Ants are burrowing under my brassicas!

jchokey(8)May 2, 2012

Two weeks ago, one of the kale plants in my garden bed wilted slowly and died. It was a fairly recent transplant so I didn't think anything of it-- that sometimes happens Then a second one collapsed a week later. Today, I noticed that a collard plant next to these two-- one that had been doing quite well until just days ago-- was wilting and collapsing as well! Clearly something was up!

Closer inspection revealed that the base of the collapsing collard plants was swarming with small black ants. They weren't climbing up it to the leaves at all-- and I didn't see any sign of aphids on the leaves or stem. They seemed to be digging down around the base of the collards, towards the roots. Moreover, there appeared to be ants all over the base of the nearby kales/collards as well-- even the ones that still seemed healthy. Again, they seemed to be digging down into the soil around the base of the stems.

I've something of a novice gardener, but have never before heard of ants attacking plant roots themselves. My guess is that there maybe something else down there eating the roots-- and the ants are going after that other pest..... but I did a bit of poking around in the soil around the collapsed kales and saw nothing but more ants.

Any thoughts on what's going on or how to protect the remaining collards/kales in that bed?

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jean001a(Portland OR 7b)

Probably not attacking the roots.

More likely, the ants are using the ready-made "trails" roots provide. As a result, water runs off rapidly rather than being absorbed by the roots.

    Bookmark   May 2, 2012 at 11:58PM
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Thanks Jean: I appreciate the prompt response-- and it's great to hear from someone else here in PDX!

Your explanation makes sense. The ants seem to have been doing some serious tunneling, right around the stem/roots. I don't think they're attacking the roots themselves.

Still, I guess I'm wondering if there's a way to tell whether they're just using the roots as 'trails' as you say (in which case, just getting rid of the ants should solve the problem), or if the ants are just there to prey on some other critter attacking the roots.

I say this because I saw some posts on another gardening forum by folks having what seemed like an identical problem ( and in their case, the ants seemed to be a ssymptom rather than a direct cause-- they were there to prey on some type of underground, root eating maggot. That said.... that gardening forum is for the UK-- and I don't know if the same factors could be an issue here in PDX....

    Bookmark   May 3, 2012 at 2:17AM
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ken_adrian Adrian MI cold Z5

never heard of ants adversely affecting plants in this manner [not to say its not possible.. i am talking probable] . .. unless there is some hive of 20 billion ants under your garden generating scorching heat .... heard of that.. lol ..

frankly.. all you have told is is that there are ants... how about giving us some more facts to work on ...

what is your watering protocol

what did you do to the soil in prep for your garden ... what is your native soil.. what did you add .. etc ...

the odds are you .. as a novice.. did something .. rather than jumping to disease ... of which.. it is simply not that common ... unless you bought diseased stock ... which i doubt ...

we need pix.. to get much further with this ...


    Bookmark   May 3, 2012 at 7:42AM
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jimr36(5b CO)

It would be very helpful to close / high-resolution pictures of the "ants". Sometimes views up close show the pest to be a different creature altogether.

    Bookmark   May 3, 2012 at 1:02PM
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Per Ken�s request, here�s some more information on the bed/planting/plants/watering history:

This is taking place in a 4�x�4x1� raised bed (which we call Bed #3) that was established and planted for the first time last summer for a fall crop. The original soil mixture in it was 3/4 Black Gold Coco Mix (planting mix with coconut fibres) and 1/4 mixed organic compost from Teufel− the same mixture as in our other beds. Last year�s crop in the bed included a mix of root crops (carrots/radishes), brassicas, (not kale or collards, though), celeries and curly endive. (We have been using the �square foot gardening� approach, which is how we had so much in there.) On the whole, the bed produced beautifully (except the celeries− they never took off) through the fall (with occasional additions of blood meal for nitrogen) and the endive/chard ended up producing through the early winter�. at which point it lay dormant for about two months. We did have quite a few aphids on some of the brassicas (for which we eventually found a solution) and saw a couple of cabbage worms, but other than that, we had no real pest or blight problems in the bed last year�.

