Question
Leaves are drying up (brown/rust in color) from tips inward.  Also some browning on tips of new growth.  I don't think I am underwatering or overwatering.  Is this a disease?

Answer
Hi Marilyn:
Leaf tip browning can be caused by many things. Often it is an unfavorable root environment rather than an infectious disease related- that is, the roots are not functioning correctly. These plants like most others , like a well drained soil to grow in. If there is much peat or peat moss in the mix, then it may hold too much water, a common problem with interior plants. Over watering is a common "misnake". This can lead to root rot. When I water my interior plants, I generally wait until they almost start to wilt, then carry them outside and pour water into the container until it comes out the bottom. Giving them a through soaking. Let drain. Then wait until it starts to wilt again. Keeping a little water put on them everyday can be a big issue.So,watering imbalances can sure cause the tips to brown.  Another cause can be when the roots get real tight in the pot.  You can ease the root ball out of the pot to check that. They need plenty of room.  You may need to "fluff" up the roots a bit and put in a larger diameter pot. Sometimes if the plant is relocated and it gets a sudden change in temperature or light, it may brown up too.

So, I'd focus on the roots first, then look at temperature/light thing next.

Regards
Steve