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!
It almost looks like "leaf burn" from excessive fertilizer salts built up on the soil. If it were pests and/or disease, you would see a more uniform pattern on the foliage...such as a "mottled, splotchy" discoloration, leaf drop, and/or an overall "sickly" appearance to the plant. What I see on the photos is an otherwise healthy plant, with some blackened leaf tips on the new, tender foliage.
These are photos of my Pachypodium geayi. This specimen is about 16 in/41 cm tall and growing in full sun. Notice the deep green coloration of the long, narrow foliage, and felt-like undersides. I am using a well-draining bonsai soil with a little bit of slow-release, granular fertilizer. Edit: Further research has revealed that P. lamerei should be a lighter green than P. geayi, so I do not believe there is an issue with light exposure. Check out the "Succulent and Caudiciform Culture Guide" posted in this forum. In particular, click onto the Highland Succulents link and read about fertilization and soil. After reading, you may want to consider a soil change and modifying your fertilization practices.
