By ANDREA MCCANN
Indiana Correspondent
(Contribution by Aaron McCann)

VINCENNES, Ind. — Being able to correctly identify wheat growth stages is key to managing the crop, according to specialists who spoke to farmers during a recent workshop at the Southwest Purdue Ag Center.

Chemical applications are more effective and cost-efficient at certain times in the growth cycle, they said, so recognizing growth stages helps producers make timely, profitable management decisions. The Feekes Scale is commonly used in the United States to describe wheat growth stages, according to a Purdue University Cooperative Extension Service publication.

A numerical scale, it ranges from Feekes 1 to Feekes 11.4. Each number represents a stage in the crop’s development. In general, Purdue weed scientist Bill Johnson explained, Feekes 1-2 encompass fall growth; Feekes 3-5 are the dormant winter stages; and Feekes 6-10 include the peak spring growth stages.

Feekes 1 is the emergence stage, according to Managing Wheat by Growth Stage, written by Johnson, Purdue plant pathologist Kiersten Wise, Purdue agronomist Chuck Mansfield, based at Vincennes University, and Christian Krupke, Purdue entomologist. In that stage, farmers should check for uniform emergence and determine if herbicide application is necessary. They should also begin monitoring for aphid infestations.

“Barley yellow dwarf virus is vectored by most aphid species,” Purdue entomologist Larry Bledsoe told producers. He said there’s no rescue treatment for the disease, which causes spot yellowing of the young crop, so prevention is key.

“Plant late in the fall when aphids are dormant, control volunteer plants and treat infestations with a foliar insecticide.”

When wheat plants begin to tiller, or grow side shoots, they’re in the Feekes 2 stage. In Feekes 2, producers can adapt the scale and use a decimal point followed by the number of tillers to assign intermediate growth stages, if they wish.

For example, Feekes 2.4 would designate a plant with four tillers shooting off the main stem. When tillers are through forming, the crop is in Feekes 3.
Early nitrogen should be applied in Feekes 2-3 to enhance tillering in thin stands, according to the publication. Early plantings, and those in mild weather years, may complete tillering in the fall; however, tillering may begin in fall and not be complete until the crop comes out of dormancy in spring.

If nitrogen is applied in fall, 20-30 pounds per acre is sufficient. For spring nitrogen applications, 30-50 pounds is recommended when the crop breaks dormancy. The balance of the spring nitrogen can be topdressed at Feekes 5.
“Nitrogen nutrition is important,” Mansfield said. “It stimulates tiller survival and development.”

After tillers form, the wheat plants begin erect growth and green up. This indicates Feekes 4. It’s difficult to differentiate between Feekes 4 and 5, which quickly follows, according to the specialists. Besides topdressing nitrogen at Feekes 4-5, it’s a good time to apply post-emergence herbicides for weed control and to scout for soilborne viral disease and early-season foliar disease.
“2,4-D is the most common herbicide in Indiana,” Johnson said. “It’s used in the spring before jointing.”

Feekes 5 won’t occur until after vernalization, or winter chill. Any additional tillers that form after Feekes 5 won’t contribute to yield, so at this point the number of spikelets per spike can be determined.

Jointing occurs in Feekes 6, when the first node becomes visible at the base of the shoot. The head will be visible in the stem, and the spike will contain all potential spikelets and florets at this stage. This is the cutoff point for nitrogen and certain herbicide applications to avoid injury to the crop.

When two nodes are visible above the soil line, the plants have reached Feekes 7, a recommended time to scout for insect and disease problems. In Indiana, Bledsoe told the growers, grain aphids, Hessian fly, cereal leaf beetle and armyworm are the primary wheat pests.

Once the flag leaf emerges, the crop has reached Feekes 8, which is a critical stage for management decisions such as herbicide and fungicide application.
“Those who carefully observed growth stages before this point will have an advantage in making decisions to apply fungicides to protect the flag leaf,” the specialists state in Managing Wheat by Growth Stage.

“The flag leaf and next lower leaf are important, after the head develops, for photosynthesis and disease prevention,” Mansfield added, saying if they’re in good shape, grain fill should be good.

Within five days of flag leaf emergence, wheat plants will enter Feekes 9. The flag leaf’s ligule is visible, and the leaf has fully emerged from the whorl. The flag leaf sheath will extend, and the head will begin to swell.

Feekes 10 is when the head develops and is visible in the leaf sheath directly below the flag leaf. This is commonly called the “boot stage.” At this stage, decimals are again used to better describe development.

They can be assigned when 50 percent of the plants have reached the same sub-stage. Breakdowns include: 10.1, awns visible and heads emerging; 10.3, heading half complete; 10.5, heading complete; 10.5.1, flowering begins; 10.5.3, pollination complete; and 10.5.4, ripening begins.

Wise told growers that fungicides can be applied in Feekes 8-10. “Early and split applications don’t normally improve yield,” she said.

University of Illinois crop scientist Carl Bradley said, “Control depends on what crop you follow.”

Following corn exposes the wheat crop to fusarium head blight, or scab, he said, because corn stubble is a source of fusarium spores. Wet weather with high humidity and temperatures of 75-85 Fahrenheit provides favorable conditions for scab to take hold.

Bradley said Caramba and Prosaro are two fungicides that can be applied at Feekes 10.5 to manage the disease. Because the wheat will have headed and the anthers will be showing, applications must be kept below 2 parts per million to avoid dockage at the elevator. Combining use of resistant seed and fungicides provided 90 percent control in field trials, he added.

When ripening begins, at Feekes 10.5.4, the kernels are of a watery consistency. They become milky at Feekes 11.1, doughy or mealy at Feekes 11.2 and hardened by Feekes 11.3. Harvest can occur at Feekes 11.4.

Recommended resources for wheat producers include extension specialists, who can be reached by calling 888-EXT-INFO (398-4636), Purdue extension publications available at www.the-education-store.com and the Purdue field crops IPM site at www.extension.entm.purdue.edu/fieldcropsipm