Question
i've had a corn plant for about 13years. it was very small then and is quite tall now. usually has very green leaves on it,and healthy looking, but now  some leaves are turning brown and yellow. it has sat in the same location this whole time.the corner area of the living room next to a large picture window. i water it once a week and fertilize  once every 3 months. i use fertilizer sticks.any advice would be helpful.

Answer
Doug,

From the info you gave me I can't tell you what the problems are. It soulds like you could be overwatering it. I can tell you that Corn plants hate to be overwatered and if you water thoroughly once a week is too often. The soil needs to feel very dry on the surface before you water it again.  They also hate water with chlorine or flouride in it. The fertilizer sounds fine and so does the lighting.  If you don't think the water is the problem tell me about anything that has changed in the last 6 months.
Good luck.

Darlene