Sunday, August 21, 2011

Attack of the killer tomato plant - seriously!

One of my favorite things about summer is being able to walk out to the garden and devour Sungold tomatoes right off the vine. The plants are prolific, the fruit is sweet and no cooking is required. What a perfect summer snack!

But today, I discovered the Sungold's dark side.

When I sat on the edge of the raised garden bed and started looking for ripe tomatoes, I noticed something strange: The main stalks of the plant were covered with corpses. Mostly ants, but also a few winged insects here and there.

What the ... ? We don't use ant poison!

Being a woman of a certain age, I couldn't see what was going on. I thought about running inside and grabbing my reading glasses, but decided to grab my camera and macro lens instead. I've been obsessed with photographing ants up close this summer (I'm even selling a few of those shots on my photo site), and that lens totally beats the hell out of wimpy reading glasses.

Here's the graveyard I found:

Every single one of them was dead. If you look closely, you can even see that their little ant bodies have become a bit desiccated.

So here's what I could piece together: Tomato stems tend to be really sticky, and if you brush up against them when you're picking the fruit, you tend to get a bit itchy from the sticky stuff. It looked like the ants had gotten stuck on the plant, like flies on fly paper (or mice on glue boards, which you may recall from last week's post).

But one picture made me think there was a little more to it than that. Check this one out - click on it to see it larger. Do you see what I see?

See how there aren't any droplets around the ant? Looks to me like that ant might've been chowing down on that stuff. This, of course, isn't based on a single shred of scientific knowledge. Mostly it occurred to me because of a photo I took earlier this summer of an ant "milking" and aphid for its honeydew:

Perhaps the plant was poisoning its attackers? That's exactly the kind of thing I'd expect to see, thanks to having read Stephen Harrod Buhner's amazing book, The Lost Language of Plants. The book goes into great depth about how plants may lack the big brains and opposable thumbs that make humans so super-duper awesome, but they get a LOT done by moving chemicals around - including chemicals that harm their predators.

I tried Googling this phenomenon, but got only page after page of angst-filled gardeners wondering how to kill the ants that were preying on their tomatoes - quite the opposite of the situation in my back yard. I love ants. I don't want to kill them.

So, are there any ant geniuses out there with some answers? Where's Mark Moffett when you need him? OK, I'd settle for some uninformed speculation too. Thoughts?

© Holly A. Heyser 2011


Matt Ames said...

Hey there! Andrea says that you should expect to see some aphids soon. Ants bring the aphid eggs up the plant and leave them to grow for a future meal, but tomato plants are poisonous for ants. So the ants die a relaxing, confusing, and agonizing death.

NorCal Cazadora said...

Ah ha!I have seen them tending aphid eggs in that raised bed. And I did read that both aphids and ants like tomato plants, but perhaps that was because ant like raising aphids there, not because they're taking anything from the plant.

Does Andrea have a link to more info? I'd love to read more about this. Is it the sticky stuff that kills them on contact? Or do they eat it and die?

River Mud said...

Remember that tomatoes and tobacco are closely related. Also recall that nicotine is a natural insecticide.

See where I'm going with this? Talk to anyone who has grown tobacco, and they will describe the exact same carnage x 1000. My wife has banned me from growing tobacco at home (vs. the city farm plot) because of the 6 foot tall sticky stems full of dying insects.

I bet this variety of tomatoes has a nicotine-like chemical in it.

Damn True said...

Another data point; Tomato plants secrete a compound called Salicylic acid, which incidentally is the primary metabolite of aspirin. I'm told that the salicylic acid helps the plant defend against pests. Perhaps it's toxic to the ants who likely are on the plant in search of aphids.