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Reducing Lodging in Small Grains with Growth Regulators (05/26/16)

Weather and crop conditions in the 2015 cropping season resulted in widespread problems with lodging in wheat, barley, and oats.

Reducing Lodging in Small Grains with Growth Regulators

Weather and crop conditions in the 2015 cropping season resulted in widespread problems with lodging in wheat, barley, and oats. The timing of the weather events (heavy thunderstorms and straight line winds) made not only for a cumbersome harvest but also reduced grain yield.

The rule of thumb is that it is ‘three strikes and out’ when it comes to lodging. After both the first and second time that plants lodge, the cells in nodes of lodged stems will stretch on the shaded side of the stem in an attempt to raise the stem upright. The crop can only do that approximately two times before it is unable to straighten itself up.

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To avoid lodging you have several options. First, you can choose varieties with stiffer straw that are less prone to lodging. Secondly, you can reduce your plant population a bit as that also reduces the risk of lodging. A third option that has not been widely adopted in this region is the use of plant growth regulators (PGR’s). PGR’s are synthetic compounds that either mimic plant hormones or interrupt biosynthesis of plant hormones thereby altering the growth and development of the plant. PGR’s are widely used in high yielding environments in Europe (winter wheat) and Chile (spring wheat) to reduce overall plant height, thereby making the plant less prone to lodging. PGR’s do not increase yield potential in wheat, barley, or oats but rather allows yield potential to be maintained by reducing the risk of lodging.

While several of the crop protection companies market a number of PGR’s in the cereal markets in Europe and elsewhere, only Bayer CropScience and Syngenta have products labeled for use in the US cereal market. Bayer CropScience markets Cerone™ while Syngenta markets a product called Pallisade EC™.

Cerone is an older compound that a few may remember from the eighties. Cerone is a bit temperamental in its use as it can delay maturity and is currently labeled for use only east of the Mississippi. The active ingredient in Pallisade is trinexapac-ethyl, and in the US it is labeled for use in wheat, barley, oats, triticale, and rye. This active ingredient inhibits the gibberellin biosynthesis. Gibberellin is a plant hormone that influences, amongst other things, stem elongation. Research in HRSW has demonstrated that trinexapac-ethyl has good crop safety, a relative wide window of application, and it reduces plant height and lodging. The improvement in lodging scores are about 1 to 2 points on the 1 to 9 scale commonly used by breeders. The reductions in lodging scores was the same for all varieties tested, regardless of the initial lodging score assigned to the variety.

Should you consider the use of a PGR in HRSW? The decision tree below is a first attempt to guide that decision.

Question 1:      Was planting delayed past the optimum planting window?

Yes -    You likely will not benefit from the use of a PGR as delayed planting will generally reduce overall plant height and yield potential.

No -     Please go to question 2.

Question 2:      Have the weather/growing conditions been favorable for small grains up to this point? (i.e. cooler than normal conditions with sufficient soil moisture to allow for a lush growth)

No -     You likely will not benefit from the use of a PGR to reduce lodging as your yield potential is likely lower.

Yes -    Please go to question 3

Question 3:      Are you growing a variety that has an average lodging score of 4 or higher?

No-      You likely will not benefit from the use of a PGR to reduce lodging as you are already growing a variety unlikely to lodge.

Yes-     Please go to question 4.

Question 4:      At what growth stage is your crop?

  • Feekes 4 (Leaf sheaths beginning to lengthen but prior to the first node becoming visible):     You may want to consider using a lower dose of Palisade EC and reevaluate crop conditions at Feekes 7 (when the second node becomes visible).
  • Feekes 7:  Consider using the higher labeled rate of Palisade EC to reduce the risk of lodging, especially if the long-term weather forecast is predicted to be favorable for small grain growth and development (i.e. cooler than normal temperatures and adequate rainfall).

                               Always follow label directions

 

Jochum Wiersma

Extension Agronomist

University of Minnesota

 &

Grant Mehring

Research Specialist

 &

Joel Ransom

Extension Agronomist for Cereal Crops

 

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