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.
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