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Comment by leipert | Hacker News Reader

Interesting, because in Europe we have Cameraria ohridella [0] which wreak havoc on horse chestnuts. The moth replicates like crazy and the only recourse is collecting and burning fallen leaves every year. Luckily it looks worse than it is for the trees, they loose their leaves in August, but by then most of a years photosynthesis is done ( just losing like 17%)

Anyhow American chestnuts are bad hosts for the moths, so a lot of newly planted chestnuts are the American variant.

[0]: https://en.m.wikipedia.org/wiki/Horse-chestnut_leaf_miner

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I hate leaf-miners with a passion. I planted a bunch of citrus trees a while ago, and citrus leaf-miners (https://en.wikipedia.org/wiki/Phyllocnistis_citrella) took a great liking to them. They nearly killed a few of the trees – and this is in a backyard with me attending to them pretty much every day. I hate to think of the industrial-scale agricultural damage these little jerks must inflict on commercial citrus orchards.

But, they seem to be really hard to combat. Efforts to do so (without blanket use of synthetic pesticides) are few, for whatever reason, and anecdotally of questionable efficacy (I managed to track down some pheremone-driven leaf-miner moth traps, which caught a lot of the buggers but didn't really solve anything).

Eventually I figured out that a combination of neem oil and spinosad (Captain Jack's Deadbug Brew) would kill the larval ones, but it didn't kill the eggs and so it would have to be applied every 4 days or so in order to make any progress. I. guess things like that are one of the reasons organic produce is more expensive – some of these things that nature throws at you are hard to combat without using broad-spectrum poison.

A note. Typically non organic pesticides are less broad spectrum poisons but applied in higher concentrations since they "can't" hurt humans

To contrast leaf-miners with other agricultural pests – before the leaf-miners came to town, we also had a bunch of Giant Swallowtail Butterflies (https://en.wikipedia.org/wiki/Papilio_cresphontes) that made their homes in our citrus trees. Their caterpillars never did too much damage, and the annual presence of huge, striking butterflies was pretty enjoyable.

Sadly, I think our (organic) efforts to get rid of the leaf-miners also killed off the butterflies.

I once had the opportunity to talk with some apple growers in Washington (state).

They said that they regularly sprayed their trees with a mix of water and soft detergent early in the season, to prevent parasites and larvae from taking hold. As I understood it, they viewed soap as a simple solution. It was not completely organic and natural, but it helped to keep pests away and it did not seem to cause undue harm to the orchards or the apples.

Interesting, I'll give that a try this Spring! Thanks for the tip. Soapy water in general doesn't seem like something that's problematic as far as eating the oranges later... whether it's technically "organic" or not is secondary for me. I guess that maybe raises an eyebrow about what "organic" means, if soapy water isn't acceptable.

The second year of the leaf-miners, I would go out there every morning and look for affected leaves, just so I could squish the little bugger inside the leaf before it could become an adult moth. It was satisfying, but never really helped.

Horse chestnuts and chestnuts are different genera, though both have "American" and "European" species. The American horse chestnut is often called the "buckeye". The nuts are vaguely reminiscent of each other, but the horse chestnuts and real chestnuts aren't closely related.

This may seem pedantic, but it's sort of important, as real chestnuts are edible (and delicious), while horse chestnuts are toxic to human beings.

You are right and I should have known better. Didn’t read the former article.

In German we make the same distinction, sometimes referring to the real chestnut as Esskastanie (Food/edible-chestnut).

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