Cotner, Sam

Hartz, Tim

Longbrake, Tom

McCraw, Dean

Menges, Terry

Parsons, Jerry

Peavy, W. S.

Roberts, Roland

English

Texas A&M University

KEYS TO PROFITABLE SWEET CORN PRODUCTION
FOR WHOLESALE AND DIRECT SALES MARKETS
Dean McCraw, Terry Menges, Jerry Parsons, Roland Roberts, W. S. Peavy,
Sam Cotner, Tom Longbrake and Tim Hartz*
L-1464
Sweet corn is grown predominantly as a fresh
market crop in Texas in the spring and summer.
Reported acreage harvested declined from 2,200
acres in 1976 to 1,800 acres in 1980 because of the
expense of controlling earworms and the rising cost of
hand harvesting and handling. Production of sweet
corn for direct sales outlets and local farmers markets,
however, has been increasing steadily in all areas of
the state. Per capita consumption of sweet corn has
remained at 8 pounds.
Production Areas and
Seasonal Movement
Sweet corn is grown statewide with the largest
acreage located in two major areas: the Rio Grande
Valley and the Winter Garden-San Antonio. Small
acreages for local markets and direct sales outlets are
concentrated around urban areas and on truck farms
throughout Texas. Sweet corn production in cotton-
producing areas is hampered by heavy pressure from
the corn earworm.
The Rio Grande Valley acreage is planted from
early January through March and harvest begins in
mid-April. Seeding begins in the Winter Garden in
late February or early March and continues into April
in San Antonio and the Coastal Bend with harvest
beginning the last of May. Growers on the Upper
Coast and in Central Texas and East Texas plant in
March and April and begin shipping in early June.
Heaviest shipments occur in May and June.
*Respectively, Extension horticulturist-special programs, Exten-
sion horticulturist, Extension vegetable specialist, Extension
vegetable specialist, Extension horticulturist-vegetables, Exten-
sion horticulturist, Extension horticulturist-vegetables and Ex-
tension vegetable specialist, The Texas A&M University
System.
Climate Requirements
Sweet corn is a warm season crop intolerant of
frost. The rate of growth and maturity is fastest with
high day and night temperatures. Optimum average
monthly temperature is 68° to 72° F. Few varieties
make significant growth below 50° F. The optimum
soil temperature range for germination is 75° to 95° F.
Few seeds germinate when the soil temperature is
below 50° F. Sweet corn growth is dependent on the
time of exposure to air temperatures above 50° F. The
time required to mature sweet corn from seed varies
from about 65 to 90 days depending on the variety
and temperature conditions.
Sweet corn is a short-day plant, and the tassel of
most varieties develops faster at day lengths of fewer
than 12 to 14 hours. High temperature before harvest
does not affect kernel sugar content. After ears are
harvested kernel sugar is converted to starch at a rate
which increases with increasing temperature. This
causes corn harvested during high temperature con-
ditions to be less sweet than corn harvested in cooler
weather. For highest quality, harvest sweet corn in
the cool of early morning and keep as cool as possible
until sold.
Soils
A deep, sandy loam topsoil well supplied with
organic matter favors rapid growth and development
and maximum yield of early varieties. Loams and clay
loams. are ideal for later varieties which remove more
water and fertilizer from the soil. Sweet corn grows
well from pH 5.5 to 7.0, but for best growth and
fertilizer efficiency, lime highly acid soils to bring
them into the 6.0 to 6.5 pH range. To be effective
lime must be preplant incorporated into the soil 4 to
12 inches.
Texas Agricultural Extension Service. The Texas A&M University System. Daniel C. Pfannstlel, Director. College Station, Texas
Varieties
Restrict large-scale plantings to varieties ofproven
adaptability in a given area. New varieties are best
confined to trial plantings of an acre or less in size.
Successful varieties for Texas include:
Approximate
Variety days to
name maturity Color
Aztec 68 Yellow
Cherokee 79 Yellow
Guardian 79 Yellow
Honeycomb*'" 79 Yellow
Merit 80 Yellow
Calumet 81 Yellow
Bonanza 82 Yellow
Capitan 82 Yellow
Aristogold* 85 Yellow
Silver Queen 92 White
"Far West Texas
""High Plains
Ferti Iization
The amount of fertilizer applied before planting
sweet corn depends on the levels of essential ele-
ments present as indicated by a soil test. Also consid-
er the soil type, previous cropping history, number of
plants per acre, methods of fertilizer application,
rainfall and variety.
Generally sweet corn removes 50 to 60 pounds of
, 15 to 25 pounds of P20 S and 18 to 25 pounds of
K20 per acre. Banding 80 to 120 pounds of ,50 to 60
pounds of P20 S and 40 to 50 pounds of K20 in soils
deficient in potassium, 2 to 3 inches to one side and 1
to 2 inches below the seed at planting time is suffi-
