My two kale transplants quite suddenly started having discoloured bottom leaves and dropping them.  Why?
Quite suddenly, my transplanted kale was not doing so well. What happened? (c) Julie Leung

Pests in the Garden: Reality Sets In

My transplanted kale was doing great, then bottom leaves started wilting. Other Kale in next row is fine. What am I missing?” I tweeted to Donna Balzer, the No Guff Gardener, and one of my instructors in Grow Food Calgary.

Nearby kale rows started from seed which are still healthy
Nearby kale rows started from seed which are still healthy

Across cyberspace, she took one look and made her diagnosis: “Root maggots- common in everything in cabbage family- yikes“. Over the next few hours, we conversed in 140-character soundbites across Twitter. She told me it’s a long story, but the problem starts in the soil (like everything, it always comes back to the soil!). I asked how I could fix this and prevent it from spreading to the adjacent rows of kale which were a different variety. They were doing well and I didn’t want them to succumb to the pest. Donna’s advice was that I needed to dig the entire plant and the soil around it, put it on a piece of paper to confirm the plant was infected, and toss the plant and the soil around it. There was no salvaging the infected plants; there was way I could get rid of all the eggs otherwise. I also found out that nematodes, which I’d heard about in previous Grow Food Calgary classes as a biological control that can be purchased, would have worked — but it was way too late for them now. Happily, over time, my soil would get so good that it would naturally have nematodes.

Finding Root Maggots … and Pupae

So my husband and I went back outside after the kids had gone to bed and we started digging. I figured if the wilty-looking kale plants indeed were infected with root maggots, we should deal with them as soon as possible to try to prevent them from spreading, so we could try to salvage the other kale plants a mere foot away in the next row.

Cabbage fly pupae found in the soil surrounding a wilty kale plant
Cabbage fly pupae found in the soil surrounding a wilty kale plant

We had 2 transplanted kale plants that were in differing stages of wilt. The first one, in the front, was in worse shape than the second one, in the back and closer to the fence. The first one had more wilted and discolored bottom leaves. The day before my tweet, it had dropped 3-5 leaves. They had quite suddenly turned yellow and fallen off the plant. When we dug up the one that was in worse shape, we didn’t find anything near or on the root. But we found things that looked like brown rice scattered sparsely in the soil around the root. I manipulated them between two garden spades. They were hard and felt like cellulose, bark, or plant material. They did not seem living. It was possible that they were kernels or husks of some tree which had been left in the soil. A quick look on the internet indicated these could be pupae. I pressed hard — really hard — on one of the brown-rice-like kernels between my two spades. Finally it gave way to something white, juicy and wet inside. I figured this was an indication whatever was inside had been living. These were indeed pupae.

We put that first plant, its roots, and the soil we had dug up (along with several pupae), into a plastic bag and moved onto the 2nd wilty kale plant. It looked to be in better shape. But when I got its root up out of the ground, I knew why. I found maybe 20-30 white maggots crawling in and around, all over the buried stem, roots, and clumps of dirt. It was both a grotesque and slightly stomach-turning sight, yet somewhat interesting — it felt like when you see something disgusting but for some reason you can’t turn your head away. Maybe I’m a freak, or maybe it is the biologist in me that was somewhat fascinated in watching so many of them wrapped around the stem and roots, and undulating.

Root maggots crawling on and around stem and roots from infected kale plant
Root maggots crawling on and around stem and roots from infected kale plant

Stomping in my Gumboots

We put this second plant stem, roots, maggots, and soil into a bag. Then we stepped on the bag with our gumboots over and over until we thought the maggots were squished. After all, we had decided we were not going to (gasp!) throw soil that had to have some beneficial living organisms (beneficial bacteria, etc.) and nutrients into the trash. For dumber or wiser, we decided we would spread it onto our front lawn in a bid to feed the grass, where there are no brassica family plants to destroy. We figured that should be far enough away from the garden that any maggots that weren’t stomped to death (or pupae that hadn’t had their contents squished out) could not crawl their way back to the unaffected kale.

And it was then that I understood why the first plant had no visible maggots or eggs, but was yet in so much worse shape than the second plant that was crawling with maggots. The maggots had already finished feeding on the first plant and had transitioned into pupal stage. The bulk of the damage had already been done on the first plant, and the pupae were either going to overwinter or hatch adult flies. The maggots were just getting started on the 2nd plant, and not enough time had elapsed for the full damage to show.

I May Pay for Being Loathe to Throw Away Anything

Now, I don’t know if this is silly beginner gardener thinking, but after we had mourned and disposed of our infected kale plants, we inspected the soil to look for and remove any escaped pupae, maggots or eggs. For the eggs, we weren’t totally sure what we were looking for, but we didn’t think we saw anything suspicious left in the soil. Seeing nothing, I decided to re-use the now-empty space by transplanting various tomato seedlings into the area. My reasoning was – tomatoes are decidedly not in the brassica family, so hopefully even if we’ve missed any eggs in that section of the soil, the maggots that hatch won’t be interested in feeding on my tender tomato transplants. Then again, if we’ve missed anything and they hatch and realize there isn’t kale right there, they may move a few feet over and start feeding on my healthy kale plants! Or, as per this very helpful page I found from Alberta Agriculture (a day too late), the adult maggots that may have been missed by our stomping feet in the sparse bits of soil on my front lawn may travel (up to a few kilometres!) and back to my backyard garden to find my unaffected kale plants. Oops.

Sometimes it’s not great to be a newbie gardener. But I guess this is what trial and error and learning is all about!

Record Scrrrrrrr-atch!

This Canada Day long weekend marked for me a quite blunt re-introduction to reality. In the last month and a half, I’ve been merrily lounging in my new discoveries — about “making” good soil and its benefits, planting things I’ve never planted before (kale! lettuce! shallots! radishes!
carrots! microgreen peas! dill! cilantro!) and watching in delight as they sprouted and grew, getting out into the yard and discovering the joy of tending my garden. But this weekend, it was like the needle on the record of my idyllic gardening soundtrack was suddenly yanked across the turntable and a megaphone announcing one of the harsher realities of gardening took the place of all the carefree songs. Ah yes, this is why the constant debate about pesticides still abounds, why commercial gardens (and some personal ones!) still feel a need to use them.

Next Up: Pests Get the Better of Me in my Indoor Garden

This post was about pests in my outdoor garden. In my next post, I’ll be writing about pests in the vegetable and herb plants in the house. The pests inside the house have finally forced me to take drastic measures, as I’ve harvested, reset or transplanted to the outdoors much of what was growing inside. But in and among the “pests” indoors, I discovered an ally. More on that soon!