I have been having this Yucca Cane for about 4 months now. I live in Illinois and have this Yucca plant near the patio door on the west side. So sunlight is not a problem (as long as it is not cloudy) and I water it very sparsely once every 3-4 weeks. It has started developing yellow wilting leaves and there are some brown spots on the remaining healthy green leaves and they too show signs of wilting too! The stem seems to be firm. I worry that this plant is dying and I want to save it. Any suggestions on what might be the problem?