Short post today — Linda appears to have transmitted her illness electronically over a couple of thousand miles — Thanks Linda!
I was reminded yesterday that it’s almost time for gardeners to start worrying about winter deer damage. With that in mind I thought I’d share with you my favorite research article on the subject. It’s a little paper by Michael Fargione and Michael Richmond and published about 18 years ago. You can find it here.
This paper attempts to establish how repellent bars of soap are to deer and comes up with some very interesting conclusions. The first thing you should know is that no one type of soap appears to be better than another. The second thing you should know is that soap does appear to stop deer from feeding around the soap — but the best you can hope for is a radius of protection of about a meter from the bar of soap itself — Can you imagine what that would look like if you were trying to protect the lower limbs of a large tree? And finally, bar soap appears to attract voles. Based on my reading, and my limited experience, I’ve found that almost everything that people say repels deer does repel deer — human hair, peeing around a tree, predator urine, dried blood — the issue is how long these repellents stay effective and how effective they are when the deer get really hungry. The most effective commercial deer repellents tend to have “putrescent egg solids” in then (rotten eggs) — I once had a graduate student who needed to protect some hazelnuts from deer and she found that a mixture of a few eggs (2-4) mixed in a quart of water and sprayed onto the trees worked pretty well — and no, the eggs weren’t rotten. This mixture should be sprayed about once every two weeks if possible.
I agree, Jeff – lots of things will repel deer unless they are really hungry. When we lived in Buffalo, we would see deer eat EVERYTHING, because there were too many deer and not enough predators. I’ve suggested that people plant “deer food” as a way of keeping the deer out of other plants. (And I asked the blog fairy to fix your link and to make you feel all better soon.)
The effective deer repellent is a good fence. I encircle susceptable shrubs with 4 ft tall chicken wire staked far enough away so the deer cannot easily push against it and eat the greens anyway. I agree that nearly every repellent works for a while, but only a while.
I recommend a small but bloodthirsty dog.
Works for us!
There’s no argument that tall fences, or short fences close enough to plants that deer can’t jump them, are most effective. However, hardly practical in many areas, and quite unattractive. In the Washington DC area we have as severe a problem as anywhere, and we have found that spraying with a repellent monthly is effective in the worst circumstances, even when we have rainfall well above average. I have no question that this is a satisfactory short term solution to a problem begging for a long term answer.
Has anyone studied the effectiveness of wireless zappers? They’re one foot high stakes with 2 AA batteries inside that deliver a mild shock (feels like a static electricity zap) when the deer sniff or lick it. A scent lure is stuck on the top, but it doesn’t lure them in from far away, they have to stumble across the stake in their browsing. But when they do, they’ll stay away from the immediate area, not just the one
plant. I’m using them around a meadow and garden area. So far so good, but does the shock fright “wear off” like the repellant effects do? Will the deer learn to avoid the stakes and eat the nearby plants? Anyone looked at these?
check out wirelessdeerfence.com
I did an internship at Longwood Gardens in PA a while back. One of the jobs of the interns was to put up an electrified fence every evening after the garden closed in the month leading up to the tulip display. (The ground crew took the fence down every morning.) Apparently it was very effective when bated with peanutbutter for many years. The year I was there the deer discovered they could jump over the fence and get to the yews and tender bulbs. It was to the point there was discussion of closing the garden down for a day so that a hunting party could be organized. I never did here how that turned out.
Oh deer! We’ve got nothing of the sort down my way, it must be a headache for horticulturists in North America. On the rotten egg front, I wonder if the Indian cooking ingredient ‘black salt’ might work as a cheaper alternative to egg spray? Black salt, despite what its name might suggest, is actually pink and has a strong eggy sulphur smell to it. Worth a try, I reckon. The poor deer – they’re only doing what comes naturally!
Foy, what you used was called a baited electric wire. I used them in Georgia to protect experiments from deer — they’re very effective — but can’t be used around residential neighborhoods (obviously). And, as you noted, once the deer figure it out — that’s the end.
After trying all the remedies mentioned except the fencing in a public garden, I found Tree Guard to be the only effective long term solution. Long lasting but a little difficult to get out of the sprayer because of a lumpy latex base that continually clotted. May have improved sprayability in recent years.