the microbe universe

Well, everything in life has its ups and downs, even living in blissful Hawai’i. After a fantastic day yesterday, we woke up to find our pals Sabine and Sweetie Pie gone, with only a stinky Sweetie present left amongst the torn up green onions, which were promptly ripped out and composted. Then we hit a bigger bump in the road. Or, more accurately, millions of little bumps in the road. They’re called nematodes. There are estimated to be one million different species of these tiny microscopic worms. Many of them are beneficial in the garden, eating pests that spend time in the soil. But others eat living plant material–the roots of vegetables–and this is the kind we have.

It started a little while ago when we realized the chard was stunted and showing spots on the leaves. This is actually Cercospora leaf spot: when the fungus spore lands on a leaf, the plant kills its own tissue in a circle around the spore to cut off its food, killing the spore. Pretty cool (and you can still eat the leaves). But when a plant is getting visibly attacked by a pest, it’s a sign that the plant was already stressed or weak. Taking a closer look, we pulled up a few chard plants. Back home, healthy chard roots dig into the soil up to 6-8 feet deep. But we pulled them up with ease, revealing tiny, brownish roots–many with big red tumour-like galls on them. At first, we thought it was the season: too much rain could have encouraged root rot, and the shortened day length has been causing everything to grow a lot slower (you’d be amazed by how much the changing day length makes a difference here in winter, even though the change is way smaller than where I live further north).

After some internet research, Connie identified them as root knot nematodes, which we have since discovered are very common in Hawai’i. They aren’t a problem back home, and in fact, Connie has told me that she doesn’t remain on the cutting edge of pest control knowledge. Why? Because she doesn’t really get any pests to speak of anymore–evidence that a biologically diverse system focused on building a healthy soil food web through compost and other habitat for beneficial organisms keeps a natural balance. If harmful nematodes are getting out of hand in our garden, it’s because there aren’t enough other microbes to keep their numbers in check.

The nematodes were bad news because they’re very difficult to get rid of; mostly we can just keep their population down. We’ll do this by adding compost over time to balance out the organisms, planting marigolds (nematodes don’t like them), rotating and fallowing the beds, and planting veggies that are nematode-resistant to starve them of the foods they eat (the kales, broccoli, mustard greens, collards, cilantro, green onions and leeks are doing fine). In the meantime, though, we aren’t keeping up with the ravenous appetite here for salad greens. We thought the poor plants would bounce back from us pillaging them every day now that the days are getting longer, but because of the nematodes we waved our white flag and the cooks bought a crate of Romaine. We’re hosting a work camp here in one week, with around 35 people onsite for ten days. I’m grateful for the plants to have some recovery time.

So to cheer ourselves up, we played science lab today. I took soil samples from all the beds, disinfecting my tools between each one so as not to spread the little worms (we’ll have to do this every single time we use a tool in the garden now). At a friend’s place down the road, we examined the samples under a microscope. We didn’t see as much life moving around in the beds with compacted soil. We saw lots of tiny nitrogen-fixing bacteria in the bed where the clover cover crop is still growing among the plants. These awesome bacteria, which live on legumes, convert nitrogen from the air into a form that plants can use. We also brought some freshly brewed and very lively compost tea. The lactobacillus, a beneficial bacteria, looked like a sausage (or a string of sausages). Zippy little ciliates shot across the slide in a hurry. Long fungal strands were covered in ladder-like rungs. And the nematodes were easy to spot: little worms squiggling around, wrestling with a tiny piece of humus. But we couldn’t identify whether they were the good kind or the bad.

The coolest thing we looked at were some indigenous microbes. Before I arrived here, a bunch of “pristine” soil was gathered from up in the hills. We spread cooked rice in a planting flat, poured unsulphured molasses over it, and laid the soil on top. We’ve kept it covered and moist for the past few weeks as the indigenous microbes feed and multiply. When the rice has disappeared, we’ll make a compost tea from this highly active and locally appropriate microbe universe to help build soil fertility in the garden. In the meantime, our small sample from the mushroomy-smelling, mould-covered tray has showed us there’s plenty of beneficial life in there.

I can’t remember using a microscope since high school science class, and I have to say I never thought I’d get so excited over soil microbes and mouldy trays of rice. I think my biologist roommate will be proud 😉

Unfortunately I don’t have any shots of the microbes, but here’s some lovely sunflowers instead.

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These are some of the bucket-full of edible flowers we harvest every day for the cooks to garnish the food.. hibiscus, calendula, nasturtiums, and.. blue butterfly pea I believe..

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One response to this post.

  1. I read someplace that a vinegar water mix sprayed on plants gets rid of alot of problems

    Reply

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