Journal archives for November 2019

November 22, 2019

Stuff on Box

Recently I've been finding weird stuff on a few small patches of Box (Buxus) on campus. Box, as far as I know of, is very commonly planted in towns and cities in the Northeastern US, so I wouldn't be surprised if these critters were just as common as their hosts.

Box Sucker (Psylla buxi) forms strange somewhat globular galls out of the terminal leaves. They're fairly indistinct unless you know they exist, which they become fairly easy to pick out. The galls appear like slender clubs at the ends of branches, with leaves near the galls themselves often being malformed as well. This was the first Box gnawer that I found, finding it pretty much instantaneously once I could locate a Box bush.

Box Blight (Calonectria pseudonaviculata) is less conspicuous and to be honest I didn't know exactly what it looked like until looking for a while. It appears to form tan patches with darker borders in the center of leaves, something that might be a bit difficult to pick up unless you have a healthy leaf nearby to compare it with. The most important symptom appears to be dark lines on twigs, although i haven't checked for this yet. This seems to be reasonably common on the type of Box that's in the patch I looked like, although I've heard that newer plantings are of a more resistant variety (species) that might also be more resistant to other Box bugs. I'm not 100% sure this is the correct species for these symptoms, but for now I have my observations of this set to this binomial.

Box Miner (Monarthropalpus flavus) is probably even less conspicuous, forming faint yellow dots on the leaves. It's probably better to call this a gall than a miner, since it doesn't seem to make conspicuous mines from what I can see and is even a species of Gall Midge. This species seems to be common in the box patch I looked through, just not quite as conspicuous as the Suckers nearby.

Box Mite (Eurytetranychus buxi) is probably the least conspicuous of the four Box gnawers that I could find, although like the others it can stand out pretty well once you can locate some. These mites cause the leaves to become mottled with pale dots that are sometimes in pale lines from feeding on the leaf juices. If you compare leaves with mites with leaves without them, the differences can be quite conspicuous. Flipping over the leaf reveals an almost fibrous texture underneath (for the lack of a better word, photos show it better) that isn't present on healthy leaves. There are also often small red orbs on the underside of infected leaves that are probably the mites themselves. This one seems to be more widespread, occurring even on the newer disease resistant Boxes I found in some other places.

There's other animals and fungi that I haven't seen yet that also infect Box. These include a rust (Puccinia buxi) and another leaf blight that appears to turns the leaves entirely brown with black dots (Hyponectria buxi). If anyone knows of anything else on Box that I didn't mention please let me know, I'll be eager to look for them.

Posted on November 22, 2019 08:01 PM by astrobirder astrobirder | 5 observations | 2 comments | Leave a comment