By Kyle Asplund, Itasca County SWCD
With scent/fear-based browse repellants such as Plantskydd becoming the “new wave” in animal browse repellants, Mike Oja and I set out last fall to see if the large move from bud caps to Plantskydd is the right move. We decided to try a small study on one small tree planting. Keep in mind that this was only one trial in one location of Itasca County. 
The location was a 5 acre upland area near Smith Lakes with a very high concentration of deer.
The location has had a history of browse even when trees have been protected with bud caps. The trial was comprised of 260 two year old White Pine split into two blocks. Block #1 consisted of 130 White Pine that were bud capped in the fall of 2007. Block #2 consisted of 130 White Pine that were treated with one application of Plantskydd at the same time in fall of 2007. Any previous browse on the trees was taken into account.
Follow-up was done in early May of 2008. The results were as follows: 5% of White Pine terminal buds that were treated with Plantskydd were found to be browsed; whereas, 75% of the White Pine terminal buds that were bud capped were found to have been browsed. Many of the bud caps were found to be lying on the ground (pulled off) or actually eaten through. It was clear in this situation that the Plantskydd outperformed the bud capping.
Even though this was just an informal study, it has convinced this one landowner to use Plantskydd next year. This trial compared the effectiveness of bud capping to Plantskydd; however, there are also other animal browse repellents on the market today such as taste/smell based chemicals (Bitrex) and physical barriers such as fence or shelters. These products have also been proven to be effective and may be taken into consideration in high browse situations as well. In the end every browse situation must be taken into consideration by itself to determine what is best for that particular site for that particular tree.
This article appeared in the September 2008 issue of Itasca Woodlands. It is reprinted here with permission. For much more information on protecting your seedlings from deer, visit the section on protecting your seedlings on our Tree Planting page, which has links to two other repellant studies. You can also read about protective tree shelters in this discussion thread.
What has worked, or not worked, to keep the deer off of your seedlings?
A question: How well does Plantskydd survive fall rains? How long does it need to be on the bud before it is washed off by fall rains? Does the length of time after application before a rain determine how well it works through out the winter?
I have found that using plantskydd under good or ideal conditions works well. However, when extensive rains fall after the product is applied, even if it has 48 hours to dry and has been applied according to label instructions, it’s effectiveness becomes limited relative to the amount of rain it receives. We have had extensive fall rain the last 2 years after the product has been applied according to label intsructions, and the majority of the trees have been browsed on several hundred acres. I also believe, that the trees get browsed in the spring, just before green up as a result of extended time since application.
When using bud caps, it is important to get some of the needles stapled to the paper which gives the bud cap more holding power.
I’ve had the same experience as Dave. An early spring application of repellant is needed. I use a repellant with latex in the fall, after leaf-off, to make it hold longer through the rains and winter. I then use Plantskydd in the spring, because I think it can be applied at colder temperatures than the latex repellants, and I worry about the latex affecting bud growth later in the season. I’ve also had many buds with budcaps broken-off the seedling by deer. I will try stapling more needles into the caps, as Dave suggested. BTW, MNDNR tested some repellants on jack pine a few years ago and found that some of them burned the pine. I’ve never had that happen.