cient under most conditions. A side dressing of 25 to
30 pounds of actual N per acre before tassel elonga-
tion usually is needed to assure adequate N especially
under cool, wet conditions or if the foliage appears
yellow before tasseling. This is especially true for late
varieties grown on sandy soils where nitrogen is
leached easily during periods of high rainfall.
Planting
Sweet corn usually is seeded one row per bed on
40-inch centers. Eight to 15 pounds of seed per acre
are required depending on plant spacing and seed
size. A plant spacing of 6 to 9 inches in the row
generally results in the highest yield of large ears of
early varieties. For maximum ear size on later
varieties which sometimes bear two ears per stalk,
space plants 10 to 12 inches apart in the row. Large
seed produce more vigorous plants, earlier maturity
and greater yield. Do not plant seed deeper than 1V2 to
2 inches. Treat seed to resist damage from seed-corn
maggot and soil fungi.
For direct-to-consumer sales outlets, plant one
variety of sweet corn in small blocks at 10- to 14-day
intervals or plant early, medium and late varieties on
the same day to insure a continuous supply of a
manageable quantity of corn at harvest time.
When planting sweet corn for the pick-your-own
market, divide the field into blocks (figure 1). Plant
the blocks in a staggered pattern so that at harvest
time customers can easily tell which planting is ma-
ture. Plant vacant blocks to other crops before or after
the corn. If chemical weed control is used on the
corn, assure compatibility with other crops to be
planted on the same land.
~
rn
Figure 1. Planting in blocks at 10- to 14-day intervals
spreads maturity and makes supervision ofpick-your-
own customers easier at harvest time.
Irrigation
Early sweet corn varieties require 12 to 16 inches
of water per acre while late varieties may use 20 to 25
inches. Give careful attention to maintaining near
optimum soil moisture for highest yield and quality.
Assure adequate moisture at germination, silking and
during ear enlargement. The water-absorbing roots
are shallow, seldom deeper than 12 to 18 inches. Late
varieties root deeper and require more water less
often to develop larger plants and ears.
Weed Control
The rapid growth of sweet corn accompanied by
one or two timely shallow cultivations may provide
adequate weed control.
When chemical weed control is deemed necessary
effective herbicides are available to control weeds in
sweet corn. Eradicane® at 3 to 4 pounds active ingre-
dient (33/4 to 43/4 pints/acre) applied preplant and
incorporated into the soil provides adequate weed
control. In some cases where heavy populations of
broadleaved weeds are present Atrazine (Aatrex®) or
a combination may be needed. Do not u e Atrazine if
corn is to be followed by a different vegetable the
current season. Follow mixing instructions on the
label to prevent settling out of herbicide. Read and
follow label instructions for specific weeds and grasses
to be controlled and application instructions.
Chemicals which require incorporation must be
mixed thoroughly into the soil for best results. This
requires power-driven cultivation equipment set to
cut to a depth of 2 to 3 inches or tandem disks set to
cut to a depth of 4 to 6 inches. Dry soils and tractor.
speeds of 4 to 6 miles per hour are conducive for best
mixing.
Cultivation
H crusting or surface cracking occurs or weeds
appear, cultivating with sweeps or a LiIIiston rolling
cultivator no deeper than 1 or 2 inches destroys weed
seedlings and restores permeability to the surface
soil. Late cultivation does not increase yield and may
prune roots near the surface.
Diseases
Several sweet corn diseases limit production.
Maize Dwarf Mosaic Virus (MDMV) is a virus disease
that causes leaf mottling and stunting of affected
plants. Severely infected plants fail to form market-
able ears. Under cool weather conditions, diseased
plants may turn red. The virus is transmitted by
aphids from johnsongrass to sweet corn. Downy mil-
dew is a fungus disease that overwinters in the soil
and attacks plants at the seedling stage or later in the
growing season. Affected seedlings have a condition
known as crazy top. Older affected plants do not form
marketable ears. A white, downy-like growth is some-
times visible on the underside of leaves.
Other diseases are bacterial wilt, which is trans-
mitted by insects, corn smut, stalk and root rot,
seedling damping-off, ear rot, rust and numerous leaf
spots. These diseases are controlled with a combina-
tion of practices. Use adapted varieties resistant to
MDMV, downy mildew and bacterial wilt. Crop rota-
tion reduces losses from downy mildew, stalk rot and
other soilborne diseases. Southern corn leaf blight, if
common in the area, can be reduced by periodic
application of foliar fungicides. Rusts, although pre-
