OK - that's not a water issue and even if it was, fungicide is not the solution for that sort of problem. Arborvitae tend not get a lot of disease issues but Berkman's blight (Coryneum berkmanii) is one that can do some serious damage. My suggestion would be to take a sample of the affected foliage to your local extension office for an accurate diagnosis. If confirmed, they should suggest control measures but typically it involves pruning out the affected tissue now and then spraying to control development of the fungal spores, usually in early fall. A preferred fungicide would be a copper sulfur application, not so much the Neem oil. But get a confirmed diagnosis first before attempting any other home health care :-)) FWIW, as long as drainage is good, it is pretty near impossible to overwater Thuja orientalis......one of its common names is swamp cedar. Typically, inadequate watering is more of a culprit for arborvitae problems.

It's not you - it's the plant! They colour brown in winter (especially the parts exposed to the brightest light). They will revert to green when the weather warms up a bit more. Personally, I love conifers that turn, say, gold or violet in winter, but I'm not so keen on the ones that turn brown - to me they just look dead!

Fertilizer probably. If not, you have a blight/root agent or foiliar. You can snip it all off just below infected foliage then I'd spray the whole darn thing with a fungicide this year and wait to see what happens, that's assuming you're the type of person who wants to wait and see if the plant can recover but this looks like another uphill battle of sorts with no end to it. Personally, without hesitation, I'd remove it immediately and start working organics back into the soi and replant something new, next year. Beneficial Mychorrizae at planting time as well as while working in the organics would surely be a strong recommendation. Dax

Nate, I'm really ko because of the strange characters what gardenweb makes. Kekfesto - or Kékfestő- is the correct name. This means "painting blue", an old hungarian job to prepare clothes in cooking blue colors. Finally Toth Gyula prepared the O series grafts of my all new cultivars. Next week I plant them in a topsecret place as a mother plantage. I hope really, some of them may loved trees later. Zsolt