Wheat and barley crops are susceptible to lodging, the bending over of the stems near the ground level. The incidence of lodging has been greatly reduced by the introduction of short, stiff-straw cultivars of the Green Revolution in the 1960s and 1970s.

Lodging is still a problem particularly with high inputs of nitrogen fertilizer and water. Lodging is undesirable due to uneven maturity of the crop, increased moisture content of the grain, decreased grain quality due to grain shriveling as measured by test weight, and increased harvesting costs.

Plant growth regulators help control lodging in wheat and barley. Herbicides, fungicides, and various cultural practices and environmental conditions can also impact lodging.

Various compounds have been used as plant growth regulators in small grains worldwide. Ethephon (Cerone), chlormequat chloride (Cycocel), mepiquat chloride, and trinexapac-ethyl have been used on wheat and barley to control lodging especially in Europe.

In the U.S., ethephon, marketed as Cerone in wheat and barley, is the only plant growth regulator registered for wheat and barley. Ethephon is marketed as Prep for use in cotton as a growth regulator. Chlormequat chloride and trinexapac-ethyl are only registered for turf and ornamentals in the U.S. and are used to suppress growth. Mepiquat chloride is registered for U.S. use in cotton only as a growth regulator and harvest aid.

The use of plant growth regulators on small grains is uncommon in Arizona. Cerone has been used on wheat and barley in the state, primarily in the Willcox area on up to a third of the small grain crop depending on the year.

Lodging is a problem in the Yuma area, but Cerone is generally not applied since the temperature needs to range from 35 and 90 degrees F. for five days after the application. High temperature often exceeds this range during the appropriate time for application.

Cerone is the only plant growth regulator registered for lodging control in wheat and barley in the U.S. Cerone decomposes in the plant to release ethylene, a naturally-occurring plant growth regulator. Cerone reduces lodging by decreasing plant height by one to six inches and increasing the strength of the straw.

The last two to three internodes are shortened by this chemical, particularly the top internode referred to as the peduncle. Cerone also reduces the tendency of barley heads to “neck” towards the ground and for heads to fall off the plant.

The timing of application of Cerone is important for the chemical to be effective and not cause crop injury. Cerone should be applied from the emergence of the last leaf (flag leaf) to the late boot stage, but before the awns emerge. This window of application will last from five to 14 days depending on the weather.

The heads should never be exposed to spray solutions as might occur in cases where the head splits the boot open or the head has emerged. Rain or overhead irrigation received less than six hours after application will reduce or eliminate the chemical’s efficacy.