Court admits the testimony of Agriculture Expert Witness after establishing it is not conduit testimony from an expert on a matter outside his field of expertise

Court admits the testimony of Agriculture Expert Witness after establishing it is not conduit testimony from an expert on a matter outside his field of expertise

This case involved soybean farmers Jerry and Frances Probasco suing agricultural cooperative MFA Incorporated and employee Nick Riihinen for negligence, breach of contract, and breach of warranty after herbicide sprayed on their crops by MFA allegedly killed 162 acres of soybeans. The case was heard in the United States District Court for the Southern District of Iowa, Central Division.

In the spring of 2021, the Probascos had planted 185 acres of Channel® XtendFlex® Soybeans, tolerant to dicamba, glyphosate, and glufosinate but not 2,4-D. Around July 20, 2021, MFA and Jerry Probasco had discussed the cost of MFA spraying Liberty and Roundup herbicides on the Soybeans. MFA had recommended a residual herbicide, Warrant, without inquiring about the Probascos’ post-harvest cover crop plans or warning about limitations. 

Around July 21, 2021, Nick Riihinen, MFA’s spray applicator, sprayed herbicides, including 2,4-D, on most of the Probascos’ Soybeans. Shortly after, the Soybeans sprayed by Riihinen died. By July 26, 2021, the Probascos had noticed the absence of the Channel seed sign at the field entrance of the Probasco’s property. Despite MFA’s awareness that the Soybeans were Channel® XtendFlex®, intolerant to 2,4-D, they had been sprayed with this herbicide, resulting in the death of almost all Soybeans. 

During discovery, Plaintiffs had identified two expert witnesses: John Bos and Katie Ahlstrom. Bos had observed the dead soybean crops and sent a sample of the crops to a lab for testing. Plaintiffs had intended to propound opinion testimony regarding the cause of the damage he observed. During his deposition, Bos had testified that he suspected 2,4-D caused the soybean crop to die based on how quickly the crop had died after being sprayed. He had begun forming this opinion before receiving lab results.

Katie Ahlstrom, who works at South Dakota Agricultural Laboratories, had received the sample Bos took and tested it for 2,4-D and glufosinate. She had memorialized her test results in the Report, including measuring the parts per billion of each of those substances. If called to testify, Plaintiffs would have elicited three opinions from Ahlstrom: (1) the sample was received and stored using proper protocols, (2) the testing methods were scientifically acceptable, (3) and the quality control results for the tests were within acceptable limits.

Before the Final Pretrial Conference, there had been a miscommunication between the parties regarding stipulations in the proposed Final Pretrial Order. Initially, the parties had tentatively agreed to stipulate that 2,4-D killed the soybeans. At the time of that agreement, Bos and Ahlstrom were both listed on Plaintiffs’ witness list. Subsequently, Plaintiffs removed Ahlstrom from their witness list in reliance on the expected stipulation regarding 2,4-D. However, when Defendants noticed Ahlstrom’s removal from the witness list, they decided not to stipulate to 2,4-D as the cause of death for the soybeans. Instead, Defendants filed their Motion in Limine to preclude Bos from testifying to the contents of the Report. Both sides were allowed to, and did, file supplemental briefs on the narrow question of Bos’s ability to testify about the Report. Defendant argued in supplemental briefs that Bos was not qualified to testify as to matters contained in the Report. In contrast, Plaintiffs contended that Fed. R. Evid. 703 allowed Bos to rely on and interpret the Report to support his opinion that 2,4-D killed the soybeans.

Agriculture Expert Witness

John Bos is the owner of Crop Services, Inc., an Agricultural Supply and Fertilizer Dealer located near Drakesville, Iowa. He is a licensed chemical dealer and custom applicator with over 49 years of experience. 

Discussions by the Court

The admissibility of expert testimony is governed by Fed. R. Evid. 702, which stated that a qualified expert could testify if their knowledge, skill, experience, training, or education would help the trier of fact understand the evidence or determine a fact in issue. Rule 702 served a “gatekeeping function” to ensure scientific testimony was relevant and reliable. Pursuant to Rule 703, an expert could rely on otherwise inadmissible hearsay evidence if reasonably relied upon by experts in the field. But a party cannot call an expert simply as a conduit for introducing hearsay under the guise that the testifying expert used the hearsay as the basis of his testimony.

When it ruled in open Court on the motion in limine, the Court had not fully appreciated the interplay between Bos’s opinion and Ahlstrom’s Report. The Court had mistakenly believed that Bos needed Ahlstrom’s Report to confirm the presence of 2,4-D in the soybean sample. In reality, as the Court later understood, Bos already knew the sample would have 2,4-D because Plaintiffs and Defendants alike agreed that the soybeans were sprayed with 2,4-D shortly before they died. Thus, as it related to the concentration of 2,4-D in the soybean sample (measured, apparently, in parts per billion), Ahlstrom’s Report simply transmitted data that an expert like Bos commonly would rely upon when forming an opinion. Bos was allowed to rely on this data without Ahlstrom herself testifying.The reasonableness of Bos’s reliance on such data went to the weight, not the admissibility, of his opinions

Had Ahlstrom herself testified, Plaintiffs would have elicited three opinions from her: (1) the sample was received and stored using proper protocols, (2) the testing methods were scientifically acceptable, (3) and the quality control results for the tests were within acceptable limits. Plaintiffs had represented that they did not intend to offer into evidence the letter dated September 14, 2022, in which Ahlstrom stated these three opinions. Moreover, although Bos could testify that it was customary for experts in his field to send samples to a laboratory for testing and rely on the results of that testing, the Court had understood that he did not intend to testify to Ahlstrom’s three opinions, either. In other words, he would not “parrot” her opinions about the reliability of the testing, but rather simply would use the data regarding the concentration of 2,4-D to support his opinion on causation. This was within the scope of admissible expert testimony.


The Court denied MFA’s motion in limine and permitted Bos to rely upon, and testify about, Ahlstrom’s Report to the extent set forth above.

The Court, on its decision dated October 24, 2023, ruled in favor of Defendant MFA Incorporated regarding the Plaintiffs’ claim of breach of contract. However, the Court sided with Plaintiffs Jerry and Frances Probasco on their claim of breach of implied warranty of fitness for a particular purpose. Additionally, the Court favored Defendant MFA Incorporated on the Plaintiffs’ claim of negligence. Regarding comparative fault, the jury determined that Jerry and Frances Probasco were 70% at fault, while Defendant MFA Incorporated was found to be 30% at fault.

Key Takeaways

This case demonstrates that under Federal Rule of Evidence 703, an expert witness can rely on and testify about hearsay evidence, like the lab report here, in forming an opinion, if it is the type of evidence reasonably relied upon by experts in that field. However, conduit testimony from an expert on a matter outside his field of expertise is considered inadmissible.

The Court allowed the expert here to rely on quantitative lab data showing the concentration of chemicals found in the crop samples he submitted for testing. But the Court prohibited him from testifying about the testing methodology or opining on the validity of the lab procedures and protocols, as he lacked expertise on those matters. 

Overall, this case underscores the importance of tying expert opinion testimony to the witness’s specific expertise. While an expert can reasonably rely on certain otherwise inadmissible hearsay evidence in forming opinions, the expert cannot simply repeat hearsay opinions or information outside his or her expertise. Drawing this line is key to ensuring expert opinion testimony satisfies the reliability and relevance requirements under the Federal Rules of Evidence.