I'm assuming you're growing the "European Blueberry" or "Bilberry" (Vaccinium myrtillus), rather than one of the North American blueberries like Highbush blueberry (Vaccinium corymbosum). The "European Blueberry" grows wild in Scotland, Wales, Ireland, England, Alpine countries, Poland, and northern parts of Russia. So I assume it likes cool temperatures! It may just be too hot for it in Greece right now. The American Highbush blueberry likes swamps and bogs, so I don't think you're overwatering, unless the "European Blueberry" is vastly different than the American one. The U.S.A. blueberry is also frequently found in shade in the wild, so you may want to be sure yours is not getting full Mediterranean sun. I would see if you can move it to a cooler spot. If you test the soil and it's too alkaline, you can acidify the soil with any type of plant food made for hollies and that sort of shrub, but I'm not sure what this type product would be called in Greece. Here we use something called "Holly-tone". Hope this helps...

Thanks Dave and Howel. My father-in-law follows The Garden Master system http://thegardenmaster.com/. I got some hand me down 5 gallon bags from him but they were not holding up well so I bought what I thought were 5 gallon nursery pots on Craig's list. They turned out to be 3 gallon. He feeds his once a month but it is a special concoction he got from the system. I guess his stuff is extra potent and that 2 gallon difference is significant. I will up the foliar feeds to weekly and see if that helps. I was not aware of problems with using granular fertilizer in containers I will definitely look into that. I was leery of using a synthetic fertilizer precisely because I wanted to establish some good bacteria and was afraid synthetics would be a detriment to doing that. The rest of my veg looks good but maybe I will run into similar problems as they mature. Thanks again for the help!

You've got to kind of wonder about the training of a 'master gardener' who believes fungal problems are only directly related to rain and lack of summer heat.......There are many causes to fungal issues and heat and dryness can certainly be contributing factors, just as much as damp, rainy weather. Heat and dry conditions are primary contributors to the development of powdery mildew, for example. It is impossible to be certain without an accurate diagnosis, but the symptoms resemble those of verticillium wilt, which is a soil borne fungal pathogen (no water or mild temperatures required - it just exists). It typically will affect only selected portions of the tree, leaving the rest looking fine. Until it fails completely :-(( Take a sample of the affected branches in to your local Cooperative extension office for diagnosis and ID. If it is VW, there's not much you can do other than remove the tree.

This looks similar to what I am seeing on my tomato plants. (Here is my post about it.) We did have couple of cold nights here in MA. So may be it was cold winds. My plants are outside for last three weeks though. So they are hardened off ..