Journal of the NACAA
ISSN 2158-9429
Volume 14, Issue 1 - June, 2021

SY Wolf Winter Wheat Responses to RyzUp SmartGrass® Application at Third Leaf Stage in East Central Nebraska

Rethwisch, M. D., Farm Advisor - Crop Production and Entomology, University Of California Cooperative Extension - Riverside County
Peterson, T. E., Grower-Producer, Tom Peterson Farms



RyzUp SmartGrass® was applied in early March to winter wheat utilizing large replicated strip trials in eastern Nebraska over a two year period. First year application was with a non-ionic surfactant containing ammonium sulfate, but with foliar fertilizer in year 2. Data were collected on initial foliar growth, grain yield, moisture and seed weight. RyzUp SmartGrass® application resulted in significant plant growth increases which were evident for three weeks post treatment in year 1, and a significant grain yield increase (3.3 bushels/acre). While yield increase in year 2 (3.5 bushels/acre) was not statistically significant, the consistent increase noted across both years was significant (p = 0.019).  


RyzUp SmartGrass® 40WSG (active ingredient = gibberellic acid3, Valent BioSciences LLC) is registered for many grass-type crops, including wheat (Triticum aestivum). When used on winter wheat during tillering but before stem elongation to promote growth, RyzUp SmartGrass® promotional materials note that usage enhances yield potential in winter and spring wheat, increases vigor and plant health on fields suffering from weak stands, and overcomes slow growth due to cold temperatures, winter injury and post emergence herbicides. Gibberellic acid causes cells and subsequently leaves and stems to elongate, thus resulting in increased forage availability for many cool season grasses.  

Usage of this product has been shown to increase numbers of Kentucky bluegrass (Poa pratensis) seed heads when applied early in the season (Rethwisch, unpublished). Smooth brome (Bromus inermis) stem numbers/area were also increased when RyzUp SmartGrass® was applied when plants were just coming out of winter dormancy and beginning to green in a well fertilized environment in one study (Rethwisch et al., 2014).

Increased stem numbers were not found in other experiments when RyzUp SmartGrass® applications were initiated later in smooth brome growth cycle, indicating that plant growth stage is critical for increased seed head/stem production of perennial crops.

While increasing early season forage production is important for wheat producers who also graze wheat prior to seed head formation, many producers grow wheat only for seed/grain production. The effect(s) of RyzUp SmartGrass® on Nebraska wheat production have not been robustly evaluated and documented.

Very little winter wheat growth (var. = WB-Cedar) response was noted following RyzUp SmartGrass® 40WSG application to wheat shortly after green-up in a 2014 University of Nebraska-Lincoln Butler County Extension small plot experiment (Rethwisch & Hruska, 2016). The lack of response was thought primarily due to surfactant used (BioLink Spreader-Sticker). Spring 2014 experiments on smooth brome evaluating various surfactants with RyzUp SmartGrass® noted highly visible and large growth differences, with best results obtained from non-ionic surfactants that also contained ammonium sulfate (Rethwisch et al., 2017). Usage of BioLink® Spreader-Sticker with RyzUp SmartGrass® did not result in the highly visible and large smooth brome growth increases initially noted from other surfactant products however (Rethwisch & Hruska, 2016). Plant size/stage at time of application may also be a factor. 

Limited yield data for wheat yield responses to RyzUp SmartGrass® applications exist from other land grant university trials. North Carolina State University reported an average yield reduction of 1.2 bushels/acre using RyzUp SmartGrass® 40WSG at 0.5 oz./acre and an unidentified non-ionic surfactant when applied at green-up across four locations (Weisz, 2014). 

A 2014 Ohio State University trial evaluated the addition of 0.4 oz./acre of RyzUp SmartGrass to a 17 gallons/acre of urea ammonium nitrogen and 0.14 gallons/acre Agrotain®. Plant growth stage on the March 24 application date was not noted.  This report contained conflicting results, as inclusion of RyzUp SmartGrass® was noted in the table to increase yields by 5.0 bushels/acre, although the narrative indicated the opposite effect (Bruynis, 2014), with the latter being confirmed as correct (Bruynis, per. conversation).  The RyzUp SmartGrass® treated wheat, because it was faster growing and larger, was thought to be more damaged by a late freeze at this site. Yield differences were not statistically different in this experiment.

