Today's Date: 2017-04-29
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Wheat growth stages on this website are modeled using growing degree days. The formula for wheat growing degree days is:

GDD = 0.5 x (Tmax + Tmin) - 32

where maximum or minimum temperatures are capped at 32 F on the low end, and 70 F or 95 F on the high end before and after the crop has reached the 2nd leaf stage. Growing degree days for the season to date are drawn from high-resolution weather analyses provided by Meridian Environmental Technology, Inc. These analyses combine observations from various surface observation networks and remote sensing platforms (e.g., radar and satellite) to arrive at best-guess estimates of the weather each field has been exposed to.

The growing degree day (GDD) to growth stage mapping used for early maturity wheat on this website is provided by Dr. Charla Hollingsworth of the University of Minnesota Extension Service, and is shown in the following table:

Plant Growth Stage Description Required GDD
Planting to Emergence 80 + 50/in of depth
Emergence 0
First leaf emerged 72
Second leaf emerged, tillering is initiated 215
Third leaf emerged 358
Fourth leaf emerged, tillers visible 501
Fifth leaf emerged, tillering ends 644
Sixth leaf emerged, stem extension begins 715
Seventh leaf emerged, stem extension continues 895
Eighth leaf (flag leaf) emerging, stem extension continues 1,001
Flag leaf emerged, stem extension continues 1,075
Boot swollen, awns within stem at flag leaf height 1359
Awns emerging 1430
Head fully emerged, stem extension continues 1502
Flowering begins, stem extension ends 1590
Flowering complete, kernel development begins 1616
Kernel watery ripe, kernel development continues 1673
Hard dough, kernel development ends 2070

Dr. Jochum Wiersma at the University of Minnesota Croookston has provided adjustments to these GDD requirements for other maturity classes, and has also provided maturity classifications for varieties of spring wheat commonly grown in Minnesota. The adjustments are in the form of a multiplicative factors for the GDD requirements listed in the table above.

Variety Maturity Adjustment Factor
Ingot Early 1.00
Briggs Early 1.00
Oklee Early 1.00
Walworth Early 1.00
Dapps Early 1.00
Oxen Early 1.00
Alsen Medium Early 1.02
Reeder Medium Early 1.02
Knudson Medium Early 1.02
Mercury Medium Early 1.02
Parshall Medium Early 1.02
Russ Medium Early 1.02
Hanna Medium Early 1.02
2375 Medium 1.04
Dandy Medium 1.04
HJ98 Medium 1.04
Ivan Medium 1.04
Lars Medium 1.04
Verde Medium Late 1.06
NorPro Medium Late 1.06
Gunner Medium Late 1.06
Granite Late 1.075
Ivan Late 1.075
Marshall Late 1.075

If you find that a variety of wheat you have in production is not listed in the pull-down variety selection menu, generic maturity-based selections are available.

Growth projections for dates in the future are based upon a combination of observed GDDs for days that have already past and climatological temperatures for days in the future. Errors in the growth model as well as deviations of the weather from climatological normals may cause these projections to be in error. Please use this tool only as a rough guide to growth staging and monitor your own fields for more precise growth stage information during critical growth periods.

References:

Bauer, A. A.B. Frank, and A.L. Black. Estimation of spring wheat leaf growth rates and anthesis from air temperature. Agron. J. 76:829-835.

Haun, J.R. 1973. Visual quantification of wheat development. Agron. J. 65:116-119.

Large, E.C. 1954. Growth stages in cereals. Plant Pathol. 3:128-129.

Nelson, J.E., K.D. Kephart, A. Bauer, and J.F. Connor. 1988. Growth Staging Wheat, Barley, and Wild Oat. American Cyanamid Co., Reprint by NDSU Extension Service.