My poor buddleia leaves….

Dear Readers, my poor benighted Buddleia plants (two wild-type monsters in the front garden) have both been afflicted with leaf and bud eelworm. One of my readers suggested that this was what was causing the strange variegated appearance of the leaves last year, and it’s taken me until now to follow up. Dear oh dear. 

Eelworms are actually microscopic nematode worms. We hear a lot about these invertebrates in connection with garden bio-control these days, but they can also be parasites. These extraordinary little creatures have colonised every habitat on earth, from the deep seas  (where they comprise 90 percent of all the organisms found) to the poles. We have no idea how many species there are, with estimates varying from 25,000 to over a million. Suffice it to say that wherever you go there are probably thousands, if not millions, of nematodes, mostly minding their own business but sometimes turning up as parasites of plants or animals, including us.

The Buddleja National Collection website (I have no idea whether it’s Buddleia or Buddleja, but let’s not call the whole thing off just yet) suggests that the critters in my leaves are Aphelenchoides ritzemabosi, and there might be another species in the bud, A. fragariae. Here is a photo of the former.

Photo by By Jody Fetzer – http://www.forestryimages.org/browse/detail.cfm?imgnum=5026046, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=17505099

In the spring, adult worms swim up the stem of a plant – they can only do this if there is high humidity. Well, I don’t know about where you live, but here in East Finchley we’ve had more precipitation this year than in any year I can remember, so no wonder the buddleia is looking shoddy. Once they reach a leaf, the tiny animals enter the leaf via one of the stomata (the breathing pores of the plant) and happily set about eating the leaf, laying eggs and generally having a good time. At the end of the season the worms go into a quiescent state and remain in the dead leaf after it falls, waiting for another lovely damp spring so that they can launch themselves into action again.

One way to detect eelworms is said to be to take some affected leaves, tear them into tiny pieces and leave them in a glass of water, at which the worms may abandon ship and be visible at the bottom of the glass. I’ve done this with a few leaves, so I’ll let you know if I manage to spot anything.

During a warm spell, the entire life cycle of the leaf and bud eelworm can be completed in ten days, which gives you some idea of why they might proliferate so easily and quickly. Furthermore, they attack a whole range of plants, including strawberries, chrysanthemums, anemones, creeping bellflower, rhododendrons and about thirty other species. The RHS suggests that you burn all affected leaves and buds. Well, at this point that would involve setting fire to my entire shrub. However, I think there’s hope. I have been noticing a lot of blue tits and sparrows in both of the buddleia just lately. They might be eating the aphids and ants, of which there are also quite a few, but they do seem to be pecking at the discoloured areas of leaf. Do they sense that there’s a bit of protein in there, I wonder? The birds have been spotted pecking at the leaves of horse chestnut that are scarred by leaf miner moth too, so maybe they’re gradually recognising a new food source. Fingers crossed, because spraying for this particular nematode would do no good at all (not that I’d ever do such a thing).

So, hopefully the buddleia will be resilient enough to cope with yet another pest. It’s no fun being a street shrub in a relentlessly urban area, with climate change messing up the seasons and pollution adding to the stress. I always think it’s a miracle that things do as well as they do.