Our garlic has Puccinia allii. Big. Sad. Sigh. This a fungal disease that affects plants in the Allium family (onions, chives, leeks, garlic etc). Commonly called ‘garlic rust’ it starts on the foliage of the plants (the leaf) and spreads rapidly by leaves touching and/or by spores being blown from plant to plant by wind – so it can VERY quickly take over a whole crop. Some alliums seem to be more prone to it than others. For example while it’s spreading through our garlic crop devastatingly quickly, the clumping onions in the next row seem to be unaffected by it. So I guess we should be thankful for that.
How does it come to be?
It seems that excess moisture, both in the air and soil, plus over crowding plants are the most common causes of rust. In our own garden I initially noticed a slight discolouration on the garlic’s leaves in only one section of the patch, so I made a point to check on it closely ‘later’. However, it was two days before I got back there and by that time the rust was WELL advanced, but just in that one area. This is the region which I have referred to as the ‘mud pit’, as when the excavator created the terraces, the driver got more subsoil on top than actual top soil – bugger. As a result it’s really heavy, sticky clay in that particular spot, and this is where the garlic rust crept in. Yup, it always comes seems back to the soil.
We also planted our garlic closely – but I’ve always planted garlic closely and have never had trouble with rust before. On top of that, we had a very mild and comparatively dry winter, which is why I feel fairly confident in saying it’s probably the high clay content in our soils that ‘fueled’ it on.
Does it kill your crop?
Apparently it can kill your whole garlic crop if you just let it go and don’t try and slow it down. As far as I can tell there is no reliable way to get rid of it (naturally or chemically), but I’m really happy to be proven wrong if you know of a way? Please prove me wrong. What the rust does do is reduce the vigor of each plant it affects, meaning your garlic bulbs will be drastically smaller compared to healthy plants.
Is there ANYTHING you can do??
One blog I read (I read a lot) mentioned that if you prune the affected leaves from the plants this can slow it down and reduce the rate of it spreading, meaning you’ll still get some kind of yield from the crop. And so I gave them a pretty full-on haircut, which apparently they can cope with (fingers and toes crossed). My hope is that this will help them hang in there for at least another 4-6 weeks before I harvest them.
The ‘bald patch’ in the middle of the garlic bed is now being monitored vigorously for further signs of the dreaded rust, which sadly there are.
The healthier sections of the garlic bed are being closely watched with a hint of paranoia thrown in for good measure. I’m going through the patch daily and removing leaves here and there, hoping that this will help the crop hang in there long enough to get a decent yield. But honestly, I have a sinking feeling in my stomach.
EDIT (Nov 2019). This season we had garlic rust again (bummer) and did further research where I found this very useful factsheet from the Australian Garlic Industry Association. It lists a number of ways to treat rust with fungicides, including with copper oxychloride (250g per 100 L of water) and lime sulphur (1L per 100 L of water). We gave our crop one spray using copper oxychloride (which we also use to prevent leaf curl on our nectarine tree) and have been impressed/relieved with how it’s slowed the spread and impact of the rust on our crop. We’ll still need to harvest it a tad early, but it’s helped significantly. Please read the factsheet for complete instructions before applying it to your own crop.
Disease Prevention
Watering: Don’t water your garlic in the evening/night as this moisture will linger overnight and allow the perfect environment for fungus to creep in – water in the morning so the plants can dry out throughout the day. You can also consider installing drip line irrigation to avoid all overhead watering. Of course if it rains at the ‘wrong time’ (in the evening) there’s not much you can do about that.
Soil: If you have heavy clay soils, you can do things like add sand (works on a smaller scale), compost, ramial woodchips and plant your garlic in mounds. However we did most of these things and still got it, so choose another area of your garden with better soil if you have it or consider container gardening for this one crop. Like I said, currently our clumping onions are doing just fine in the same location, so it seems that garlic is particularly sensitive.
Tools: When dealing with any type of plant disease it’s important to sterilise your tools/materials that came into contact with it, i.e. secateurs and a bucket in this case. Make sure you wash your hands before working in other areas of the garden and change/wash your clothes as well – just to be extra careful.
Crop Rotation: To prevent lots of different soil diseases, rotate your vegetable families each season. In terms of planting garlic in the infected garden bed in the future, I read mixed views on how long you should wait until you do so. My research and experience (with white root rot, another garlic disease) leads me to think around 7 years. Luckily we have other spaces so it’s not a death sentence for alliums in our garden… Hopefully. Our market gardening friend – Suzi, has actually made the choice to stop growing garlic due to disease issues which are so common in heavy clay soils (which she also has). I’m hoping that we don’t have to resort to this and will definitely be giving it another crack next season in a different garden bed and with improved soil and new garlic stock.
Wish us luck!
bugger. we had alot of rust in our garlic two years ago. I pulled it a bit earlier than I otherwise would, and about 10% of it had pretty manky bulbs, which we cleaned up and took straight to the kitchen. I used the remaining stock for planting the next year and had a bumper crop! so don’t lose all hope. Garlic hates wet feet, but the rust isn’t like white root rot, thank the gods.
Thanks for the wise words Christina – great to hear all is not lost. We are STOKED that, so far (touch wood), there’s no sign of white root rot. There would be tears!
Very informative post Hanna. I will watch for this type of rust in the future. The only issue I have with growing garlic is black aphid, which attacked an entire crop a couple of years back. I forgot to water the garlic for a week and the aphids moved in to the not so strong plants. Lost most of them, even after spraying the little blighters with chilli, garlic, and onion spray. This did not even phase them.