In late March we amended the soil with a few cubic feet of compost from our own pile (it was quite broken down), and some mixed fertilizer from our local organic farm store (a mixture of feather meal, bone meal, etc.) We planted the bed in early-mid April− mostly with non-brassicas− but also with transplanted kale/collard starts that are now failing in conjunction with the ant infestation. (FYI: We hadn�t initially planned to put any brassicas in this bed this spring, since there had been quite a few in their last year− but, a friend gave us some lovely looking collard and kale starts, and as beds #1-2 were mostly planted and bed #4 was not yet there, we planted them here thinking, "Well, we�ll see what happens." We did also put a few collards in bed #2, by the way− but more on that later�.)

Once planted, the bed was under a plastic cloche for about two weeks since we were still having pretty cold nights. We watered maybe only twice a week, because the cloche kept moisture in pretty well. In mid-/late April, things started to warm up and we took the cloche off. (BTW, Kale #1 had failed before the cloche came off, Kale #2 shortly after. The other kales appeared to be taking off just fine− and the collards were kicking butt in terms of growth). At this point, we got a couple of kale starts from the organic nursery to replace the failed ones− and those seemed to get established well enough. And the collards continued to do just great− they had started at about 2-3" tall and are now maybe 6"-7" with strong sturdy stems. The other plants in that bed (mostly root crops− potatoes, parsnips and salsify, to be precise) all appeared to be fine as well.

Anyway, since the collards had been growing great for a full month− it seemed pretty weird to me yesterday when I noticed the one collard drooping over, while the others all still looked perky. That�s when I noticed the ants around the base. It was then that I noticed that all of the other kales and collards in that bed also had ants busy around their bases and digging in/around them. (This includes not only the kales/collards are friend gave us, but also the ones we got from the nursery to replace them.) None of the other plants in that bed appear to have the ants− not or any drooping/wilting problems. And, I should note, we�re not (yet) experiencing this problem with the plants in any other beds as well− not even the collards we put in bed #2. They are ant-free and wilt-free.

So, to summarize: the problem is only occurring with the collards and kales in this one bed. It�s not occurring with the other plants in that same bed. It�s not occurring with the brassicas in our other beds (at least not yet− *knock on wood*)

    Bookmark   May 3, 2012 at 1:57PM
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OK, I'll take some pics of the wilting collard and the ants and post those− I probably won't get to that till the weekend though.
Thanks for the help on this, btw.

    Bookmark   May 3, 2012 at 2:01PM
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Apologies for the strange nonsense characters in my above posts. I had typed the text in my e-mail program and then cut-and-pasted it here-- and it looked 100% fine in the preview. I don't know what whent wrong.

    Bookmark   May 3, 2012 at 4:33PM
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jean001a(Portland OR 7b)

Well it's like this -- although ken hasn't seen ants create enough channels to funnel water away from the roots of a plant, I have.

Further, it sounds like you have premium soil conditions for ant housing -- elevated, so is well-drained, also warmer than ground level soil which right now in Portland, is downright soggy!

And the soil in the raised bed is also light & fluffy, easy to create channels in, but sturdy enough to retain the channels rather than allowing them to collapse.

    Bookmark   May 3, 2012 at 7:46PM
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rhizo_1 (North AL) zone 7

This is fairly common ant behavior, something that I have witnessed pretty frequently in my consulting activities.

    Bookmark   May 3, 2012 at 10:41PM
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I have, on occassion, seen ants doing something similar and usually they are building a nest there. Since ants only build nests where the soil is dry a good soaking might well encourage them to move.

    Bookmark   May 4, 2012 at 8:28AM
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Thanks for the additional input, Jan, rhizo_1, and kimmsr.

