This works like a damn as a deer repellant.
1 tablespoon of baking powder
1 egg yolk
1 litre of water
The older and rottener and stinkier the better. I've been using mine for 3 years now. Mix up all you want, put in a spray container, let it sit in the sun for a few days, then spray away every now and then when you think of it.
Organic, won't hurt the plants, trees etc.