and second garlic crop, but as far as I remember last year we didn’t have rust. We haven’t used manure on this ground and we have a light sandy soil. We’re in the Willamette Valley, the main agricultural region in Oregon state.
Now that I’m more aware of rust, I realize we had some in our leeks this spring as well. (they were over-wintered from 2007) Anyhow, we think that some nasty weed pressure (grass) combined with a record cold spring may have contributed to our garlic rust problem this year. It is a fungal issue, right? Now we’re trying to figure out how to harvest in a safe way — we’re talking about THOUSANDS of bulbs. Yikes. We’d like to save our seed again, but would that be crazy?
Hi Katie,
Thanks for your comment! Yes, it is a fungal issue. I haven’t heard of it in Oregon before, that’s not good news for you. If you didn’t already see it, I sort of summarized everything in a comment on this post:
http://www.patnsteph.net/weblog/?p=362#comments
I’m kind of late to the party on this topic, but am facing the same issue. We live at the northern end of the Willamette Valley in Oregon, and half of our garlic in the home garden is decimated by rust. Interestingly, its only on the garlic planted in the back garden where we had garlic planted previously – none in the front with a new garden area. I think the fungus must have hidden away on leftover leaves plowed in, and the cold and very wet spring has just created the right conditions. The bulbs are almost a complete loss. FYI, no manure, just organic compost, in sandy soft soil.
Hi Steve,
Not just the two of you, but I’ve now heard from several people in the Willamette Valley as well as the area around Gilroy California who are getting rust on their garlic. It seems to be getting worse in those areas.
Thanks for the comment. I’m sorry about your garlic! You might try spraying your plants with nonfat milk:
http://www.patnsteph.net/weblog/2009/05/milk-and-rust/
my impression so far is that it’s helping quite a bit.
I have been growing garlic for 5 years now on Southern Vancouver Island, BC, Canada. I have never noticed any major display of rust, or any minor one (which I could have missed), except this year – and it is MAJOR! I planted my garlic on two different spots at the same farm. One patch has severe rust and the other spot has nothing. The spot with rust has been planted with garlic three years in a row. Also on this spot, I tilled in okara – the pulp leftover from making tofu and soymilk, as we have a factory in our town. Okara is very high in nitrogen. I didn’t really like the idea of a high nitrogen fertilizer at the time, and tried to mix in some leaves and other such browner material. Still, in the back of my mind, I thought I shouldn’t be doing this. I didn’t mix any okara into the area that didn’t get rust (and also has never been planted with garlic before). The other thing that I usually do every year, but got to busy to do last fall, is to mulch my garlic beds with seaweed. I have some of the best garlic in my area – except this year, I am totally embarrassed! The bulbs feel soft to the touch and there seems to be a higher amount of rot. The bulbs also seem less formed. We have had a slow and very wet spring, but a month of hot dry weather has made the soil become bone dry. I have read somewhere that applying sulfur can possibly help the bulbs firm up, but is sulfur an organic option and is it too late in the season to try and medicate the problem (I am usually pulling them by now)? Also, I have moved farms this year and I am wondering how safe it is to bring garlic that has been affected by rust to my new planting space?
Hi Jennifer,
I’m sorry you’re having rust problems!
Rust doesn’t normally cause soft or rotted bulbs, it sounds like you may have another problem too.
White rot is common when garlic is not properly rotated, and you might look into if this is what you have. If you do have this, it’s very serious, and may persist in your ground effectively indefinitely. In this case you should not reuse your planting stock.
Rust is generally a regional problem, and as readers of this blog have been telling me they have it, I’ve been watching the garlic rust region in North America move from the area around Gilroy California, to the Willamette Valley in Oregon, now to you in BC. If you move outside of this region, it probably won’t be a problem on your plants, but nothing is for sure. Rust can be spread through spores in plant materials, and you can bring it with you in your plant material. At the same time, the spores are spread long distances by the wind, so if you are in an area that gets garlic rust, it’s simply hard to avoid and planting infected plant material may not make a difference.
Rust is not usually fatal to plants, and if infection occurs near harvest time it may not make any significant difference at all. Rust normally just results in slightly underdeveloped bulbs.
Formally, the only treatment option is applying fungicides before infection occurs. Once infected, there is no known way to treat the plants. I have been experimenting with nonfat milk to prevent infection, and while my trials are far from scientific, I would say so far I’m very positive about it and would recommend it to others:
http://www.patnsteph.net/weblog/2009/05/milk-and-rust/
Again, milk only works on plants that have not yet been infected.
I have heard of using Sulfur, and a friend of mine tried it here last year. Again, there was nothing scientific about the test, but his conclusion was that it probably didn’t help much. Be careful using sulfur, because it can change the flavor of the garlic, making it stronger and sharper.
Every year my plants get infected, and I just let them grow as long as they are sill alive and the tops aren’t too brown suggesting the bulbs are opening in the ground. When the plants are dead, they are dead, and I pull them out. I replant my planting stock the following year. So far I have never had to reuse the same ground twice, I have always found fresh ground, and I would suggest others do the same if they can. Otherwise you should wait at least 3 full years (plant on the 4th year) before reusing the same ground.
I too live on Southern Vancouver Island, on the same farm for the past 12 years and have grown garlic every year. Most years in a new patch. We have horses, so lots of well aged manure, plus ash from the fireplace. Two years ago I renewed my planting stock with nice organic stock from Salt Spring Island, because the stock I’d been replanting for the previous 8 or 9 years had degraded. Had a great crop last year but this year I have rust for the first time ever. And it is really bad. It only started in June, so the bulbs look good, thank goodness, but has taken over the entire bed. Today (late July) I’ve just finished stripping and bagging every single leaf and will be leaving the stalks in the ground to dry up a bit more before harvesting. When I finished, my arms were covered in red dust – it was that bad. We’ve had a very cold wet spring, gardeners around here are estimating everything is three weeks later than usual this year, but had no rain at all for the last month – when the rust appeared.
Fingers crossed next year is better.
Hi Jodi,
I’m sorry about your garlic! Thanks for letting us know about it.
Thanks for your site, I was trying to figure out why my garlic suddenly had rust and the nitrogen connection totally makes sense. However, it wasn’t nitrogen in the soil I believe…..my garlic was looking great. We had a terrific electrical storm, close to 1000 strikes in our area and then a hot spell. From everyone’s comments I’m putting together that the excess nitrogen from the lightning pushed out extra growth that was subject to stress from the muggy heat wave. Thanks again for helping
Hi Ben, thanks for sharing your experiences.