A 2019 Washington State University experiment noted a non-statistical 9 bushel/acre increase (31 vs. 22) when 0.5 oz./acre of RyzUp SmartGrass® was applied (no surfactant listed) at the three (3) leaf stage (April 9) as a herbicide study component. Yields may have been affected by weed competition, as weed biomass in untreated wheat was almost 2.5x that of RyzUp SmartGrass® treated wheat at harvest (Zuger et al., 2020).   

These experiments were initiated to determine winter wheat growth and yield responses to RyzUp SmartGrass® application under eastern Nebraska production conditions.


Methods and Materials

Fields of SY Wolf hard red winter wheat located northwest of Waverly, Nebraska, were chosen for these experiments during 2016-2017. SY Wolf is a semi-dwarf variety developed by AgriPro/Syngenta, with excellent straw strength, medium maturity, and has very good winter hardiness, moderate resistance to stripe rust, and good resistance to Septoria, tan spot, and powdery mildew. The soil type in fields was Sharpsburg silty clay loam.  Soil sample results from fields when treatments were applied are shown in Table 1.


Table 1. Soil fertility levels from early season 2016 and 2017 soil samples, Waverly, Nebraska.

       Parts per million (ppm)    

Lbs/acre N03

0-8 "

P K Ca Mg Na Sulfate Zn Fe Mn Cu



Soil pH
2016 69 123 471 2,404 348 13 19 1.47 58.6 12.1 1.00 3.8 6.3
2017 47  63 348 2,024 230 38 11 1.37 79.3 18.9 0.75 4.0 6.2

Soil analyzes by Ward Laboratories, 4007 Cherry Avenue. Kearney, NE  68848


RyzUp SmartGrass® treatments were applied in March of both 2016 and 2017 when plants were approximately 3.4 inches tall. Plant growth was somewhat variable across the field in 2016 due to tillage prior to planting. Smallest plant had three (3) collared leaves, while the largest had extended leaf height of 5.0 inches when treated on March 8. Plants averaged 3.4 inches tall (range of 1.5-5.0) with an average canopy width of 3.1 inches (range of 2.0-4.0) when treated (Figure 1).

Figure 1.  Wheat development and size on March 8, 2016.



For the March 20, 2017 application, plant heights and development were very similar to that of 2016, with averages noted of 3.375 inches for plant height, 5.22" extended leaf height, 2.86 collared leaves, and a canopy width of 3.5 inches.  

Applications of RyzUp SmartGrass® differed slightly between 2016 and 2017. In 2016 RyzUp SmartGrass® was applied at 0.5 oz./acre, with AgriSolutionsTM Class Act® NG® (distributed by Winfield Solutions, LLC, St. Paul, MN), a water conditioning agent/non-ionic surfactant blend product, used at 1.9% v/v. Usage of this surfactant with RyzUp SmartGrass® had previously resulted in very consistent results for smooth brome forage production increases (Rethwisch et al., 2017).                    

Class Act® NG® consists of 50.5% ammonium sulfate, corn syrup and alkyl polyglycoside, and 49.5% constituents ineffective as spray adjuvants. This formulation contains 1.3 lbs. of sugar and 3.4 lbs. of dry ammonium sulfate/gallon. At 1.9% v/v Class Act® NG®, this resulted in 0.285 gallons of ClassAct® NG® applied/acre, the equivalent of 0.97 lbs./acre of ammonium sulfate.

Treatments were applied in 15 gallons/acre (gpa) of solution with an Apache AS720 sprayer equipped with AIXR 110025 nozzles 15" apart. Plots were 60 foot wide, and approximately 1,662 ft. long. The treatment was replicated four (4) times in this experiment, alternating with untreated strips on which the sprayer did not traverse.   

In 2017, treatments were applied with the same sprayer as in 2016.  The 2017 base (control) was a 22 gpa fertilizer solution that consisted of 19 gpa of 32-0-0, and 3 gpa of thiosulfate.  After plots were treated with this solution, RyzUp SmartGrass® was added and applied at the rate of 0.46 oz./acre, with no surfactant added. Plots were 1,300 foot long x 60 foot wide.  A randomized complete block design with 5 replications was utilized.  

