Ask Mr. Smarty Plants

You are right to be concerned about your yuccas.  Normally, it is the leaves at the bottom of the plant that will turn brown as the plants grow.  Brown leaves at the top of the plant where new leaves usually emerge is a sign that the plant is in stress.  Since yuccas enjoy dry conditions, my first instinct is that they have received too much water during their winter dormancy and are rotting.  However, it is also possible that they have not received enough water and cannot support their new growth - though this would require very dry conditions indeed.  In either case, you'll want to clip off the brown leaves so that new leaves will have a chance to grow.  If you notice that part of the plant is mushy and rotting, remove that also and make sure that the soil around the yuccas is allowed to dry out between watering.  I really can't imagine that any Yucca species would require more water than the other plants in your Michigan garden, so you may need to occasionally skip over them when watering your other plants, or if you have an automatic irrigation system that waters on a regular basis, you could cap off the sprinkler head nearest the yuccas.  Then, cross your fingers and wait.  In time, it will be clear if the plant will rebound or is already too far gone.  Mr. Smarty Plants will keep his fingers crossed too!  Good luck!

Yucca filamentosa