Leaf Spots (fungi – Cercospora nandinae, Glomerella cingulata): Small, circular spots develop on the foliage. Lesion is brown-to-dark brown with reddish halo. Fungicides not required. Sanitation will help reduce foliage infection.
Ring Spot (virus): Light green or yellow, irregular rings occur in leaves. Plants tend to be smaller and low in vigor. Destroy diseased plants. Propagate from healthy plants.
Iron Chlorosis (nutrient deficiency): Foliage becomes light green and finally a greenish yellow. The veins tend to remain green. Foliar applications of iron sulfate or copperas are usually effective if several applications are made when leaves are forming. For mid- or late season corrections of a severe deficiency apply iron chelates such as Geigy 330 Fe (Central Texas) or Geigy 138 Fe (West and Far West Texas).
Cotton Root Rot: (See the section on Cotton Root Rot)
Root Knot Nematode: (See the section on Root Knot Nematodes)