Sweet Corn ( Zea mays var. rugosa )

1. Sweet Corn (Zea mays var. rugosa) • Key points: • Difference from other corns • 3 categories of sweet corn • Wind pollination and its implications • Succession • Problems

2. Sweet Corn is unlike other corns • _________________ • Produces and retains large amounts of sugar in the kernels, rather than starch • Pericarp • The skin of __________ is thinner, making them tender • Seed is wrinkled when _______________ Sweet corn seed

3. Types of Sweet Corn • ____________ cultivars • Contain the “sugary” gene (su) • Have less initial kernel sugar than other sweet corn types • Sugary enhancer • Contain the “___________________” (se) gene • Significantly raises the sugar content above standard cultivars • Taste, tenderness, and texture are outstanding

4. Types of Sweet Corn • Supersweet cultivars • Contain the “shrunken-2” gene (sh2) • Much initial R & D was done at University of _______ in 1950s • Hold sweetness longer than su or se types • Kernels have a crispy, tough-skinned texture • Require ______________ soils for germination than others • Must be isolated from other types of corn ______ at same time

5. Sweet Corn: Planting • To have sweet corn throughout the summer must have succession plantings • Use both __________________ timing (temporal) and cultivars with different maturity (___________________) • Example of a planting regime • First planting (varietal succession) • _________________ crop cultivar • Main crop cultivar • Second planting (temporal succession) • Same cultivar when three to four leaves have appeared on the seedlings in the previous planting

6. Sweet Corn Reproduction • Flowers • Separate male and female flowers on each plant • Which is which?

7. Sweet Corn Reproduction • Male flowers are tassels • Spikelets contain ____________ , which produce pollen Branch of tassel

8. Sweet Corn Reproduction • Female flowers are ______________ • Each potential kernel produces a silk, on which the pollen lands for fertilization

9. Sweet Corn Development • Plants have a tendency to produce “________________” or “tillers” • Don’t really need to be removed; can’t compete with main stalk

10. Sweet Corn: Pollination • _______________ pollinated • Plant sweet corn in _________ of at least four rows to ensure good pollination • Cross-pollination • Prevent from cross pollination by field corn, __________________ corn, or popcorn • Especially supersweet cultivars because if pollinated by other corns they will not develop high sugar content • Cross pollination between ___________ and white cultivars will affect appearance of white corn

11. Sweet corn – cross pollination • Cross pollination between yellow and white __________ will affect appearance of white corn • Yellow color – most common in midwest • _________ (“butter and sugar”) - common in northeast • White – local popularity • Specialty types – i.e. blue

12. Incomplete pollination • Incomplete __________ development • Lack of tip fill • Blanking • Causes • Not planting enough sweet corn • Lack of moisture • Hot weather • Inadequate fertilizer • Birds • Insect feeding on silks

13. Sweet Corn: Harvesting • Ears should be picked during “_______ phase” • Juice of the kernel appears ______, not thick • Occurs ~20 days after appearance of first silks • Harvest time indicators • Drying and ___________ of the silks • Fullness of the ________ • Firmness of the unhusked ears

14. Sweet Corn: Problems • Corn ______________ • Once caterpillar is ________ husk, there is no effective control • Bt or mineral oil on young silks may help prevent entry • Can insert _____________ gene for Bt protein into sweet corn

15. Sweet Corn: Problems • ___________ beetle • Carry Stewart’s _________ • Yellow streaking of leaves, ___________, plant death • More severe in southern IL

16. Sweet Corn: Problems • Smut • Caused by a ________ that invades kernels or tassels • More severe in hot,_____ conditions and with white cultivars • Culinary delicacy, especially in __________ • Called cuitlacoche • Can cause contractions in pregnant women

17. Sweet Corn: Problems • Raccoons • Raccoons eat sweet corn when it is in the early ____________ phase, just before the ears are ready to harvest • Hard to control • ____________ can be necessary • Watch for tracks