Flea beetles, nasturtium, alyssum & marigold



climbing nasturtium

FLEA BEETLES, NASTURTIUM, ALYSSUM AND MARIGOLD

by Denise Motard

What is the link between all of the above you may wonder?

Here’s one I believe I found the hard way this past summer.

Every year I grow lots of climbing nasturtium (among other climbing annuals) to cover my green chain link fence. It’s not only beautiful till the first hard freeze, but the whole plant is edible. The flowers add a bright color to salads, contain as much Vitamin C as parsley, and the green seed will add a peppery taste to dishes. They can also be pickled as a caper substitute. Nasturtium would also have some medicinal properties and stimulate hair growth.

I never had any problem with pests or diseases in my nasturtium (I’m growing them since 2006). Until last summer.

It’s hard to find a garden without alyssum – usually the standard white variety. It’s very useful for borders and blends well with flowers of various colors. It attracts small pollinators and is nicely fragrant. They bloom all summer till the first hard freeze, sometimes even beyond (for those on the south side of my house).

I never had any problem with pests or diseases in my alyssum for the last 6 years. Until last summer.

Marigold (tagetes) are also a standard annual in gardens. Blooming with a profusion of rich yellow, orange, or dark red-orange flowers, they’re available in various sizes and will keep blooming till the first hard freeze as well. They can also be used as a companion plant to repel some pests in the veggie garden thanks to their aromatic scent, especially the foliage. 

I always grow marigolds, some in the veggie garden as a pest repellent and some in flower beds. Except last summer when I didn’t grow any.

Flea beetles are small, shiny black coleopters that jump from leaf to leaf when eating or disturbed. Yes, they eat leaves. Lots of them. They like young, tender leaves, and specialize in particular families of plants, like the cabbage or radish family. If you see tiny holes in your young radish or cabbage leaves they’re most likely the culprits. Their attacks are most severe during dry weather, and sunny days.

Every year I grow some radish, arugula, and either red cabbage, broccoli or Brussels sprouts. I always had some young leaves with holes in them from flea beetles, but the plants were able to keep growing and the damage was minimal. Until last summer.

Since I never had any significant damage before from flea beetles in my nasturtium and alyssum, it took me quite a while before realizing what was going on. By then there were zillions of them, so many that I could hear the noise they were making when jumping on the nasturtium leaves!! I had to pull out all of the now flowerless alyssums, the mustard (which had more holes than leaf left) & all of the nasturtiums except three plants around a post. I was able to ‘save’ those from total annihilation by inserting thyme, peppermint & flowering tobacco stems into the plants as a repellent, and hand wiping the leaves early in the morning or late at night when the beetles were less active. It worked, and those plants were able to recover and bloom till the first hard freeze as usual. And the wet September must have helped too.

Climate change? – Last summer was especially dry on the island – June had three times less precipitation than normal, and July too was very dry. From what a researcher on climate change said at the last Nature PEI conference, we should expect dry summers and wet falls as the new trend on the island and plan accordingly for farming and gardening. Did last summer dry weather trigger a flea beetle invasion?

I also found the following – nasturtium and alyssum are both part of the same plant group as radish, mustard and cabbage.

Will I include marigold as a pest repellent in my future garden plans? You bet!! As for the weather, we can partly mitigate the effects of drought bouts by using mulches for example.

Any comments and/or suggestions are welcome.