Isolation Required To Ensure Top Eating Quality Of
KALAMAZOO, Mich.— Stan
dard sweet corns are no longer the
common choice of consumers
buying sweet com at fresh mark
ets and roadside stands. With
improved sweetness, flavor and
the ability to retain their sweetness
longer, shrunken-2 (sh-2) sweet
corns are pushing their way into
markets.
Sh-2s fit well in the sweet com
mix of taste-conscious consumers
and profit-oriented retailers, but to
feed those markets, growers need
to take steps to ensure high quality
of sh-2s.
“Sh-2 sweet corns don’t mix
well in the field when other types
of com are planted nearby,” said
Steve Marshall, sweet com breed
er,
“When sh-2s are pollinated by
other types of sweet com or field
com, the end result is field, or
dent, com types.”
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Xenia, the influence of pollen
on the kernel expression, causes
this condition. In sweet com, xeni
a affects endosperm, the part of
the kernel that consumers like to
cat.
“With the first bite of dented
com, you know that something is
wrong,” said Marshall. “The com
will taste starchy, almost bitter.
Xenia increases starch and
reduces sweetness in sh-2 sweet
corns.”
Standard sweet corns express a
recessive “sugary” su-1 gene,
accumulating about twice as much
sugar as most field corns, mostly
in the form of sucrose. If standard
sweet com, with its recessive su-1
“sugary” gene, is pollinated by
field com with the dominant Su
gene, cars will be starchy rather
than sweet.
‘The problem with sh-2s is that
they arc more closely related to
field corn than to other sweet
corns,” said Marshall. He explains
that sh-2s contain both a sh-2 gene
and the dominant Su gene, also
found in field com. When sh-2
corn cross-pollinates, the domin
ant Su gene masks the sh-2 genes
for sweetness, and the result is
starchiness.
“When this happens, kernels
have all of the characteristics of
field com. They’ll have a white,"
floury appearance, dryness, and
starchy texture,” he said, “and will
taste awful when eaten.”
Xenia also affects kernel color.
Within sweet com color, the gene
for yellow dominates, while the
white gene is recessive; xcnia
affects color when the dominant
yellow hybrid pollinates the reces
sive white hybrid. Pollination
from a yellow com causes yellow
kernels to show up in a white
sweet com variety. You can see
the results shortly after pollina
tion, as kernels start to develop,
said Marshall.
Because of greater demand dur
ing the main season, roadside
stand operators and retailers often
receive higher prices for sh-2
corns, according to Marshall. Iso
lating sh-2s will ensure growers
that the com they’re selling is
worth higher prices.
“Sh-2 sweet corns will live up
to their genetic potential if grow
ers isolate to reduce the risk of
xenia and follow other proper cul
tural practices,” said Marshall.
“Growers can isolate by space,
time, and/or wind direction.”
In Florida, growers had serious
problems with isolation when
sh-2s were introduced several
years ago, because they planted
experimental strips in the middle
of standard sweet corn fields.
“They expected sweeter c~ rrl but
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Corns
got dent instead. Now, most grow
ers plant sh-2s exclusively,” said
Marshall. \
To isolate by space, Marshall
recommends that growers plant
sh-2 corns at least 350 feet away
from any other type of com.
“Isolation by distance is diffi
cult in the Midwest, Northeast,
and mid-Atlantic areas, because
so many types of corn arc
planted,” said Marshall. “One
grower may plant two or three
hybrids on just a couple of acres.
In such situations, a growers must
isolate by time.”
There are two ways to isolate by
lime maturity of the hybrid and
date of planting.
‘The greatest risk of xenia is
between sh-2s and other types of
sweet com,” said Marshall. “The
risk of cross-pollination bctcen
sweet com and field com planted
at the same time is minimal under
normal growing conditions,
because sweet corns usually
mature in 60 to 80 days and field
corns mature in 90 days or more.”
To isolate by maturity, growers
should plant varieties that arc at
least 10 days apart in maturity,
said Marshall. “An early standard
sweet com can be planted at the
same time as a midscason or late
sh-2 sweet com with little risk of
xenia under normal growing con
ditions,” he said.
“Growers planting sh-2 'and
other types of sect corn with the
same maturity should isolate by
planting lime. A standard sweet
com and a sh-2 with identical
maturity should be planted at least
10 days apart,” said Marshall.
The same rules for isolating by
space or lime apply for planting
white sweet com near yellow or
bicolor varieties.
“Wind direction also can be
used to help isolate sweet corns,”
said Marshall. Sh-2 com should be
planted upwind if it must be
planted near field com.
“Consumers have high expecta
tions for sh-2 corns because of
their improved flavor and strong
abilities,” said Marshall. “Grow
ers should do everything possible
to ensure that their sh-2s meet
buyers’ expectations.”
PARC Completes
Research Facility
EASTON, Md.— The PARC
Institute of Easton, MD has
announced the completion of a
new turkey research facility.
According to Dr. James
McNaughton, director of research,
“The facility has been designed
with maximum flexibility to meet
the research needs of the turkey
industry.”
A large number of floor pens
are available for work which requ
ries well-replicated research con
ducted under growing conditions
that approximates commercial
turkey housing.
A specific area has also been
included in the facility for
research that requires replicated
floor pen work under sanitized
conditions.
In addition to the two floor pen
areas, battery cage capability is
also available.
McNaughton said, “Although
most of (he research conducted for
clients will be nutrition and health
related, the facilities arc fully cap
able of performing breed evalua
tion, management practice, and
other types of research.”
A brochure is available that ful
ly describes the research capabili
ties of the PARC institute. For
copies, write to the PARC Insti
tute, Inc., P.O. Box 1161, Easton,