Milk and Rust
Garlic rust is very much on my mind at the moment. Last year around this time it appeared on my garlic, and it just appeared on Gintoino’s garlic in Portugal.
Søren had a good suggestion last year, spraying his garlic with diluted milk, and I’ve decided to try it this year. I’m mixing it about 1:5 with water, only because it’s most convenient to buy milk by the liter here and that’s what works well to fill my spray bottle and cover the plants. I understand nonfat milk is the best to use, but this is a special purchase here and hard to find reasonably priced, so I’m using lowfat instead. I’ve been doing this once a week for the last two weeks, and will keep doing it about this often or after it rains, until it seems pointless to continue.
There isn’t a practical way for me to do anything close to a scientific study here, with a control section of my garden, because once I have garlic rust anywhere it will spread quickly.
What I understand is garlic rust occurs at a time of high humidity, but not when the plants are wet. In my own experience, I see it break out in my garden most often when the days are warm, the nights cool and the humidity is high. Because it seems to be so tied to weather conditions, it doesn’t seem like comparing the date I got it last year with the date I get it this year is a good comparison.
Anyway, to help me figure out if the milk is helping, I would appreciate if anyone reading this who has garlic in their garden will tell me if and when they get rust this year.
Rust is primarily a European plant disease, so those of you in North America probably won’t see it.
Rust is not usually a deadly disease for garlic, but it does reduce the harvest and causes the plants to die prematurely. Delaying the appearence is what’s really important, because an infection two weeks earlier or later can mean the difference between a more or less normal harvest or one that has to be made early.
Comments
13 Responses to “Milk and Rust”
Leave a Reply
I use a dilute spray on my squash, cucumbers, and melons to protect them against powdery mildew. In my small, completely non-scientific control group (aka my garden), I have noticed that plants that I spray regularly with dilute milk before any powdery mildew shows up stay mildew-free longer, and when they do get it, the case is much more mild than without the milk.
I don’t have any experience with rust, but the effect may be the same.
Hi Christina,
I think this was the original logic behind trying milk. Someone corrected me the last time I explained this, but what I understand is that dilute milk has been used on curcurbits for a long time now, and no one seems to understand completely why it works but it does seem to help in exactly the way you say. The leading theory seems to be that it somehow boosts the immune system of the plant. Another possibility is it coats the leaves and somehow blocks and/or slows infection.
Garlic rust is also a mildew like disease, a different family from powdery mildew, but not completely different. The hope is that something similar might happen with garlic rust.
Garlic rust is mostly in Europe (I think Mike of planb says it’s also in South Africa, and I’m sure it’s other places as well), but mostly not in the US. Garlic is also not always thought of as a very important crop in Europe, and rarely grown in home gardens. This means not a lot of attention is being paid to garlic rust, and it’s very likely no one has ever tried using milk before.
Perhaps the chances of success are small, but I think if garden bloggers don’t try no one will. I think the hardest part may really be knowing if it truly does something useful.
I’ll be interested to see how you get on with this. We have had rust on our garlic for the last couple of years and any ideas to slow it down would be much appreciated!
It’s interesting that you say garlic rust is mostly in Europe. My garlic was severely infected with rust this year (I’m in California). Is it a different strain of rust in Europe? Can the same strain of rust infect different types of plants? I thought that my garlic might have been infected with rust that may have infected roses that were previously grown in the same area. Garlic that I grew in a different area was not infected and the cloves that I planted came from the same bulbs as the infected plants.
I let the infection go too long before I treated it with Neem oil. The Neem killed the rust and it stopped spreading, but it was too late and the garlic didn’t get very big. Does milk kill the rust once it has started to infect the plants or is it just a preventative? I’ve used milk to treat powdery mildew on squash plants but found that Neem is far more effective. By the way, Neem is approved for organic growers here in the States. It has very low toxicity to beneficial insects, especially if it is applied when they are not active, such as very early in the morning.
Hi Michelle,
Thanks for the comment!
If what you have is killed or even slowed down with neem oil, I doubt it’s the same rust we have here. Not even commercial/chemical sprays are effective against rust after an infection takes place. The only option garlic farmers have here is to begin spraying before a possible infection may take place, and continue until harvest. It’s very similar in this respect to potato or tomato blight.
