Scale insects, not a disease. The black stuff on the top surface is called black sooty mold, and it's a fungus which grows on the excess sugars secreted by the scale insects, which are the white circles on the underside of the leaves. Kill the scale insects, and the fungus part will go away by itself.

The best treatment would be a systemic insecticide like imadicloprid, which I assume is probably available in Israel, unless it's been banned for some reason by your version of our Environmental Protection Agency. I would check with a local garden center and see what type of systemic insecticides they sell. Second best approach would be horticultural spray oil. This however might burn the foliage and further stress the tree.

If you do use the sytemic insecticide, don't use the leaves for cooking for at least six or eight months, to give the tree time to purge the insecticide from its system.

Hope this helps.

wow. I'll look for the spray. Is there a better season to spray in? Like maybe not rainy season, or during our super hot summers or something? I never use the leaves from this tree, as my healthy one gives all I could use and much more, so the 8 month hiatus is no problem. Will it bother the carob next to it? Does this kind of scale affect other plants? I've never used this kind of insecticide before - so I'm back to asking newbie questions! Thanks Batya

Batya, sorry I didn't respond sooner, I don't check out the herb forum too often, mainly go to vegetables and fruit and orchard forums.

Um, no, you can use these systemic insecticides any time of the year, doesn't matter. Here in the US, they are sold as a soil drench, very easy to use -- just dig a small hole near the trunk of the tree, pour the stuff in, let it soak into the soil, fill in the hole, and then water it in well. Rain won't be a problem, in fact, the manufacturers recommend a good soaking afterwards to help move the compound into the plant.

These scale insects probably won't bother anything except other bay laurel, since most species of scale are pretty host-specific. Some scales do have a bit wider host range, but odds are, if your bay tree is heavily infested already, if these bugs were going to bother the carob, they would already be doing so.

Hm, carob, bay laurel, I'm so envious! I bet you have olives and palms there, too. I have an olive and some palms and some citrus and a bay tree -- all in pots, all come indoors for six months of the year.

Dennis
SE Michigan

Thanks Dennis. Olives, palms, anything you'd think of in a Mediterranean climate. Since most of the posts on GW are in the US and in cold climates and deal with freezes and snow etc, I have to adjust for my climate. I'm going to check out the southern/california forums to get better info. I'm hopefully going to plant my bulbs today, and hope they don't rot in the wet soil for the next four months! Batya

Batya,

I have a similar problem, so will need to follow the same treatment. What systemic insecticide did you use, or did you find some morew eco-friendly?

Keith