FARMER'S BOOKSHELF MAIN PAGE
TOPICS:
BACK TO VEGETABLES
FARMER'S BOOKSHELF MAIN PAGE
Adapted Varieties
All available from CTAHR Seed Program, Sherman 108, 1910 Easst-West Road, Honolulu, HI 96822.
Soil Preparation
Sweet corn grows well on a wide variety of soils but medium loams which are well drained and contains a high level of organic matter are preferred. When grown on soils less than a pH of 5.5, yields are likely to be reduced.
Irrigation
Sweet corn has a relatively shallow root system, regular irrigation should be practiced particularly when crop is in an actively growing condition and if rainfall is insufficient to prevent water stress in the plants. It is also important that plants are not water stressed when silks are being formed during early ear development. Adequate irrigation is related to length, weight and diameter of the ears and the number of marketable ears likely to be produced.
Optimum pH= 5.5 - 6.8
Amount of N, P, K Taken Up by Average Crop (lbs./acre)
| N - 155 lbs | P - 20 lbs | K - 105 lbs |
|---|
Soil Amendment and Fertilization
Take a soil test, for most local soils with pH below 5.5 and a calcium content below 2,000 lbs./acre, apply one ton (2,000 lbs.) per acre (4.5 lbs./100 square feet) of agricultural lime or its equivalent 8 - 12 weeks before planting and broadcast incorpor ate at least 8 - 10 inches.
For soils with less than 25 lbs./acre available phosphate, apply 1,000 lbs./acre (2.25 lbs./100 square feet) of treble superphosphate or its equivalent and incorporate at least 8 - 10 inches. Both lime and the phosphate could be incorporated together.
After adjusting deficiencies for pH and phosphorus or for soils within the acceptable pH range and moderate levels of available phosphorus, potassium, magnesium and calcium, incorporate in the planting row before planting or band two inches to the side an d two inches below the planted seed 1,000 lbs. (2.25 lbs./100 square feet) of 10-30-10, 10-20-20 fertilizer or its equivalent at planting.
At about three and six weeks, side dress with about 100 lbs./acre (1/4 lb./100 square feet) urea (46-0-0) plus 500 lbs./acre (1 lb./100 square feet) of 10-20-20 or similar fertilizer and sprinkle irrigate or "hill" to cover fertilizer.
As a general rule, sweet corn response to the addition of micronutrients to the soil is low for boron and molybdenum; medium for manganese, copper and iron; and high for additions of zinc. Zinc deficiency occurs quite commonly on corn here. To correct z inc deficiency, apply zinc sulfate (22.7% Zn) at the rate of 10-40 lbs./acre (2-4 lbs./100 gallons water per acre as foliar spray); or zinc chelate (14% Zn) at 15-40 lbs./acre (3/4-1 lb./100 gallons water per acre as foliar spray) as needed.
Sweet corn is one of the most perishable commodity, a big reason for corn not tasting sweet is because the sugars in the kernel have turned to starch. This conversion takes place rapidly once the ears are picked if they are not refrigerated. A differenc e of two hours from harvest to refrigeration will greatly lower the quality of corn. The temperature of the harvested ear should be reduced to 32 degrees F as quickly as possible. This is usually done by hydrocooling.
It is recommended that sweet corn be stored at 32 degrees F with a relative humidity between 90 - 95%. Storage life under these conditions range between 4 - 8 days.
This varies according to the varieties cultivated, time of year and location; however, for the suggested varieties available locally, 75 days is an average. Generally, it would take about four days longer during winter and about four days less during sum mer.
Estimated Yield= 5,000 lbs./acre; 20 lbs./100 feet row
Harvesting
Approximately 21 days after the silks have appeared, the ears are ready for harvest, given no unusual weather conditions. Ears should be harvested at the proper stage of maturity for their best eating quality. To determine the proper stage at which to h arvest the ear, by feeling or looking at the ears, is a difficult for the uninitiated, however. Here's how: peel the husk off the tops of a few ears and press the kernels with the thumbnail. If the kernels burst open with force, it is in the right stag e for harvest (called the milky stage). Overmature kernels will not burst open. Another test for the right stage is to feel the tightness of the ear tips and the condition of the dried silk.
Modern harvesting machines cut rather than snap the ears to avoid bruising the kernels. These harvesters are equipped to harvest at night when the field heat of the corn is at its lowest level. For specific requirements on grading, consult the Hawaii Gr ading Standard by the State Department of Agriculture.
Propagation
Direct Seeded
Planting Schedule in Hawaii:
Year round from sea level to 3,000 feet elevations.
Spacing
30" to 45" between rows; 8" to 12" between plants.
Amount of Seed
Supersweet Type - 12-15 lbs. per acre, 1/4 lb./100 foot row
H-68 Type - 15-18 lbs. per acre, 1/4 lb./100 foot row
Seeding Depth
3/4" - 1"
Planting
In very windy areas, small plantings of sweet corn should be planted in the form of a square, or, if this is impractical, the rows should start or end facing the direction of the prevailing wind. Since corn is wind pollinated and if the wind blows most o f the pollen off the tassel and away from the silk of the ears, the kernels will be sparsely developed or developed only in spots.
Another important consideration in planting sweet corn is to know the hybrid or variety. Cross-pollination may result in an inferior ear of corn. It is not recommended that any supersweet types be planted next to the Hawaiian Supersweet types. Also, H- 68 should not be planted next to supersweets, etc. Consult your seed catalogues or seed company for interplanting specific hybrids and varieties. Alternatives are: wait about 7 - 10 days between planting or if field space is available, separate the you nger planting approximately 150 - 200 yards to the windward side of the older planting.
