I have several 3 year old Baptisia australis plants in the same area. All are doing great, but one. I have no clue as to why one of my plants leaves turned yellow (lighter green), compared to the others. I noticed the stalks are brown, compared to the fresh light green of the 7 other plants. The plant flowered this year and it is about 3 feet/3 feet. There seems to be a film on the stalks. Thanks for your advice.