Yeah those aphids are tough little buggers. I’ve never had them on my garlic (touch wood), but pretty much everywhere else!
TThanks for this post Hannah. Read it a while back and it allowed me to, sadly, instantly identify rust in my crop aafter a month away. Definitely dealing with a mud pit situation here…Thanks for the advice, a lesson learned for next year!
Great post but a real shame 🙁 Our garlic got rust this year. Some of the plants had quite a bit but I think I caught it just in time. I cut off as many affected leaves as I could and hoped for the best. It didn’t stop it completely but definitely slowed it down and we had a good crop of garlic.
Glad you were able to save your crop Gemma! This year our garlic’s looking good so fay, so fingers crossed 🙂
I had rust on my alliums before I brought the soil into balance. Once there was sufficient potassium and the trace elements were abundant, that disease vanished. However, I do not have such a simple solution for rroot rot diseases. I’m trying to solve that one right now. I’m losing a large percentage of my plants to this problem and it doesn’t seem to have anything to do with soil mineralization.
G’day Steve!
Great to hear from you and even greater to hear your advice on garlic rust. Let us know when you crack the garlic rot solution.
Cheers
This is an attractive solution because it’s preventative, however you don’t make clear that the affected plants recovered or whether it only benefitted the next year’s crop. If the latter, you really can’t say it was the soil amendments or some other variable that helped.
Hadvery bad rust last year, after that rotated in a crop of tobacco because it always likes a huge amoubt of sulfate of potash (potassium!). Were very naughty this year and put some garlic in the same spot to see what would happen, garlic in that area is fine, the only patch with problem is the onr we haven’t grown tobacco in over the last few years 🙂
thanks for sharing! so important to know what to do when the chips are down 🙂
I reduced the incidence in my garlic by ensuring that during the very dry spring I watered my garlic. I figured they were stronger less stressed when the cold wet summer arrived and there was very little rust.
S. Quick action is required when bottom leaves start yellowing on the tips, as this is a super fast disease. Rust is in the necrotroph class of fungus disease meaning it kills tissue before consuming the products of decayed tissue. Fine weather is often the best cure. I have lost whole crops of garlic to this disease in wet weather.
I’ve used the “cut it off” method with pretty good results. I’ve moved this year’s crop one row over and hope that I can catch early again. Straw is about three inches thick over the soil of the new plantings and then I spread a mix of shredded paper and cardboard soaked in vermicompost tea over it all and just leave it over winter (Pacific Northwest). The rust did show up, but late in the season. Highly recommend the low water way to go especially in a high clay situation. Watering only the soil also makes a difference.
Sounds good Sally. Yup – we found soil moisture was key to keeping it under control. However, we ended up still having to get new seed and want grow garlic in that bed for a number of years to make sure there’s no chance of it coming back 🙂
I’m really curious about the cause in my garden…I’m in Australia, I live in Tasmania in the south where we usually have cold, wettish winters. This year however we had a super dry winter, I’m on very sandy soil, I rotate my crop each year, on a three to four year schedule. So far I’ve had great success but this year I got rust! Its the driest bed I’ve ever planted in, under gumtrees which is not ideal. After reading your blog I’m thinking it might be because I planted next to egyptian walking onions, which were very close together…. it’s food for thought for sure! I would bet on a lack of minerals too… thanks for your thoughts!
Your guess is as good as mine Louisa! It sounds like the onions might be the only explanation, or if you bought in new garlic seed (bulbs) that year and it came with them….
Same here in Portugal at the coast, super Sandy soil!!! But intense rain in march and april … next year i am going to intercrop. I Will plant them between my strawbwerries. Yes ought! But Ernst Gotsch himself advised it, and he knows What he’s talking about:)
If Earnst says so, then do it :-). !
I’m from Christchurch nz and we are having the hottest spring/summer and my garlic has rust. It’s a month away from harvest time so wondering should I cut the leaves? Leave or harvest early? Bulbs are small but have formed
I’d harvest a bit early – that’s what we had to do the one time we had it. Good luck!
I have lost most of my garlic crop to rust this year. It hit and within two days was over the entire plants. It didn’t bother my Elephant garlic. Also, I have a variety called China Rose and another called Tibetan which fought it off fairly well. Altogether I had seven varieties. The other four were a complete loss. It did not bother my onions or shallots. I think that I may stick to what fought it off from now on. I live in Northern California on the coast; High humidity.
Thanks for sharing Thom!
Yeah all very interesting I too have been hammered increasingly over the last 5 years prior to that it was not a prob in the lower nth island in NZ
Have tried all sorts of things over the years
I have found that the bigger the clove the bigger the bulb even with rust and that climate is not such an issue compared with minerals available so this year am going for a purpose fert mix for garlic
Sounds good and interesting Nigel. Ley us know how you go!
I am in South Africa, in the hottest province of Limpopo. I am a first-time garlic planter. A portion of my garlic field has been hit by rust. We are eight weeks away from harvest and it scares me that we may lose the whole crop. I am gonna remove the affected leave asap. Is it advisable to put potassium and other trace minerals at this stage or must I just bite my nails for the unknown? The bulbs are still relatively small.
Hi Moses, I can’t give advice on the minerals (sorry). Depends on your soil type/condition. We had some luck saving the crop by harvesting a few weeks earlier – it’s never going to be as good as if it didn’t have rust. Good luck!