Gdu Update July 31

Current GDU Accumulation from the Pioneer Growing Point Website:

Location in Iowa

2008 GDUs Accumulated 4/20 – 7/31

2009 GDUs Accumulated 4/20 – 7/31

30 Year Average

+/30 Year Average

Algona

1570

1541

1677

-136

Carroll

1854

1739

1867

-128

Fort Dodge

1667

1531

1631

-100

Le Mars

1763

1760

1881

-121

Orange City

1604

1570

1952

-382

Spencer

1563

1476

1698

-222

Spirit Lake

1762

1295

1675

-380

Storm Lake

1792

1660

1717

-57

Sumner

1555

1444

1722

-278

How are GDUs determined? The formula for GDUs is: High temperature + low temperature – 50 = GDUs 2

Guidelines: 1. The high temperature used in the calculation can not exceed 86 degrees 2. The low temperature used in the calculation can not be less than 50 degrees Examples: High Temp 80 90 70

Low Temp 60 60 45

Calculation

GDUs

80+60/2-50 86+60/2-50 70+50/2-50

20 23 10

To find up to date GDU information:    

Navigate to www.pioneer.com/growingpoint Click on the Weather Tab Click on the Weather Tools Menu Select Growing Degree Unit Calculator

Corn Growing Degree Unit Chart The chart below is from the Growing point website and details some of the highlights of corn growth and development based on GDUs. Growth Stage

Aprox. Cum. GDU's GDU's Comments

VE Emergence

100

100

Nodal root system initiated.

V3

3 Leaves

180

280

Growing point below soil.

V6

6 Leaves

180

460

Growing point above soild.

V9

9 Leaves

180

640

Rapid growth phase begins. # of kernel rows established V9V12.

V12 12 Leaves

180

820

Ovule # and ear size being determined now thru V17

V15 15 Leaves

180

1000

V18 18 Leaves

180

1180 Moisture stress can now cause silk delay.

V19 19 Leaves

60

1240

VT Tassel

60

1300 Last tassel branch visible. Cum. # of GDU's Days++

R1 Silking

60

1360 3

R2 Blister

300

1660 12

R3 Milk

200

1860 8

R4 Dough

140

2000 6

R5 Dent

300

2300 13

1/2 Milkline

220

2520 11

R6 Black Layer

200

2720 11