If you can post a picture, that would help. Brown spots can be a sign of a fungal infection or lack of moisture. Things like Cercospora Leaf Spot or Anthracnose , for example. If you notice yellowish to rusty brown pustules, especially on the undersides, then you may have another fungal infection called rust .

Yellow leaves problems come in two flavors: (1) the leaf yellows out but the veins stay green or (2) the whole leaf yellows out. The first is a sign of iron chlorosis {{gwi:1014232}} and you need to acidify the soil so the plant can absorb the iron naturally found in the ground. Soil Acidifiers or products that add iron will get rid of this problem for a while. If whole leaves are yellowing then there could be several reasons, from watering issues, some form of plant stress, or root rot (accompanied by some wilting), etc.

If you cannot post pictures, you can always take a sample in a tightly-sealed plastic bag to any local nursery, university or Agr. Extension Service.

Luis

Luis,
From the information you provided, it appears that it is Cercospora Leaf Spot. Thanks for your help.

I planted a pink diamond about a week ago and I too have yellowing leaves in the center of the plant. Otherwise it looks healthy, no wilting, perky flowers. Do you think I may be overwatering? I have very good drainage.I planted it in a combo of good topsoil and bumpercrop. I am hoping it is just shocked and that it will recover. It is such a beautiful plant, I just love it. It has been very hot, could that affect it? I would hate to lose it. Vignewood