Sweet Corn Cornucopia of Leftovers Starting with Sweet Corn When we say corn, what do we really mean? Master Gardener Training Level 2 / Final Week June 25, 2013 Dr. Patti Nagai Horticulture Educator Racine County UW Extension What will we learn today? Selecting sweet corn cultivars for community garden or home use How to grow sweet corn successfully Which cultivars to keep separate How to harvest sweet corn Different types of corn History of corn Fun facts Commonly asked questions Is corn a vegetable? Why is sweet corn sweet and field corn not? Why do they bag the tassels on corn plants? Why do they remove the tassels? Why can t sweet corn be planted near other types of corn? Why missing kernels? Other? Vegetable or Not? we eat it as a vegetable Botanically, a corn kernel is a fruit 1
But corn is marketed as a grain Corn closes up 20 Mike McGinnis 06/19/2013 @ 8:37am DES MOINES, Iowa (Agriculture.com) A forecast that calls for a building heat ridge in the Midwest helped the CME Group corn, soybean, and wheat prices settle sharply higher Wednesday. On the week, the corn and wheat markets are up 4%. Corn is big business US is the largest producer of corn in the world USA 333 million metric tons >10 mt/ha China 163 million metric tons 5.4 mt/ha Brazil 51 million metric tons 3.7 mt/ha Mexico20 million metric tons 2.8 mt/ha India 17 million metric tons 2 mt/ha 90,000,000 Acres Planted in US Illinois Iowa Indiana Minnesota South Dakota North Dakota Nebraska Kentucky Ohio Kansas Missouri Corn Belt Heartland Iowa and Illinois grow 1/3 of all corn in the US What is all this corn used for? 38% animal feed 29% ethanol (distillers grains used for animal feed) 8% exported (Japan, Mexico, South Korea, Taiwan, Egypt) 12% food, seed and industrial uses (>3500 uses) ~5% surplus carried over for the next year Food Not Food; Corn is in Everything! Cereal Corn starch Corn oil Sweeteners Popcorn Soda Baby food Ice cream Spaghetti sauce Bologna Wine Peanut butter Ethanol Aspirin Envelopes Toothpaste Fireworks Chalk Crayons Plastics Biodegradeable packing peanuts Disposable cups and to go boxes Corn is an Old Crop One of the oldest cultivated crops Beadle at Cornell, 1930 Research suggested Teosinte as ancient ancestor Not proven definitively until 2009 by team of scientists at multiple universities, including UW 2
Location of Maize finding in Central Balsas located near the Iguala Valley in Guerrero state Over 9000 years old Ranere A J et al. PNAS 2009;106:5014-5018 Types of CORN Zea mays Dent Corn Flint Corn Indian corn Popcorn Flour corn Gourdseed Sweet Corn Shoepeg 2009 by National Academy of Sciences Sweet Corn s Place in the Market Field Corn ~ 90,000,000 acres Sweet Corn ~380,000 acres Popcorn ~201,000 acres 0.2% of corn grown in the US is popcorn 0.4% of corn grown in the US is sweet corn 99% of corn grown in the US in field corn Sweet Corn in Wisconsin Fresh Market ~ $16 million Processing ~ $62 million (2009, USDA) Sweet corn consumption per person annually 8.8 pounds frozen 7.6 pounds canned 9.1 pounds fresh When things go wrong Surprise! Insects like Sweet Corn, too! Pollination? Fertilization of ovules? Soil moisture? Temperature? Insects? Things to consider: Planting only early maturing cultivars IPM techiniques scouting Oil application to silk PyGanic Zea Later Pyrethrum control products (works for beetles also) 3
Pollination by wind Problems with Pollination Female ear + Fruit kernels Male tassel = Asynchronous development Pollen release Silk emergence Insects Corn ear worm Japanese beetle Drought stress Corn Pollen 4 to 5 million pollen grains Corn pollen is large, and heavy Pollen sheds ~5 to 6 days ~2 weeks to complete pollen shedding in an entire field Viable only 1 to 2 hours in the field 97% of kernels on an ear are pollinated from a different plant Corn Silk Each ovule has its own silk Silks mature acropetally (base up) Long, sticky stigma Elongates ~10 days Stops when pollinated Only one pollen grain is needed Many may land and germinate Fertilized ovule develops into the kernel ~1000 ovules/1000 silks on a single ear of sweet corn Detasseling Corn Bagging Tassels and/or Ears Controlled pollination Hybrid seed production Pollinator plants nearby Controlled pollination F1 Hybrids Protection of OP cultivars from stray pollen Inbred Line 1 x Inbred Line 2 = F1 Hybrid 4
Genetic Types of Sweet Corn Normal Sugary (su) Standard sweet corn, Pick and eat same day Isolate from field corn, popcorn and sweet corn except se Sugary Enhanced (se or SE/se) Most tender, longer lasting sweetness than su types Isolate from field corn, popcorn and also sh corn Super Sweets or Extra Sweets (sh2 and sha) Extra wrinkled, do not like cool soil, sweetest of all with longest shelf life after harvest Must be isolated from all other types of corn Synergistic Hybrids (sy; se/sh2) Do not like cool soil, tender kernel, very sweet, hold longer than se Must be isolated from all sh2 types Sweet Corn Cultivars Open Pollinated for Seed Savers Stowell s Evergreen 1848 80 100 days Country Gentleman 1891, 90 93 days Golden Bantam 1902, 78 85 days Hopi Blue 100 days Texas Honey June 97 days Painted Hill 75 days Chires Baby Sweet Corn 75 Ashworth 69 days Hooker s Sweet Indian 75 Aunt Mary s 69 days Cultivars of Normal Sugary Hybrid Sweet Corn (su) Honey & Cream Bicolor, 80 days Earlivee Yellow, 60 days Early Sunglow Yellow, 64 days Sugar Dots Yellow, 85 95 days Silver Queen White, 85 90 days Cultivars of Sugary Enhanced Hybrid Sweet Corn (se and SE/se) Bodacious Yellow, 80 90 days Ambrosia Bicolor, 75 days Sugar Buns Yellow, 70 80 days Precocious (cool soil tol.) Yellow, 65 75 days Kandy Korn (red stalks) Creamy yellow, 89 days Native Gem (cool soil tol.) Bicolor, 67 days Spring Treat Yellow, 68 days Cultivars of Shrunken & Augmented Hybrid Sweet Corn (sh2 and sha) Mr. Mini Mirai Yellow, 74 days How Sweet It Is AAS winner White, 87 days Supersweet Jubilee Yellow, 85 days Espresso (cool soil) Bicolor, 70 days Strong Start 7112 (cool soil) Bicolor, 71 days Cultivating Sweet Corn Warm season Soil temperature ideally above 60F Full sun Nutrient rich soil High N requirement preplant Sidedress with N when 12 inches tall http://www.caes.uga.edu/publications/pubdetail.cfm?pk_id=7638 5
Planting Recommendations 1 ounce of seed will sow about 30 to 45 feet Plant 1 to 1.5 inches deep Space seeds 8 to 12 inches Space rows 24 to 30 inches At least 4 rows! Square is better! Separation of Corn Cultivars Isolate from field corn, popcorn, flint corn: Normal sugary su Sugary Enhanced se Super Sweet sh Isolate from All Corn: Super Sweet sh Separation of Corn Cultivars By Space: 660 feet for seed saving 250 feet recommended 25 60 ft minimally By Time: Sow at least 10 days apart Sow early (60 70 days) and late (85 95 days) maturing cultivars Harvesting Sweet Corn Pay attention to time of silk emergence Silk drying Silk browning Kernels Milky Pick early in day Chill Cook and eat 6