Articles

Penn State Weed Science Herbicide Trials Overview

Penn State weed scientists conduct various herbicide trials on new and existing products. This provides an overview of the experiments we conducted in the 2025 season.

Save for later Print

Updated:

March 4, 2026

Skip to the end of the images gallery

An herbicide trial at Penn State’s Agronomy Research Farm. (D. Lingenfelter, Penn State Weed Science)

Skip to the beginning of the images gallery

Principal Investigator and Co-Investigator

Dwight Lingenfelter, Extension Weed Scientist, and John Wallace, Ph.D., Penn State Extension Weed Management Specialist and Associate Professor

Background

Periodically, we receive inquiries about the range of herbicide field trials we conduct at Penn State. Many of our trials are company-sponsored protocols in corn and soybean. However, others include small grains, pastures/hayfields, sorghum, and even some vegetable crops. Some focus on burndown programs, 1-pass vs. 2-pass programs, or application timings, while others are to simply learn about a new experimental herbicide. Also, several studies each year result from conversations about emerging weed-related issues that we have with farmers and others in the ag industry. From these interactions, we develop our own treatment lists to obtain the necessary data. Below is a brief overview of the various herbicide field trials we conducted this past year. More information is available upon request.

Objective

The research objective was to evaluate the effect of various herbicide programs on weed control, crop injury, and yield.

Methods

Most of these experiments were conducted on small plots (10 feet by 30 feet) and replicated three times. Herbicides were applied with a small-plot, CO₂-backpack sprayer system that delivered 15 GPA through TeeJet nozzles. Visual ratings were taken during the season and yield data were collected when necessary.

Results

Corn Trials

Resicore Rev and Kyro programs in reduced till corn

This study evaluated different residual products such as Resicore Rev followed by Kyro programs or Resicore Rev in a 1-pass EPOST program. Resicore Rev is an updated formulation of Resicore. Kyro is an encapsulated formulation of acetochlor (Enversa) + topramezone (Impact) + clopyralid (Stinger).

Surtain programs applied EPOST in reduced till corn

This study examined Surtain that contains pyroxasulfone (Zidua) plus saflufenacil (Sharpen) in an encapsulated formulation for residual weed control. It was compared to other commercial standards in primarily 1-pass EPOST programs. Because of its formulation, Surtain does not have burndown activity on weeds, so burndown herbicide will need to be added to the program.

Competitive herbicide programs shootout in reduced till corn (Syngenta, FMC, others)

This is a comparison study of various industry standard programs to demonstrate the difference in weed control between 1-pass PRE only programs with 2-pass (PRE followed by POST) programs. Some also include residual herbicides in the POST application to extend weed control later into the season.

Effect of Group 15 herbicides (Dual II Mag. & Warrant) at different application timings in corn

This is a multi-state study that resulted from comments made by various farmers and consultants around the country who claim that Group 15 herbicides result in crop injury and thus yield loss. The premise of the study was to compare Dual II Magnum and Warrant at different crop stages (PRE, EPOST, and MPOST) either applied alone or in sequence. Preliminary data from this study and the combined data suggest there is no impact on yield from either of these products even though some initial crop injury may be evident.

Convintro (experimental) programs compared to competitive standards in reduced till corn

Convintro (group 12; Bayer) with the active ingredient diflufenican does not have a new mode of action but is unique to the North American market and cropping systems. It has bleaching action on weeds and can cause transient crop injury. This injury is evident as white leaves and stems. Bayer plans to initially market it in corn and soybean, and its primary targets are Palmer and waterhemp and few other broadleaves. It suppresses annual grasses but is weak on ragweed. It will be used PRE with low use rates and will be mixed with other products to broaden the weed control spectrum. The herbicide does not have EPA approval yet, but possibly soon.

Burcucumber herbicide program comparisons in no-till corn (strip trial)

This was a continuation of annual studies that evaluate different herbicide programs and application timings to better manage burcucumber in corn. Peak-containing programs continue to be the most consistent for season-long control. Other programs can be adequate and allow for rotation to soybean next season.

Soybean Trials

Programs containing Enversa and other residuals in reduced till E3 soybean

In this study, Enversa (micro-encapsulated acetochlor) was applied in various combinations with Enlist One, Liberty, and glyphosate at the PRE, EPOST, and MPOST growth stages to evaluate crop safety and weed control. Also in the study, Sonic Boom (sulfentrazone + metribuzin) was tested against Sonic and Kyber Pro.

Competitive programs in reduced till E3 soybean

This was a competitive demonstration between various herbicide treatments and timings to showcase the difference between them. Most of the programs were focused on Syngenta and BASF portfolios but a few other products were included in the programs.