The theory of the ants nesting in there because it's dryer, warmer, etc. also fits in with the fact that we've recently had to repel a minor ant incursion into the house-- that's something we experienced last April/May as well during the particularly rainy/soggy spring.

I'm still going to dig up the most recently collapsed collard this evening and will examine the roots carefully for subterranean pests or grubs-- but maybe it just is the ants themselves. I'll take pics of what I see, regardless.

    Bookmark   May 4, 2012 at 10:28AM
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OK, I have an update.

I dug up the the most recently collapsed collard and examined the roots and the soil around it (again, there were ants swarming around the base). My wife and I thought it looked like something that eaten away the outside of the main root-- from just below the soil surface down, along with a lot of the root filaments. You can see a picture here:

This seems to lead me a way from the 'it's just tunneling ants' theory and back towards the underground pest theory However, I didn't see anything appeared like an obvious pest on the root or in the nearby soil-- (I was kind of expecting subterranean aphids clinging to the root or seeing little wriggling grubs or something). If they were there, they were either really small, or concealed themselves, well, or just not something I could recognize. There were, though still lots of ants.... and there still are around the other kales and collards.

Any thoughts?

    Bookmark   May 5, 2012 at 12:21PM
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I also dug up a kale that was starting to wilt-- and which was ant-plagued at its base. Again... nothing obviously pesty but the roots (this was a smaller plant) appeared eaten away to the point of non existence (just a stringy main root that looked like the outside had been eaten away-- from just below the surface downwards.

I tried taking a close up of the soil around the root remants, but I'm afraid this was the best I could do with my camera. (Any closer up and it was blurry).:

    Bookmark   May 5, 2012 at 12:26PM
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Hi! I came across this forum posting because I am having the very same problem! Ants are burrowing under my kale and brussel sprouts and systematically making my plants wilt and then die. I think we have the same problem and I'm curious as to what you did to make them go away? I would rather not put any insecticide on my garden.


    Bookmark   June 3, 2013 at 12:08PM
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This happened in my garden this past week. I found ants collaring my kale plants and killing them. I got out my bio Neem and dabbed the bottom of the plants and the next morning thee ants were gone. In Neems defense it is an organic insecticide and if used correctly works very well with minimal impact and a breakdown rate of 1-2 days. It is practically non toxic and the only thing you really have to worry about is accidently getting it into water as it is slightly toxic to aquatic life and not spraying it openly in the air when bees are out and about. I am fond of using a paintbrush for controlled applications and spraying at the end of the day when bee activity is down.

    Bookmark   May 14, 2014 at 12:01PM
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I also live in PNW and had same problem. So did a coworker of mine. They were under my carrots. They would pour out every time I harvested one. I had put little ant traps around my garden. Seemed to help. I also sprinkled cornmeal around too and they just ate it up.

    Bookmark   May 15, 2014 at 11:02PM
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I have the same problem with ants, but I have to disagree with some of the posters (at least in my case). The ants are indeed eating the flesh from the base of the stem just below the crown.

They are doing this to my dwarf blue curled vates kale, but not my red russian or dinosaur kale. The dwarf vates actually has a very tender stem that I don't trim out when eating it, so this does not surprise me that the ants would be able to feed on it.

I also saw a YouTube video about this (in which it appeared to be dwarf gates) in which the exact same thing was happening and he zooms in close so that you can see it.

Just search for "Ants on kale plants eating stems"

This post was edited by wild_forager on Sun, Jun 1, 14 at 18:37

    Bookmark   May 30, 2014 at 8:58PM
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small lid, 50% borax and 50% common sugar, place around where ants are....workers take borax back to queen, no more ants, 2 or 3 oz pure orange oil to gal of water, soak mound around 9 or 10 am when ants are active...they don't move to start another mound, they die...i had to do one mound twice...the indian....note: twenty mule team borax at walmart...

    Bookmark   July 7, 2014 at 1:56AM
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