Hello! I have a Madagascar Palm (Pachypodium lamerei) that I have had in various pots for the last 20 years. It is about 9 feet tall and grows about 8 inches/yr in it's current environment, which is a patio that receives a few hours of direct sunlight each day. I am in So Cal where the summers are warm and dry and the winters are moderate w/ no freezing. For the past several years, many of the new leaves at the top of the 2 trunks turn black and curl up at the tips. Any idea what might be causing this? I have tried fungiced but I don't really see any improvement (at least not for long). I've had this plant for 20 years and don't want to lose it! I have attatched 2 pictures of the leaves. Thanks in advance!