Have you stuck your fingers in the soil around your arborvitae periodically to know what the soil moisture conditions are? It really does sound like a root problem. If the berm is very narrow, soil in the berm could be drying too quickly. Otherwise, it's likely too wet. The only way to know for sure is to to look at the condition of the roots (healthy roots should be firm and have tan-brown outer covering, with creamy-white interior; rotting roots would be more uniformly brown and perhaps very soft) and to investigate the soil drainage. Arborvitae can tolerate periodic soil flooding, but not lengthy, prolonged wetness. I have seen some instances of Techny and Emerald Green arborvitae planted in low berms over wet, heavy clay soils in the Chicago area appear quite healthy for 1-2 years and then fail over the next couple of years as their root systems extend beyond the berm into the surrounding wet clay. Do you live in a subdivision built after the 1960s? If so, then poorly-drained, compacted clay soil may likely be the problem.

the brown one is dead .. the off color ones in the middle are dying .. by the time those are gone... whats left??? start over ... it doesnt matter what they are ... they are arbs ... ohhhh... wait.. congrats on new house ... and garden .. they are conifers... as in producing cones.. but they are also trees... they NEVER stop growing ... it just a matter of decades and annual growth ... though some might slow down in old age ... ones that claim to be shorter in 10 years.. just grow less.. each year ... i am confused by the pix.. which show a large yard.. then the plants.. i suspect.. yours is the small yard behind ... remove them ... and for a thin version.. consider degroots spire at the link ... IF you get single leader plants .... they can be about 18 inches wide when 10 feet tall ... but they will never stop ... and they have no snow load issues ... of which.. you didnt tell us where you are.. for other options... but these old tree dont look like heavy wet snow ever collapsed them ... good luck ken Here is a link that might be useful: link

I have to backtrack a little and explain that when I planted the first set of trees, I was a COMPLETE newbie. I did not even have the soaker hose down at that point. I was watering them by hand about once a week thinking that would be enough. The soaker hose is that flat fabric kind and I've got two of them connected to a "Y" at the edge of my house...one length that goes down the side of the house is 25 feet, the other length goes toward the yard 50 feet. Together they make a 75 foot run and I read that a length under 100 feet should not be an issue where equal pressure is concerned...am I wrong? There is no "incline" along the length where the water ever has to go uphill, that is an optical illusion. From where the water enters the hose it only goes downhill slightly. I've been using this soaker hose all summer and it seems to do the job well, although I had to use it every day since I did not have time to put mulch down until this fall. I am thinking the reason the first batch died was from obvious lack of water before going into winter and then drying out by spring. Also not having mulch might have been a factor since we got down to -5 last winter. I have a hunch that the drying winds knocked out most of them, since my few survivors were the ones next to the house where they are somewhat protected. Which leads me to another question... What do you think of Wilt-Pruf? Could I prevent some dessication by using it? I was going to go with burlap but that is an awful lot that I would need to wrap...do these even need protection from wind if they get enough water before winter? I think in the spring I will move the one arb with the dead branch to the end of the line and replace it so I can keep the height I have going in that area (I need it there! I don't think want a window in my hedge..haha).

You will probably not prevent bagworms, but you can control them. Bagworms are the larva of a moth that lays the eggs that then hatch to make those distinctive bags. Control is by physically removing the bag early on, spraying with "Bacillus thuringiensis - Kurstaki" early on or later with a Neem Oil product, maybe Spinosad, or maybe a pyrethrin based product. What might be causing the other problems would be at best a wild guess since numerous things could be the cause, ranging from physical injury to some other insect pest to a plant disease. The Bayer product is an extremely toxic poison that needs to be handled with great care and should only be used as an absolute last resort.