• The Low Down

Don’t dodder about devil’s shoelaces

Devil’s shoelaces sucking the life out of its photosynthetic neighbour.


Given the scorching-hot climate where the embodiment of evil is purported to live, you’d think the devil would wear flip-flops or sandals, but rumour has it he wears Prada. Lace-ups, it seems.


“Devil's shoelaces” is a name applied to dodder (Cuscuta spp.), a native parasitic plant that looks more like creepy orange spaghetti than a plant. Dodder is known by a slew of titles including wizard’s net, strangle-weed, witch’s hair, and hellbine. As these names suggest, dodder has a sinister reputation, which is no surprise, as parasites generally inspire collywobbles, rather than cuddles.


The leafless, ghostly, tentacle-like dodder really ramps up the squirm factor. Research has shown it is able to recognize which plants are around it by sniffing them out. Every plant gives off a unique mix of compounds, making it easy to tell cilantro from tomatoes with just one whiff. Not only can dodder distinguish one plant from another, it can sense which is more nutritious and will move toward that one with great precision and attack it.


In the words of Consuelo De Moraes, an assistant professor of entomology at Penn State who studies parasitic plants, dodder “…exhibits an almost animal-like behavior.” It’s enough to make you afraid to stand still in the garden for long.


Because it lacks chlorophyll, dodder needs to vampirize green plants to live. It can parasitize most dicot plants, but is especially fond of tomatoes, potatoes, azaleas, legumes, dahlias, petunias, and ivy. Once it reaches a victim, dodder inserts root-like filaments called haustoria into the phloem vessels of its prey and begins sucking out nutrient-rich sap. Needless to say, this is not the best thing for its victims.


Julie Kikkert, a specialist with the Cornell Vegetable Program, says dodder can reduce commercial carrot yields by 30 per cent to 90 per cent. She also notes that dodder produces a tremendous number of seeds, which can remain viable in the soil for possibly up to 60 years. This means that crop rotation is not a practical way to manage this pestilence.


Dodder control is a challenge, often requiring several years. If you find this beast in your garden, hand-pull it as best you can. Then prune out and destroy all plants that it has parasitized. At the very least, prune plants two centimetres below the point where dodder has penetrated.


Ideally, a pre-emergent herbicide (one that inhibits germination) could help, but dodder must be listed on the product label. There is some evidence corn gluten meal, which is considered nontoxic, can inhibit germination. It’s available at some garden centres and online.


The other meaning of dodder is to amble or totter feebly. If I ever hear someone refer to me as a doddering old man, maybe I can frighten them with a few facts about devil’s shoelaces, the ominous orange-tentacled, veggie-vampire — if I can remember the details by then.


Paul Hetzler is a former Cornell Extension educator. Although he dithers a lot, he seldom dodders. He lives in Vals-des-monts.