Farm Calls: Sweet Corn Varieties & Postharvest Capability

Recently, a sweet corn grower considering new marketing opportunities asked:

“I don’t farm enough sweet corn acreage to support a hydro cooler or package icing equipment for rapid field heat removal at harvest.
With less than ideal postharvest handling cooling equipment, which varieties should I consider growing if I want to maximize both marketable shelf life and eating quality in order to win repeat sales from direct market and wholesale customers?”

Frosty White (se) Corn.
Photo: Crookham Co. 2011

County Ag Agent Ray Samulis, with 30+ years of expertise in sweet corn, remarks that top eating quality sweet corn has gotten easier to grow but variety selection has become much more complicated.

Color is a factor. NJ regional customers prefer white varieties. Bicolor varieties also attract customer attention to increase novelty impulse purchases. Consider varieties Sensor, Temptation, Obsession or Providence. Fewer NJ customers prefer yellow corn, though there are many good varieties.

Variety Selection Keeping Postharvest Handling in Mind

Sugary enhanced (se) varieties are the most tender and offer their best qualities when produced for local same-day direct retail or wholesale market sales. Homozygous se varieties like Frosty or Whiteout can hold their quality for 2 to 4 days if quickly cooled to remove field heat and held refrigerated.
Supersweet (sh₂) varieties are more forgiving of imperfect or extended postharvest time to consumption. They are sweet and hold well, but do not have the best reputation for tenderness. Recommended white sh₂ varieties include Munition.
Synergistic (sy) and Augmented (Aug) genotype varieties combine sh₂ plus se. They are also very sweet and handling tolerant and can serve sales outlets where corn might sit at retail for a while and not be replaced daily as at farm stands. Varieties include Avalon, Devotion, Mattipoisett, Providence, or Xtra-Tender 372A. They require isolation from older variety types, which may limit production on smaller farms. The Aug Triplesweet™ varieties like Providence bicolor are a bit less demanding of isolation. See page F174 of the 2014 Commercial Vegetable Recommendations for isolation requirements.

Harvest and Postharvest Handling Key Points

Focus on early morning harvesting (before or at sunrise) and same day delivery as key determinants of sweet corn quality.
Sweet corn shelf life and culinary quality are unforgiving of cold chain mishandling. Holding as close as possible to 32°F and 90-95% RH at all times after harvest maximizes marketable shelf life for customers and wins repeat sales. Sweet corn is insensitive to chilling injury.
Package icing, forced air room cooling, or hydro cooling are all acceptable cooling methods. Cool sweet corn before it is loaded for delivery. A used hotel/restaurant commercial ice machine or used walk-in cooler might offer sufficient cooling capacity on a small farm. The cooling capacity of refrigerated truck bodies is designed to maintain temperature during delivery (against road friction and heat load), not to cool produce. Unless the refer body is stationary during cooling, sweet corn will not reach its ideal 32°F, and shelf life quality will be brief. While consumers like shucked corn and openness of tray cello-packs, this packaging makes defects such as slight dry back or tip worm damage more noticeable.