Pale bleached older leaves: Aerangis species

Hi all,

I have two species that have puzzled me. I first noticed older leaves getting pale and chlorotic mid 2021. I initially suspected a nutrient issue, and it still very well could still be that, as my 2021 growing season I wasn’t entirely consistent with fertilization. Starting in February 2022, I’ve been regularly using MSU at 0.25 tsp per gallon to provide roughly 50ppm Nitrogen and water mounted plants every other day. PH is adjusted to 5.5-6

I started fertilizing more regularly as the Aerangis distincta was growing it’s leaf first new leaf of the season. The leaf started nicely green, which was encouraging, but now that it’s matured and new leaf is emerging, it too is starting to develop a pale character. It’s as if there isn’t enough nitrogen or chlorophyll to go around.



1. pale older leaves 2. First leaf of the season - started growing in February was nice and green now demonstrating some fading 3. Current leaf that’s growing


Aerangis arachnopus showing similar

Any advice? Is 5 months of supplementation not long enough to see results? At one point I also suspected too much light, but I don’t believe this is the case because they are growing in shade, and even the shaded parts of the leaves are pale. I started supplementing with a bit of magnesium a few weeks ago. However, with these species being generally low-nutrient requiring plants, I’m a bit puzzled by all of this. Am I being inpatient and should carry on as is?

 

Thanks Ray - I was hoping you would chime in.

I use reverse osmosis water. The filters are due to be changed, but my last TDS reading showed 8ppm so I'm hoping it's not that. I started some epsom salts 2 weeks ago so probably not soon enough to see results. I previously tried some Calmag, but honestly found it very challenging to gauge how much to use and I saw some burning so I stopped. Any recommendations on amount of epsom salts to use if watering daily/every other day? No pesticide use for over a year.

EDIT - I just read your helpful site which recommends 20-50ppm Magnesium. With my 50ppm N MSU, I'm probably only getting 7ppm of magnesium. I will be supplementing with epsom salts continuously immediately.

Thanks Marni - I'll switch things around and see how things go. I have another newer bag of MSU that I will try. It may very well be the same batch, as we buy it in bulk as a society, given that it's not economical to purchase it in Canada. I'll do some digging to see what brand we've been using to keep track, if anything.

 

Thanks Marni - I have a newer Aer. distincta that is much younger that's fine, but I've only had it for about 6 months. However, I have this happening with Aer. arachnopus and a bit with Aer. biloba as well, all of which are older (>4 years) plants in the collection, which makes me feel it might be a related nutrient issue.

Good to know!