Bottom Of Flower Is Decaying

Question

Top of flower is fine but the bottom half is decaying

Answer 1

This could be a number of things, depending on the type of flower and pest present, as well as the conditions around the plant. If it isn't part of the natural senescence of the flower, then you might suspect bacterial infection. This can, usually, be corrected by a fungicide:

https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm