A Comprehensive Guide to CORN MANAGEMENT I N K E N T U C K Y Developed by: University of Kentucky Multidisciplinary Extension Team Written by: Morris Bitzer, Agronomy, Co-Editor James Herbek, Agronomy, Co-Editor Ric Bessin, Entomology J.D. Green, Agronomy Greg Ibendahl, Agricultural Economics James Martin, Agronomy Sam McNeill, Biosystems and Agricultural Engineering Michael Montross, Biosystems and Agricultural Engineering Lloyd Murdock, Agronomy Paul Vincelli, Plant Pathology Ken Wells, Agronomy Partial financial support for some of the research reported in this manual as well as full financial support for the printing provided by the Kentucky Corn Growers Association. Mention or display of a trademark, proprietary product, or firm in text or figures does not constitute an endorsement and does not imply approval to the exclusion of other suitable products or firms. Contents Introduction ................................................................................................... 5 Weed Management ................................................................................... 27 Types of Corn ......................................................................................... 5 Life Cycles of Weeds .......................................................................... 27 Special-Purpose Corn ......................................................................... 6 Weed Scouting .................................................................................... 27 White and Yellow Food Grade Corn .............................................. 6 Weed and Corn Interactions .......................................................... 28 Impact of Tillage ................................................................................. 28 Corn Growth and Development ............................................................ 7 Cultural Practices and Mechanical Controls ........................... 29 Tillage Systems ............................................................................................. 8 Herbicide Use and Timing .............................................................. 29 Soil Compaction ................................................................................... 9 Herbicide Persistence and Carryover ......................................... 30 Summary ............................................................................................... 10 Herbicide Interactions ..................................................................... 31 Herbicide-Resistant Weeds ............................................................ 31 Hybrid Selection ......................................................................................... 11 Herbicide-Tolerant Corn Hybrids ................................................. 32 Yield ......................................................................................................... 11 Other Information.............................................................................. 32 Maturity .................................................................................................. 11 Growing Degree Days (GDD) ......................................................... 12 Disease Management .............................................................................. 33 Corn Seed .............................................................................................. 12 Preplant Decisions That Affect Disease Development ....... 33 Crop Rotation....................................................................................... 33 Impact of Biotechnology ........................................................................ 13 Resistant Hybrids ............................................................................... 33 Planting Practices ...................................................................................... 14 Tillage...................................................................................................... 34 Planting Date ....................................................................................... 14 Other Cultural Practices .................................................................. 34 Planting Depth .................................................................................... 14 Fungicides ............................................................................................. 34 Scouting for Diseases ....................................................................... 34 Cropping Rotation Benefits .................................................................. 16 Mycotoxins ............................................................................................ 34 Fertility Management .............................................................................. 17 Diseases of Corn ................................................................................. 35 Introduction ......................................................................................... 17 Acknowledgment .............................................................................. 41 Soil Sampling ....................................................................................... 17 Insect Pests ................................................................................................... 42 Fertilizer Recommendations ......................................................... 18 Insect Resistance through Biotechnology ............................... 42 Crop Sufficiency.................................................................................. 18 Pest Monitoring Procedures .......................................................... 42 Nutrient Balance ................................................................................. 18 Key Factors ............................................................................................ 42 Maintenance Fertilization............................................................... 18 Major Pests ............................................................................................ 42 Combination of Philosophies........................................................ 18 Summary of Fertilizer Recommendation Philosophies...... 19 Economics for Corn Production .......................................................... 48 Liming ..................................................................................................... 19 Enterprise Budgets ............................................................................ 48 Nitrogen ................................................................................................. 21 Partial Budgets .................................................................................... 49 Nitrogen Fertilizers ............................................................................ 22 Cost Concepts ...................................................................................... 49 Upland Soils Wet from Constant Rains ...................................... 23 Economic Concepts .......................................................................... 50 Lower Soils with Short Periods of Flooding Opportunity Cost ............................................................................... 51 (One to Two Days) .................................................................... 23 Corn Harvesting, Handling, Drying, and Storage ....................... 52 Nitrogen Soil Test ............................................................................... 23 Introduction ......................................................................................... 52 Phosphorus and Potassium ........................................................... 24 Preparing for Harvest ....................................................................... 52 Secondary Nutrients and Micronutrients ................................ 24 Harvest Considerations ................................................................... 52 Other Nutrients ................................................................................... 25 Where Do Combine Losses Occur? ............................................. 53 Row Fertilizers ..................................................................................... 25 How to Measure Combine Losses ............................................... 53 Expected Yield Response to Row Fertilizer ............................. 25 Adjustments to Improve Combine Performance .................. 54 Plant Analysis ....................................................................................... 25 Economic Incentive to Reduce Harvest Losses...................... 54 Sampling................................................................................................ 26 Drying Considerations ..................................................................... 54 Sufficiency Level of Nutrients ....................................................... 26 Storage Considerations ................................................................... 55 Nutrient Content and Removal by Corn ................................... 26 Marketing ...................................................................................................... 59 Pricing Methods ................................................................................. 61 Contract Delivery Periods ............................................................... 62 Timing of Grain Sales .......................................................................