Black Aphids On Garlic

A big part of gardening is discovery and learning.  This year, I have learnt a few things about my veggie patch. 

For the first time, my garlic crop is suffering from an infestation of black aphids.  Below is a photo of the most infested plant.  They just love sucking the sap out of the leaves and stem.  And here was me thinking that garlic had no natural pests.  I was so wrong.
I have been keeping an eye on them for the past week, hoping that a beneficial insect predator would come along and cull the infestation.  So this morning when I checked, it had just got worse and no friendly insects in sight.  Instead of losing my entire crop of Australian Purple Garlic, I had to take action.
Sap sucking insects do not like being sprayed with Eco-oil.  It gets clogged in their spiracle and they suffocate.  I rarely uses a spray, but this infestation was not going to get better by itself.  Eco-oil is an organic product made from plant oils and an allowed miticide and insecticide in organic systems.
This stuff is easy to use and I added 5 ml to 1 litre of water in my spray bottle, and sprayed the entire crop of garlic.  It took about 6 litres to spray everything, and I must say that the garlic looked much better this afternoon.  The instruction mention that I should spray again in 3-5 days, so will give them the once over on Thursday to make sure.  
Tomorrow I will share another gardening problem that I have experienced for the first time.  It has to do with broad beans.
Has anyone else had this type of infestation?


  1. says

    Hi Gavin
    Thanks for the tip re-aphids and garlic. I have been spraying mine with a natural aphid spray pyrethrum, it seems to work for a few weeks then their back again; same infestation as you have been having by the photo you posted. I have not experienced this before with my garlic so was quite shocked and miffed, I just hope my garlic bulbs are healthy when I harvest them. They seem very persistent.

  2. says

    Found this forum researching for my Mum (I’m a keen veggie/fruit Gardner myself) .
    Was expecting to see someone suggest white oil. Also a safe, organic product and a great home remedy used by gardeners for aeons which may be a cheap alternative to the Eco-oil.
    Any thoughts?

  3. says

    I’ve also had this problem for the past few years on garlic and garlic chives. Lucky my leeks, spring onions and onions dont suffer from them. Last year I tried squirting them daily with the jet spray and squashing them but – no luck – they returned and wore me out. This year I’ve been spraying with Eco Oil every couple of days – they have reduced but not gone. With the price of Eco Oil, it might not be worth it .

  4. says

    I had this problem last year on my garlic and chives and this year they have attacked the garlic chives as well. Apparently they like damp conditions. I find pyrethrum works well, particularly if you get an infestation early in the season before the ladybirds are around much.

  5. Anonymous says

    We had this problem 2 seasons ago on our garlic. I reluctantly sprayed with pyrethrim when I realised no beneficial insects were going to help. Unfortunately I must have left it too long, and the garlic collapsed. when I tried to harvest what was left it had turned to mush

    I haven’t had them since, thank goodness

    Cheers Kim

  6. Elyssa says

    I had some a few years ago on my chives. Surprised the hell out of me as I’d never heard of them before – I didn’t even bother to look closely for a few days as I thought it was dirt. Double checked when the rain didn’t wash it away, and had to Google. I knocked them off with a white oil mix and luckily haven’t seen them since.

  7. says

    Pest management is such a struggle in organic farming, made only worse by the massive tolerance for the strong pesticides that the big monocultures have generated. In Nicaragua some farmers use a solution of boiled red chilis around the base of plants to deter insects that climb stalks. It worked to get the ant infestations out of our tomato roots. I’m not sure, but I think it can be applied to leaves in a lower concentration. Generally it’s used as a preventative measure. Maybe worth a try for aphids?

  8. says

    Great news everyone. The little buggers have reduced in number by over three quarters, with some plants showing no infestation at all. I will still give them a follow up spray on Thursday just to make sure, as it has rained quite a bit over the last few days which tends to wash off the eco-oil

    Gav x

  9. says

    Will have to check my garlic. Don’t think thay are infested. However today I noticed black aphids on my plum and apricot trees. Not sure what to use as both have set fruit now. Any suggestions?

    • says

      use a basic pyrethrim spray. It will not harm the fruit and has a very short lifetime breaking down very quickly. Focus on the new growth because that’s where they will all be. You may have to repeat in four or five days to get rid of any stragglers.

      Also check for ants as they farm the aphids for the sweet juice they produce. You can get collar guards or treatments for the trees to prevent the ants climbing the trees and bringing more aphids.

  10. Sharon Bailey says

    Hi Gavin

    Blast! I too have noticed them on my garlic in the past few days. Never had them before. I have been squashing them, will monitor and see how it goes.


  11. Andrew says

    We had these critters two summers ago. They basically wiped out our chives and killed off our tree-onions (aka Egyptian walking onions). Must admit, I didn’t try the Eco Oil, but to be forewarned is to be forearmed, so I know what I will do if they show up this year !

  12. says

    The exact same thing has happened to my garlic. Yesterday I was looking at it and contemplating spraying oil. This is first for me too. Thanks for the timely post Gavin.


  13. says

    Wow I have never seen black aphids. I wonder if they are a cooler climate insect. I had aphids on my roses but I noticed there was also a lot of lady birds too. Two days later the lady birds had gotten rid of all the aphids. Good luck it would be awful to loose all your garlic.

  14. says

    I had the same problem last year and used the same solution, if you didn’t treat your garlic there is a high likelihood of the aphids actually killing the garlic.
    Interestingly I had Russian garlic in amongst the affected garlic that showed high resistance to black aphid.garlic is a true wonder food and I wish you every success with it.cheers with a beer Pete

  15. says

    that eco oil is interesting… might have to have a look at it, for the desperate times.

    I sprayed our apple tree leaves with euc oil spray (bit of euc oil at the bottom of the sprayer, filled up with water). Ditto the hairy caterpillers. neither aphid nor hairy caterpillar liked it!

    I won’t use it on ‘food’ (direct) plants though iykwim or near blossoms etc and I am wary of it because I don’t want to kill helpful bugs/too much in the soil etc

    euc/water combo sprayer – it’s a ripper for inside the house for those tiny little cockroaches though, as a general spray n wipe etc


Comments build lively communities. Let me know your thoughts, but keep it clean and green! Spam is removed instantly.