Einstein Begonia Browning, Thinning
We have several begonias produced over many years from ongoing cuttings. These are kept mostly inside the house in medium sized pots, well drained, not over-watered. Over the past month they have developed brown spots, some thinning "flesh" of the leaves, and brown holes in the middle. Might this be caused by some sort of insect and what is the treatment you recommend given the information provided? ruch thanks.
District of Columbia County District of Columbia
The spots on your begonia are probably caused by an environmental problem or a disease, but we cannot say for sure from the photos. Your best bet is to simply remove the affected leaves. vw
Although not a degreed horticulturist, my experience might be useful. +/- 20 yrs
ago I began experiencing similar symptoms that I later believed was a fungus introduced from a purchased miniature anthyrium. Within months the disease
killed several rex and iron cross begonias. Other plants including cane and Cleopatra begonias, and abutilon, survived, but developed symptoms per your pix.
I tried different fungicides, but to no avail (fungicides rarely cure disease, at best being preventative). Never did try to have it diagnosed, knowing there are many fungal and related diseases. The good news is that the surviving plants remain decades later, albeit with continuing leaf degradation (which are removed when evidence appears). Unfortunately I know that it will infect other begonias and other susceptible plants, but don't know how long the disease might linger if the carrier plants are removed.
If I had it to do over again, I would have thrown out the diseased plants immediately, then after a 6-12 months rest, purchased a cheap begonia as a canary in the mine, and if no symptoms after a few months, periodically add more (every few months).
Another strategy would be to isolate the infected plants several rooms away, then
hope the disease doesn't spread. Regardless, I recommend that you not leave the diseased plant(s) with your others, even if sentimental or other value.
It may be a painful decision, but please consider the downside and be decisive.
Good luck from a plant lover in AA county.