The effects of various rates of spring- and fall-applied anhydrous ammonia, with and without 2-chloro-6-(trichloromethyl) pyridine (nitrapyrin) on [corn Zea mays] stalk rot, stalk diameter, and yield were determined. Stalk rot from natural infection and stalk rot following inoculation with Diplodia maydis or Colletotrichum graminicola decreased with increasing N rates. Nitrapyrin reduced stalk rot in some treatments; it did not increase yield or stalk diameter. The reduced stalk rot with increasing rates of N and at lower rates of N with nitrapyrin may be due to a continuous supply of N throughout the growing season.