Hi Dave -
I haven't made a compost tea from horsetail, but have made a "real" tea (more properly an infusion) for use as an antifungal treatment. We just simmer a handful of it in
water, then let it cool and spray on plants. It seems to be effective on powdery mildew, maybe not so much on rust. And so far nothing seems to help with leaf curl on peach
trees, but I'm hoping that a high-bacteria compost tea might be the ticket and horsetail in the blend sounds like a good idea.