Effect of Group 15 herbicides (Dual Mag. & Warrant) at different application timings in soybean

This was a multi-state study like the one in corn. Preliminary data from this study and the combined data suggest there is no impact on yield from either of these products even though some initial crop injury may be evident.

Convintro (experimental) programs compared to competitive standards in reduced till soybean

Similar to the study in corn, Convintro was applied in soybean programs. Soybeans tend to be more sensitive to this herbicide. They showed more initial bleaching of the leaves, but it subsided during the growing season.

FMC concept programs in reduced till soybean

This study evaluated several FMC products and programs in a 2-pass system. It also included an experimental premix that could potentially be applied either PRE or POST.

Liberty Ultra: time of day demo

This demonstration showcased the effectiveness of the new glufosinate formulation of Liberty Ultra when applied at five different times from dawn to dusk. It is well documented that glufosinate activity on weed control can be influenced by various environmental factors including temperature, humidity, sunlight, dew on leaves, and other factors. This study showed that these factors impacted weed control depending on the time of application. The dawn application had reduced activity.

Burndown Trials

Preplant burndown programs in E3: Rapidicil/Fierce vs. others

This study compared a new Valent experimental PPO inhibitor in programs vs. competitive standards. Rapidicil (epyrifenacil; group 14) is an experimental PPO inhibitor herbicide like Sharpen and has activity on many annual broadleaves and certain grasses. However, it is weak on marestail.

Voraxor (BAS851) burndown efficacy with auxin or residual tank mix partners

These studies evaluated different tank mix partners including glyphosate and Enlist One to enhance burndown activity of their new experimental product Voraxor. Different residual tank mix partners including Zidua SC, Boundary, and Matador-S. Voraxor (saflufenacil [Sharpen] + trifludimoxazin [Tirexor]; group 14) will primarily be used as a burndown before corn, soybean, small grains, and likely other crops.

Helm (HAI-333) experimental burndown programs

This study evaluated an experimental premix that included the active ingredient found in Reviton. It was tank mixed with other herbicides to determine effectiveness on burndown activity.

Value of ALS in burndown of marestail at different sizes in soybean

This trial examined the burndown effectiveness of certain ALS (Group 2 – FirstRate and Classic) herbicides on ALS-resistant marestail control at different sizes (rosette, 3 and 6 inches tall). Despite the population being resistant, these ALS herbicides still provided some suppression, especially when applied in its early stages of growth. However, Sharpen still tends to provide the most consistent control of marestail.

Small Grain/Forage Trials

Effect of herbicides on spring oat injury and weedy grass control – 2025

Weedy annual grasses (e.g., foxtails, crabgrass) can be a problem in spring oats. In the Mid-Atlantic, there are no herbicides that are labeled for use in oats that will provide consistent control of these grassy weeds. Potential herbicide candidates include Prowl H2O, Dual II Magnum, and diuron. Although Optogen (bicyclopyrone) and Shieldex exhibited minimal crop injury by late season, their weed control was generally inadequate. Zidua SC/Anthem Flex, PowerFlex HL, and Osprey caused significant oat injury and thus are not viable options.

Control of smooth bedstraw in pasture/hayfields – 2025

Smooth bedstraw is a problem in many pastures and hayfields. There are few herbicides that provide effective control, and application timing can be challenging too. GrazonNext, PastureGard, and Crossbow tend to be the most consistent. However, the utility of GrazonNext can be difficult due to its residue issues in hay and manure, so PastureGard and Crossbow would likely be the best options in hay settings. In this study, summer applications tended to be the best time to spray. However, spring applications can provide suppression too. Fall applications were applied but weed control efficacy will be evaluated next spring. 2,4-D, dicamba, NovaGraz, and metsulfuron were not effective at controlling smooth bedstraw.

Effect of Envu experimentals vs. others on weedy annual grass control POST in grass pastures

Weedy grasses such as foxtail, large crabgrass, Japanese stiltgrass, Johnsongrass, roughstalk bluegrass, and others are becoming a problem in grass forages. Currently, there are no effective POST herbicides that provide control of these and other grass species in a grass forage setting. Prowl H2O, QuinStar, and GrazonNext have some activity on weedy grasses. However, not all species are controlled, and there can be issues with application timing, product cost, and other negative factors. If registered, Envu has some experimental herbicides that could help control weedy grasses and maintain grass forages.

Conclusion

This work shows that we conduct many different herbicide trials at Penn State to stay current with new products and emerging weed management issues. Data from any of these trials are available in our Penn State 2025 Herbicide Field Trials – Volume 35 Final Report.