Why are leaves falling off of my Prickly Pear cactus?

Question

I just moved into a new home in Phoenix, AZ, and now have a lot of cacti to tend to. I do not know their care history, or how much/how often they are watered.

One of the largest Prickly Pear cacti is dropping its leaves (pads?) at a seemingly high rate. Is this a sign of over watering, under watering, a lack of pruning, or something else entirely? Some of the pads look wrinkled, which I'm told can mean either over or under-watering.

Here is a photo of the cactus

Here is a photo of the place where the most recent leaf-bunch detached

Here is a photo of the broken segment on the ground

This most recent break (the one pictured here) occurred about 24 hours ago.

Answer 1

My experience with the prickly pears I have here in Texas (natives and cultivars) is that the wrinkling is typically due to under-watering. The seed pods (tunas) will also wither in low water conditions (I have yet to get my own tunas). Under-watered pads will appear thin. Over-watered are going to appear fat. I have yet to over-water prickly pears. I don't think it is possible in a well draining soil.

I also see structural failure - groups of pads falling off. In my cases it is due to overgrowth. Overgrowth like this is probably quite natural - pads will readily grow as new plants - they're by far the easiest cuttings I've tried. Ie. pads get broken off or "branches" break, put out roots, and you have a new plant!

You also have corking which indicates some age, although I've seen this on some varieties after only a year or two. I don't think I've seen spotty corking like you have though. I don't think it is due to disease (the rest of the plant looks fine). Could be due to sunlight watering, or insect bites in the distant past (the cork would be a natural healing response).

re. pads or leaves. Botanically speaking, the pads are actually elongated stems. The true leaves are the spines!