Plots were sampled in 2016 on March 22 and 29 for natural heights and plant widths. Ten samples were obtained from each plot. Height samples were obtained by placing a ruler in the wheat row, and noting the last height that was no longer obscured by wheat foliage. 

Canopy width samples on March 22 used the outer leaf tips, the same method used to establish plant size on application date. This method was noted to have high levels of variation in sample data on March 22.  Plant growth by March 29 allowed sampling to record width across foliage through which the ruler was no longer visible (narrower than leaf tips). As readily visible differences were not noted in 2017, plant measurements were not obtained. 

Plots were harvested on June 28, 2016, and July 6, 2017, with a John Deere 9670 STS combine with 625F HydroFlex 25 foot wide head. Two 25 ft. individual swaths/plot with no overlap were harvested, and transferred to a Kinze 640 weigh wagon equipped with a DigiStar E2150 electronic scale which measured in 20 lb. increments from which weights/recorded. 

Small sub-samples (approximately 1 pint) of combine harvested wheat from each plot were collected, placed in marked re-sealable locking plastic bags, and delivered to the University of Nebraska-Lincoln Department of Agronomy and Horticulture for protein, moisture and seed counts/pound determinations.  Yields/acre were calculated and standardized using 13.5% moisture.

Data analyses

Data for each individual year were analyzed and treatment means statistically separated using Tukey’s Honestly Significant Difference (HSD) test (JMP, SAS Institute Incorporated, Cary, NC).  A paired T test for treatment effect on mean annual yields was also conducted.


Results and Discussion

Application of RyzUp SmartGrass® with Class Act® NG® resulted in significantly taller and wider wheat in this experiment at 14 and/or 21 days post treatment (Table 2).  Sampling on March 29 noted some leaf tip dessication due to freezing temperatures prior to this date.  Some wheel tracks were also noted due to application of 80 lbs./acre of actual nitrogen in the form of 46-0-0 on March 23.  


Table 2.  Mean SY Wolf hard red winter wheat standing height and width (inches) following treatment with 0.5 oz./acre of RyzUp SmartGrass® on March 8, 2016, Lancaster County, NE.


                                                       Plant height                          Plant width       

Treatment and rate/acre            March 22 March 29           March 22* March 29

RyzUp SmartGrass® 0.5 oz.          8.2a        9.0a                  5.6a            4.6a

Untreated                                       6.9 b       8.1 b                 5.3a            4.2 b

                 P value                       0.0015        0.04                 0.36           0.0043


Means in columns followed by the same letter are not significantly different at the p<0.05 level (Tukey’s HSD test, JMP 10.0.0).

* Samples on this date were canopy width, samples from later date were widths of solid green                    



Growth differences were readily visible by 14 days post treatment on March 22, 2016.   Treated areas, and especially the smaller plants, had a ‘yellowish’ appearance on this date associated with rapid growth which was evident even at a distance (Figure 2).


Figure 2.  Field strips of RyzUp SmartGrass® treated wheat were visibly less green at two weeks post application in 2016, thought due to the more rapid growth and associated reduced chlorophyll content.


While plant biomass was not measured in this experiment, the differences noted in 2016 indicate that usage of RyzUp SmartGrass® provide additional early wheat forage for producers who wish to graze this crop in addition to grain production, as a much more uniform forage height was noted in treated plots (Figure 3).  Such differences were not noted in 2017.  It is unknown if the lack of such differences in 2017 was due to application of fertilizer to all plots and/or the lack of surfactant used in 2016.

Figure 3.  Wheat treated with RyzUp SmartGrass® in 2016 (foreground) was lighter colored and more uniform in height and width at 14 days post treatment than untreated wheat (far left rows, area to right of treated wheat).



