Just How Sweet is That Variety of Sweet Corn?

When you are selecting sweet corn varieties for 1999, look for the abbreviations "su," "se" and "sh2" in the description that follows the variety name. We have seen these abbreviations, but do we know what they mean and what implication they carry?

The first abbreviation, "su," stands for "normal sugary," indicating a variety with this designation produces kernels containing moderate but varying degrees of sugar. The overall sugar content depends on the variety, but in general "su" varieties accumulate two times more sugar than standard field corn.

Sugars in these varieties are converted to starch rapidly following harvest if you fail to refrigerate the sweet corn immediately after harvest. Sweet corn should be refrigerated as soon as possible following harvest in order to maintain sweetness and flavor. Sweet corn can be stored at near freezing temperatures around 40 F - a common setting for most refrigerators.

The second abbreviation, "se" and "se+," stands for "sugary enhanced." Varieties with this designation contain more sugars than "su" types. On average, "se" varieties, if refrigerated, will remain sweeter for two to fours days following harvest. This happens because the conversion of sugar to starch is greatly reduced in "se" varieties compared to "su" types. "Se" types remain sweeter and more tender than their "su" varieties. No isolation is necessary from "su" sweet corn when planting "se" (or se+) sweet corn in the same area. "Se+" sweet corn varieties are even sweeter and more tender that "se" sweet corn.

The third abbreviation, "sh2," stands for "shrunken" owing to the appearance of the kernels of "sh2" sweet corn. These "sh2" varieties are often referred to as "super sweets" because they contain two to three times more sugar than "se" types and the conversion of sugar to starch in these varieties is negligible. If kept refrigerated, these "sh2" varieties remain sweet up to 10 days following harvest.

The most important item to remember when planting super sweets is to isolate them at least 300 feet from "su," "se" and "se+" sweet corn plantings. Otherwise the corn will cross-pollinate and produce starchy kernels. Several "sh2" varieties are stubborn to germinate uniformly. Kernels (seed) of these varieties must absorb twice as much water as "su" and "se" types before they begin to germinate and emerge.

When planting "sh2" sweet corn, water them well and keep the soil moist (but not soaking wet) until you see plants emerge from the soil. Also, be sure soil temperatures are above 70 F . Lower soil temperatures will slow germination and may favor the development of diseases that can cause seed to rot in the ground before they have a chance to germinate.