My guess would be low humidity. Might also be as you say a disease, but I can't diagnose it from here. You might check with your local county extension office. They have the ability to make scientific tests. Is it a Florist Gloxinia? They are not technically known by that name anymore, but are now Sinningia speciosa (if that's what you have!) You might be more successful finding information by that name. There are gloxinias too, to keep beginners confused, which I have probably managed to do anyway. Sorry! My head hurts and I can't think straight!

If the leaves are older and smaller, they will yellow and dry naturally which is all right.

The drying bud could by a lack of humidity or possibly Botrytis Blight. Did you notice any fuzzy mold on the buds?

I would suggest removing the buds so spores will not continue to spread if it is Botrytis blight. Cure is with Benomyl but if you have only a few plants, just take off all buds affected.

Nancy

I have moved Gloxinia in my office and watered it on Monday, Wednesday and Friday giving her adequate amount of light. On Monday or even during weekday, the flower elge began to brown and get older before it fully bloom. Is it also cause by humidity? There is no air con during weekend. In such a case, what is your recommendation to maintain the normal life of flower?
Thank you & Best regards
Yok Fong

Yok -

a combination of high humidity and high temperature ages the flowers. I keep mine in a fish tank because of the low house humidity, but if I close the lid - that's exactly what happens to the flowers - so i need to keep the lid half-open.

If your office is not airconditioned on weekends - it can be really hot - you can try to move your plant off the window for weekends - or just take it home. You can probably get some more heat tolerant plants for the office.

Good Luck

irina