Commercial preventative sprays are very toxic.
Milk too only has the possibility to prevent or slow infection.
Garlic rust is very specific to garlic. It’s not possible to get it from plants like roses, even leeks get a form of rust that’s unable to infect garlic.
It’s been a year or so since I read this, and I would have to double check to make sure, but what I remember is the only two places in the US with garlic rust are central California in the area around Gilroy, and a few small areas in Oregon. Of course this could have changed a bit in the last few years, but I haven’t heard of widespread outbreaks in the US. None of the garlic growers I’m in contact with in the US have never seen rust before.
Probably what’s more important than what you do to prevent rust are the things you don’t do. In particular garlic rust is associated with excessive nitrogen/fertilizer use, or the use of fresh animal manure. Garlic also likes a lot of organic material in the ground. Keeping your plants healthy in this way can go a long way to reducing rust problems.
Hi
Whilst searching the internet regarding rust on my garlic – I came across your website. My garlic seems to be quite badly affected but, to be honest, has only 2 – 4 growing left to do. Should I take it up now or leave it? What happens to the bulbs if left? Can it spread to onions?
I’d be grateful for any advice as I can’t find answers in any of my books.
I live in south West France by the way.
Bev
Hi Bev,
Sorry to hear about your garlic.
I doubt the rust can spread to your onions, but I’m not completely sure.
I suggest leaving the bulbs in the ground as long as possible, but of course when the plants are dead, they’re dead, and there’s no point in leaving them in the ground any longer.
Your garlic should be normal, except if you have to harvest early it will be smaller.
Rust does not normally infect the bulbs, only the leaves. Having said that rust does spread the longer you leave your garlic in the ground, and you should be careful to destroy the infected parts of the plants and not put them into your compost.
You will reduce your chances of getting rust early again next year if you are careful this year not to spread it too much, and it’s best to use planting stock you are completely sure is rust free if you can get it. Also like I said above, for next year, too much nitrogen fertilizer or fresh animal manure is known to make rust worse.
Thanks so much for your advice Patrick. There is no sign of rust on my onions and I have some right next to the garlic – so I think you’re right. I used chopped up leaves collected from the woods near my house as a mulch. Do you think this might have contributed to the problem? There are so many it seemed like a good idea at the time.
Regards
Bev
Hi Bev,
I don’t think there’s any problem with the leaves. Garlic rust is usually spread by the wind, and if it were to be in the ground the leaves might help prevent it being splashed up by the rain and so could help.
I cover my garlic with straw. Using something to cover it in the winter helps a lot because the temperature can vary a lot in the winter, for example it can freeze at night but the sun can shine brightly during the day and warm the ground. While garlic can tolerate mild to very cold temperatures, it doesn’t like these changes, so covering the ground can help a lot. Of course it also helps with the weeds.
I read a study at an American university a few years ago that said when you cover the ground, the garlic grows 10% bigger.
Other than making sure you don’t give the garlic too much fertilizer or fresh manure, I don’t think there is much you can do about the rust. Like I mention here, I’m experimenting with milk, but I don’t really expect it to help. Mostly you just have to hope the garlic rust comes late in the season.
Hi Patrick
Thanks again. It’s interesting what you say about covering the ground. I do it mainly to conserve water but also to prevent weeds. I seem to spend most of my life either watering or weeding. I don’t mind either but water is so scarce and expensive. I wouldn’t be able to say if covering has increased the size of the bulbs yet but will bare it in mind in the future.
I’ve pulled up a few of the bulbs and they are of reasonable size. I think I’ll follow your advice and leave the rest for a month or so.
Hi Patrick, thank you for the great information. I’m going to have to do some reading on this topic. Gilroy isn’t all that far from here…
Hi Patrick, now you’ve got me wondering if the Neem did stop the rust or if it had just run its course and/or weather conditions didn’t favor it any more. It will be interesting to see if it returns next year and I try the neem before the rust runs rampant. I’m also interested to see the results of your milk treatments.
After a bit more reading, I found that garlic rust is also present in the Salinas valley, even closer to me than Gilroy…
[...] really hard to say if the milk I used made any [...]