Help!

[cactinewbieph]

Guys can you tell me what is happening to them?

[esp_imaging]

"What is the brown stuff in the center? How can it be cured or can it be removed?"

I assume you mean the scarring where something has been eating it. Do you have a slug or snail problem? Especially on damp evenings?

"One of it's leaf shriveled up and one just dropped. What is happening? How can I avoid this?"
Older leaves will gradually shrivel and die, as newer leaves are produced. Leaves on this plant are only loosely attached and are a means of reproduction. The separated leaf is capable of growing roots and then generating a new plant.
If the plant has got healthy roots, it can probably take quite a bit of water during the summer. This will speed up growth and reduce the loss of older leaves. You can only take this approach so far, too much water will lead to killing the roots and/or stem rot.

[cactinewbieph]

Thank you for the reply.

[greenknight]

Agreed on both. The damage on the first one will be hidden before long.