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Chapter 26: Sweet Corn

26.1 Recommended Varieties

Processing
Plant varieties recommended by processors.

Fresh-market
Listed in approximate order of maturity within each class.

Variety DTH4 Type2 Color3 Pest Tolerance1
SW R LB S
Early
Jester II 65 se BC - - - -
Sweet Chorus 67 se BC - - - -
Second Early
Trininty 69 se BC M L M -
Chippawa 71 se BC - - - -
Temptation 72 se BC M M M -
Bon Appetit 73 se BC - - - -
Midseason
Sweet Rhythm 73 sb BC M L L M
Mystique 75 se BC - - - -
Candy Corner 76 sh BC M H - M
Main and Late
Xtra Tender 277 (tr) 77 sh BC H M M H
Bojangles 78 se BC - - - -
Xtra Tender 278 78 sh BC M - M -
Absolute 78 se BC M - M -
Accord 78 se BC M - - -
Obsession 79 sh BC - M M -
Delectable 80 se BC H H H -
Precious Gem 80 se BC M M H -
Bandit 80 sh Y M H M -
Silverado 80 se W H M M H
Zenith 81 sh Y H M M M
Lancelot 82 se BC H H M H
Silver King 82 se W M M M -
Brocade 82 se BC - - - -
Argent 86 se W H M H -
1: Low, medium, and high tolerance ratings provided for Stewart’s bacterial wilt (SW), common rust (R), northern corn leaf blight (LB), and common smut (S).
2: se = sugary enhanced; sb = sweet breed; sh = supersweet; su = sugary
3: BC = bicolor; W = white; Y = yellow
4: DTH = Days to harvest, as suggested by seed companies.

Sweet corn varieties are categorized by their genotype. The most common varieties are normal or sugary (su), sugar enhanced (se), and supersweet or shrunken types (sh2). Other varieties include sweet breeds, synergistic or sweet genes, and improved supersweets. Su types have a short shelf life with sugars rapidly converted to starch soon after picking. Se varieties have a higher initial sugar content which can potentially extend storage life three to five days. Se varieties are either homozygous or heterozygous. Homozygous se corn has two doses of genes and will be sweeter than heterozygous se corn with a single dose of genes. Sh2 varieties are genetically distinct from the su and se varieties. The sugar content of supersweets is twice that of standard sweet corn, and the storage life is extended five to ten days. Not only are supersweets much sweeter, but the texture is distinct from the other two types. Supersweet varieties are also more difficult to establish than se and su types. They germinate poorly at temperatures below 60°F and are easily damaged by rough handling.

Warning. Sh2 varieties need to be isolated by at least 250 feet or 12 days in silking from su and se types or cross pollination will result in a starchy, inedible kernel. Su and se varieties can be planted side by side without this occurring. Be aware that even among corn of the same genotype, pollen from a bicolor or yellow variety on the silk of a white variety will result in an ear with bicolor characteristics. Two to five border rows will protect against this type of cross pollination.

26.2 Planting Methods

Plastic mulches. Clear, perforated, plastic mulch will speed the maturity of early plantings. Seed two weeks earlier than usual in double rows spaced 14 to 16 inches apart on five to six foot centers. Apply herbicide and cover with clear plastic mulch (1 to 1-1/14 mil) four feet wide. Keep plastic over plants for approximately 30 days or until daytime temperatures consistently exceed 75°F. At that time, cut plastic and remove it from the field, usually when plants are six to 12 inches tall.

Another approach is to apply a spun fiber (floating) row cover after planting. Although soil temperatures are not increased as quickly as with plastic, there are advantages. These include use of standard row spacing, less danger of plant injury due to high temperatures, ease of application, and the ability to reuse row covers for several seasons.

Table 26.2.1 Recommended spacing

Row (inch) In-row1 (inch)
30-36 8-12
1: Closer in-row spacing may be used in early plantings while wider in-row spacing is used for late plantings.