sent in most sweet corn plantings, seldom do measur-
able economic damage. Some varieties are resistant to
this disease and should be used where rusts are a
major problem.
Insects
Wireworm, southern corn root worm, seed-corn
maggot, corn leaf aphid, fall armyworm, corn ear-
worm, southwestern corn borer and lessor cornstalk
borer sometimes damage sweet corn. Use seed
treated with an insecticide and fungicide. Where
wireworm or seed-corn maggot are present in damag-
ing numbers, apply granular diazinon broadcast and
disk into the soil before planting. Aphids seldom
reach populations that reduce yield but malathion at
0.93 pounds per acre will effectively reduce large
populations. Control fall armyworm and corn ear-
worm with carbaryl (Sevin®) at 1 to 2 pounds active
chemical per acre. Also use lannate or methyl parath-
ion at labeled rates for certain larval pests. Begin
watching for activity of these insects from the time the
plants are knee high. Chemicals and rates mentioned
are EPA approved at the time of this printing; howev-
er, they are subject to change, so growers should read
and carefully follow pesticide label.
Harvesting and Packing
Most sweet corn varieties are ready for harvest
about 21 days after appearance of the silk.
Sweet corn can be picked with mechanical har-
vesters or by hand. Kernel sugar content is at its
maximum level until the kernel pericarp becomes
rigid. Unharvested sweet corn passes from the pre-
milk or blister stage to over maturity for canning in 11
days at a mean temperature of 75° F., 9 days at 80° F.
and 7 days at 85° F. For direct sales operations
schedule plantings to obtain harvest maturity each 7
days during the season.
Most Texas sweet corn is harvested by hand.
Mechanical harvesters are available if the acreage is
large enough to justify the cost of the machine.
Cool the harvested ears as quickly as possible to
reduce the conversion of sugars to starch. Passing the
ears through 40° F. water from a hydrocooler effec-
tively removes field heat. For long distance shipping
after the ears are cooled, pack in waxed cartons,
wooden crates or mesh bags with 5 dozen ears per
container. Ship topped with ice or in refrigerated
trucks. Hold stored sweet corn at 32° F. and 90
percent relative humidity.
Sweet corn stored at 32° F. for 24 hours loses 8
percent of its sugar, while corn stored at 86° F. for the
same length of time loses 50 percent of its sugar.
When harvesting for direct sales outlets, harvest
only 1 day's supply and keep as cool as possible after
harvest.
Yields from irrigated sweet corn in Texas range
from 150 to 200 bushels per acre.
Marketing
Texas-grown sweet corn is sold on the fresh mar-
ket. Movement by truck to northern and eastern
markets has been common in the past, but in recent
years production and harvesting costs have curtailed
out-of-state shipments. Almost all sweet corn pro-
duced in Texas is consumed in Texas.
Roadside stands or local farmers markets are more
popular for merchandizing sweet corn from small
acreages.
Sweet corn is an excellent crop for roadside stands
and other direct marketing outlets. The quantity de-
manded each day by the marketing outlet varies
considerably with the location and size of the outlet
and buying habits of local customers.
Other publications that may be helpful are availa-
ble from your local county Extension agent.
B-1305 Texas Guide for Controlling Insects on
Commercial Vegetable Crops
MP-902 Texas Guide for Reducing Vegetable Dis-
ease Losses
B-1368 Suggestions for Weed Control with Chem-
icals in Horticultural Crops
ACK OWLEDGME T
The authors acknowledge the assistance of Dr. Charles Cole, Extension entomologist; Dr. Jerral
Johnson, Extension plant pathologist; Dr. W. E. Black, Extension economist-marketing and policy;
and Gordon Powell, Extension economist-fruit and vegetable marketing, The Texas A&M Univer-
sity System.
The information given herein is for educational purposes only. Reference to commercial products or trade names is made with
the understanding that '10 discrimination is intended and no endorsement by the Cooperative Extension Service is implied.
Educational programs conducted by the Texas Agricultural Extension Service serve people ofall ages regardless of socioeconomic level, race,
color, sex, religion or national origin.
Cooperative Extension Work in Agriculture and Home Economics, The Texas A&M University System and the United States Department of
Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8, 1914, as amended, and June 30, 1914.
lOM-6-82, Revision HORT 6-6


Keys to Profitable Sweet Corn Production for Wholesale and Direct Sales Markets.

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Keys to Profitable Sweet Corn Production for Wholesale and Direct Sales Markets.

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