Application of RyzUp SmartGrass® was noted to result in 2.5% more yield in both years.  A significant 3.3 bushel/acre yield increase was documented in 2016, and a non-statistical increase of 3.5 bushels/acre was noted in 2017 (Table 3).  Application of RyzUp SmartGrass® was noted to result in much less variation in yields between treated plots compared to untreated wheat. The mean yield increase over both years due to RyzUp SmartGrass® was statistically significant using a paired T Test (p = 0.019).

RyzUp SmartGrass® application did not affect percent moisture at harvest or percent protein. A trend for more calculated seeds/acre was observed in both years, with the increases being over 3.5 million seeds/acre in 2017 and approximately 8.0 million in 2016 (Table 3).  These data indicate that the yield increases are attributed to increased number of seeds/acre rather than larger seeds.   Further increases in yields could potentially be gained from RyzUp SmartGrass® application, but may require additional nutritional inputs to be realized. 


Table 3.  Mean SY Wolf hard red winter wheat yields, seed count/lb., and percent protein (all standardized to 13% moisture) and percent moisture at harvest following treatment with RyzUp SmartGrass® March 2016-2017, Lancaster County, NE.

Treatment and Rate/Acre

% Moisture

at Harvest



acre @ 13.5% H20)

Percent Protein






RyzUp SmartGrass® 0.5 oz. 12.7 a 86.7 a  13.8 a 14,444 a  74.7 a
Untreated 12.8 a 83.4  b 12.8 a 13,458a  66.7 a
                  P value 0.51 0.03 0.11 0.08 0.07
RyzUp SmartGrass® 0.46 oz. + Fertilizer 12.4 a 77.0 a 12.9 a 13,181 a   63.76 a
Fertilizer only 12.5 a 73.5 a 13.4 a 13,636 a 60.02 a
       P value 0.104 0.13 0.36 0.34 0.068
Means in sub-columns followed by the same letter are not statistically different at the 00.5 level (Tukeys HSD test, JMP 13.0.0).  




Most experimentation RyzUp SmartGrass® has been with the 0.5 oz./acre rate. Product labeling for Nebraska indicates a use rate of 0.3–0.6 oz./acre as a foliar application, and supplemental labeling for New York allows a top rate of 1.0 oz./acre on wheat.  It is unknown if wheat yields would be even further increased by using higher rates of RyzUp SmartGrass®.  

Wheat growth stage also appears to be a potential critical factor, as negative results were noted when applied at green-up in North Carolina (Weisz, 2014), but positive when applied later in development at the 3 leaf stage in Nebraska and Washington.  Additional research is also needed to document the best growth stages for wheat response to RyzUp SmartGrass® and/or the increased value as a grazed forage prior to grain production.


Literature Cited

Bruynis, C.  (2014).  Wheat Grain Yield Response to RyzUp SmartGrass®.  2 pages.

Rethwisch, M.D, and C.J. Hruska.  (2016).  “WB-Cedar” Hard Red Winter Wheat Response to Early Spring 2014 Application of RyzUp SmartGrass® and Generate®.  6 pp.‑%20RyzUp%20and%20Generate%20Report.pdf

Rethwisch, M.D., C. Hruska, G. Tooker, K. Scheffler, and A. Meusch. (2017).  Smooth brome (Bromus inermis) growth response to RyzUp SmartGrass is effected by surfactant. P. 26. In Proc. National Association of County Agricultural Agents 102nd Annual Meeting and Professional Improvement Conferences. July 9-12, 2017, Salt Lake City, UT.  192 pp.

Rethwisch, M.D., G. Tooker, S. Willet and C. Hruska.  (2014).  RyzUp SmartGrass® effects on smooth brome growth and yields.  Pp. 136-143.   In Proc. 41st (2014) Plant Growth Regulation Society of America, San Francisco, CA.  164 pp.‑SmartGrass‑Effects‑on‑Smooth‑Brome‑Growth‑and‑Yields.pdf                       

Weisz, R.  (2014).  Soil conditioners, amendments, additives, and plant growth regulators wheat 2013-14 test results. North Carolina State University.  SmartGrains - The Small Grains Fact Sheet.  No.35.  4 pp.

Zugar, R.J., D. Appel, and I.C. Burke.  (2020).  Weed Control with Fierce and RyzUp Smartgrass (GA3) in Winter Wheat.  3 pp.