26.3 Fertility

Use lime to maintain a pH of 6.0 to 6.2. If soil magnesium is below 100 pounds per acre, use high magnesium lime to adjust pH. For long-term benefit, if soil test zinc is between 1/2 and one pound per acre, broadcast 1/2 pound zinc per acre. If soil zinc is below 1/2 pound per acre, apply one pound zinc per acre. When zinc levels are marginal, an application of one pound of zinc in the fertilizer band may be helpful.

Appropriate nitrogen rates for corn vary greatly among locations and growing seasons.  In some years corn is nitrogen deficient, while in others the same amount of fertilizer appears to be adequate.  This happens because the appropriate N fertilizer rate is highly influenced by weather, soil, and management factors. Notably, early season precipitation has been shown to significantly affect corn fertilizer response.  Much of the plant-available N is lost in years with wet springs, which then require more supplemental nitrogen fertilizer; lower fertilizer rates are needed in dryer years.  Soil type differences and management practices interact with weather and also affect the optimum N rate.

Adapt-N is a computational tool that incorporates the complex interactions among these factors to provide a sound N rate recommendation. It can be accessed from any computer or mobile device with Web access.  Adapt-N  simulates the important processes day by day, incorporating high-resolution (3 x 3 mile) information on precipitation and temperatures, as well as soil type, organic matter content, previous crops, organic inputs (manure, etc.), tillage, planting date and population, cultivars, and yield potential. It can therefore provide a locally and seasonally adaptive N recommendation. At the same time, N losses - and therefore pollution of water and greenhouse gas emissions - are minimized.   For more information and sign-up instructions visit Adapt-N.

Growers may also use the Pre-sidedress Soil Nitrogen Test (PSNT) to determine the need for sidedress nitrogen. The PSNT determines the nitrogen available from manures, cover crops, and previous crops. Contact your County Extension Agent for more details. See Table 26.3.1 for the recommended rates of nitrogen, phosphorus, and potassium.

Table 26.3.1 Recommended nutrients based on soil tests

N pounds/acre P2O5 pounds/acre   K2O pounds/acre Comments
  Soil Phosphorus Level   Soil Potassium Level  
  low med. high   low med. high  
120-140 120 80 40   120 80 40 Total recommended.
40 80 40 0   80 40 0 Broadcast and disk-in.
40 40 40 40   40 40 40 Band place with planter.
40-60 0 0 0   0 0 0 Sidedress when corn is 6" to 12" high.1
1: A second sidedressing could replace the preplant, broadcast application of nitrogen if applied before corn is 12" tall. This is preferable on leachable soils.

26.4 Harvesting

Under normal temperatures, most varieties reach maturity 18 to 21 days after silking. Supersweets have a wider "harvest window" than su and se varieties. Maximum quality is attained when corn is picked at peak maturity and rapidly cooled by hydrocooling or vacuum cooling followed by top or body icing if corn is to be shipped. Corn should be stored at 32° to 40°F and 98 percent relative humidity.

26.5 Disease Management

26.5.1 Anthracnose
26.5.2 Maize Dwarf Mosaic Virus
26.5.3 Barley Yellow Dwarf Luteovirus and Cereal Yellow Dwarf Polerovirus
26.5.4 Northern Corn Leaf Blight
26.5.5 Common Rust
26.5.6 Seed Rots
26.5.7 Common Smuts
26.5.8 Stewart’s Wilt

 

26.6 Insect Management

26.6.1 Corn Flea Beetle
26.6.2 Japanese Beetle
26.6.3 Seedcorn Maggot
26.6.4 Cutworms
26.6.5 Corn Leaf Aphid
26.6.6 Sap Beetle
26.6.7 Western Corn Rootworm
26.6.8 European Corn Borer
26.6.9 Corn Earworm
26.6.10 Fall Armyworm

26.6.11 Western Bean Cutworm

 

26.7 Weed Management

 

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Maintained by Abby Seaman, New York State IPM Program. Last modified 2019.