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"Hemlock Not Road-Salt-Tolerant Plant" Q. After doing great for 30 years, the hemlocks that front our property are being ravaged by road salt. The leaves are turning brown. Other hemlocks, away from the road, are doing fine. Is there anything we can do? Each year we add fertilizer for acid-loving plants and otherwise maintain them in good health. This is a new problem. Thank you. A. I'm sorry to hear about the problem with your hemlocks. From what you describe and the fact that only the hemlocks near the road are affected and at this time of the year, it sounds like they are indeed being damaged by road-salt spray. Road-salt spray can do a number on plants near the roadside and particularly certain plants with evergreen leaves or needles like hemlock. Unfortunately, hemlock is not on my list of road-salt-tolerant plants. Some plants are more sensitive than others to road-salt spray and any plants that can't tolerate exposure to it will always be damaged, stunted, and even die in severe cases. As far as what you can do is concerned there may be some things you can do each year that might help and considering you have mature hemlocks in otherwise good condition, it would be worth the time and expense. I'm glad to hear you are taking care of the hemlocks - that's good. Fertilizing, watering, and treating for pests (especially hemlock woolly adelgid) and diseases are the best things you can do to increase the vigor and overall health of your hemlocks. Since you can't move the mature hemlocks away from the road you might want to try putting up some sort of barrier between the hemlocks and the road. That could be a temporary burlap screen attached to posts that you put up each fall and take down in spring or a permanent solid fence like a wooden stockade fence. Either would need to be tall enough to protect the plants from the majority of the spray as best you can. Another idea is to plant a barrier of road-salt-tolerant plants between the hemlocks and the road and that "living fence" could grow taller than any fence you could install. The barrier plants would block the spray from getting to the hemlocks. If you have the room that might be a good long-term solution, but you would still need to erect a temporary burlap screening for a few years until the barrier plants grow big enough to offer adequate protection. Your best bet would be to use plants I mentioned that have evergreen foliage so there would be more of a barrier there in winter when the road-salt spray is present. These include Colorado blue spruce, white spruce, jack pine, Austrian pine, Japanese white pine, and Ponderosa pine. Although I've never tried it, another thing I can think of that might help is to spray the plants each fall with antidesiccant. The antidesiccant coats the foliage with a waxy film and that might seal out the road-salt spray. You'd need to spray the plants before the time when the road-salt treatments start. I spray my hemlocks and other evergreens each fall with antidesiccant for winter protection, but it might work in this situation. Click here to read more about Antidesiccant and order it from Pernell Gerver's Online Store.
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