Breeding for disease resistance is a major component of our sweet corn breeding program. We have active programs for five corn diseases where we inoculate and select or screen for resistance.

The diseases we work with include:

• Maize Dwarf Mosaic,
• Northern Leaf Blight,
• Stewart’s Wilt,
• Common Smut and
• Common Rust.

Our (common) rust resistance program is quite active with disease nurseries in both the summer and winter. We also have a greenhouse program for rust resistance. Hybrids and inbreds are screened for rust resistance in these same locations. Rust resistance ratings are also done on our hybrids in the various trials we have in the United States and throughout the world.

Breeding for rust resistance has its challenges, as the biotypes of rust are in a state of flux. Up to two years ago single gene resistance using the Rp1d gene gave very high resistance to rust in the United States.

Now, new virulent races (biotypes) have appeared and in some areas Rp1d is not working so well. In other areas or earlier in the season Rp1d is still effective.