Home  > Preharvest  >  Hybrid Selection for Corn

Aflatoxin: Plant hybrids that have adaptation for southern U.S. growing conditions. There are no hybrids that are resistant to aflatoxin contamination, but there are differences among hybrids in their degree of susceptibility. The differences are primarily associated with traits that make the corn more tolerant of environmental stresses. These traits include a general adaptation to high temperatures and drought, as well as resistance to both ear-feeding and root-feeding insects. The desirable traits of adapted hybrids are tight husks that cover the ear tip and a hard endosperm that maintains kernel integrity.

Hybrids that are prone to loss of kernel integrity should not be planted. Under conditions of heat and moisture stress, some hybrids are more prone to splitting of the seed coat. The splitting can be longitudinal and lateral (known as "silk cut"). This naturally-occurring wounding increases the risk of contamination.

Transgenic hybrids with insect resistance will help reduce contamination, but can not totally prevent it, since the fungus can get into the ear without insect wounds.

There has been no recent, systematic evaluation of hybrid susceptibility to aflatoxin in Texas. Such work has identified hybrids that are highly susceptible to contamination. Optimally, evaluations are made over two years, in different locations, because the response will vary because of different environments.

Fumonisin: Differences in fumonisin accumulation have been identified in hybrids in the midwestern U.S., but there is no information for hybrids planted in Texas. Resistance to Fusarium ear rot is correlated with lower fumonisin levels, but fumonisin contamination can occur in the absence of visible ear rot. Husk cover is one trait thought to be associated with fumonisin resistance. In other growing areas, insect resistance, including that in transgenic hybrids, is associated with lower levels of fumonisin, but there is no information for Texas growing conditions. Fumonisin contamination can occur without previous insect damage to ears.