Corn

• Single most important crop in the US• 20% of all crop land is planted in

corn

• Corn belt– Iowa, Illinois, Nebraska, Minnesota,

Indiana, and Ohio

• The corn belt accounts for 80% of all corn grown in the US.

Corn

• Is grown in every state except Alaska.

• Corn was produced as early as 6000 BC

• It can be grown at below sea level to 13,00 feet.

• It is a warm season crop

Uses Feedstuffs

– 12% Silage– 83% Feed, Seed– 5% Mixed Feed

Foodstuffs

• Wet Milled – Starch, Syrups, Oils

• Dry Milled – Meal, Flour, Hominy Grits, Breakfast Cereals, Corn nuts

Types of Corn pg 589• Dent – Silage, Grain• Flint – Hard• Flour – Indian Corn• Pop – Extreme form of flint corn• Sweet – Mutant of dent corn• Waxy – Soft kernel, adhesives,

baby food, puddings, pie filling, tapioca, clam chowder.

• Pod - Primative• Syrup - Karo

Commercial Varieties

• Open-Pollinated –OP’s, save and replant the seed.

• Hybrid – 1877 the 1st. Controlled cross– Can’t replant seed

Degree Days (Heat Units)

• 100-150 to emerge• 1400-1500 to reach Anthesis

(flower)• Another 1200 – 1300 to reach

physiological maturity

Calculating a degree day

• (Max. Temp. + Min. Temp.) - 50 _______________________

                2

50 = base temp for corn

Used to determine planting dates.

Accumulated Relative

GDD (Heat Units) Maturity (Days)

1750-1850 70

1850-1950 75

1950-2050 80

2050-2150 85

2150-2250 90

2250-2350 95

2350-2450 100

2400-2500 105

Growth Stages – Table 21-1

• Vegetative• VE =

emergence• V1 = first leaf• V2 = second

leaf• V3 = third leaf• Vn = nth leaf• VT = tasseling

• Reproductive• R1 = silking• R2 = blister• R3 = milk• R4 - dough• R5 = dent• R6 =

physiological maturity

Seed bed prep• Fine, Firm, Moist

– Disk stubble 1-2x– Chisel– Disk 1x – ring roller– Pre-irrigate– (Fertilize – Dry) – Disk 1-2x– (NH3)– Herbicide, Cross disk, Harrow– Plant

Seed bed – Double crop

• Lime, Gypsum, Potash• Disk 1x• Chisel• Disk 1x• Pre Irrigate w/100# N• Disk – Herbicide• Cross Springtooth• Plant in 24 hours• Ring Roll

Seed bed – single crop

• Fall: – Disk 2x– Chisel 2x– Plane 2x– ListJan: Cultivate – Lilliston or alloway

Spring : Plant

Seeding Rates

• Ranges between 25,000 to 45,000 plants per acre.

• 35,000 is optimum (high plantings are pushing 200 bushels per acre)– Silage is seeded more closely than

this rate.

Crop rotation

• 2 year = corn – small grain

• 3year = corn – small grain – clover rotation

• 4 year = corn – oats – wheat – clover rotation

Fertilization

• Nitrogen 300-325 lbs.

• Phosphate 120 lbs.• Potash 270 lbs.• Sulfur 40-45 lbs.• Magnesium 50 lbs.• Calcium 60 lbs.• Iron 3 lbs.• Manganese 2.5 – 3 lbs.• Zinc .5 lbs.

Irrigation

• 18 – 22” of water.

• Critical periods are early tassel, silking, and blister kernel stages.

• for most corn, that would be 40 – 80 days after emergence.

Weed management

• Roundup Ultra/RT• Lasso• Atrazine • 2,4-D• Basagram• Dual• Prowl

Harvesting

• Kernel Moisture 34%• Grain corn at 20% moisture• Sweet corn = milk stage (21 days

after silking)• Silage corn = when ears are glazed &

most leaves are on the plant, slight dent.

• Fresh Corn at 70% moisture. (can/frozen) – 5-6% sugar & 10 – 11% starch

GradesGrading Factors

#1 #2 #3 #4 #5

Min. lb limits of test weight (lb/bushel)

56.0 54.0 52.0 49.0 46.0

Max. % limits of Damaged kernels

0.1 0.2 0.5 1.0 3.0

Heat Total

3.0 5.0 7.0 10.0 15.0

Broken corn & foreign material

2.0 3.0 4.0 5.0 7.0

Diseases

• Common Rust• Corn Smut• Fusarium Ear Rot• Furarium Stalk Rot

Common Rust• Symptoms• Common rust causes

pustules that may appear on any aboveground part of the corn plant but they are most abundant on leaves. The pustules, which may erupt and become powdery, occur nearly simultaneously on both leaf surfaces. They are golden brown to cinnamon brown, becoming black as the spores mature.

Corn Smut

• Common smut is easily recognized by the tumorlike galls that form on any aboveground plant part. The conspicuous galls that replace kernels are covered with a greenish-white papery tissue.

Fusarium Ear Rot

• white to salmon-pink discoloration of individual kernels or groups of kernels scattered over the ear.

Furarium Stalk Rot

• Corn plants with Fusarium stalk rot exhibit rotting of the roots, plant base, and lower internodes. The rot normally begins soon after pollination.

Insects

• Beet Armyworm• Western Striped Armyworm• Corn Earworm• Cutworm• Grasshopper

Western yellow striped Armyworm

Beet Armyworm

Corn Earworm

Cutworm

Grasshopper