Helena Chemical Company v. Robert Cox

Supreme Court of Texas

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No. 20-0881

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Helena Chemical Company,

Petitioner,

v.

Robert Cox, et al.,

Respondents

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On Petition for Review from the

Court of Appeals for the Eleventh District of Texas

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Argued October 26, 2022

JUSTICE BLACKLOCK delivered the opinion of the Court.

JUSTICE YOUNG did not participate in the decision.

The plaintiffs are farmers who claim that an aerial herbicide

drifted onto their farms and damaged their cotton crops. The defendant

is Helena Chemical Company, which oversaw the aerial application of

herbicide that the farmers blame for the damage. The district court

granted summary judgment for Helena, but the court of appeals

reversed. This Court is now asked whether the evidence that Helena’s

application of herbicide caused the plaintiffs’ injury raises the genuine

issue of material fact required to survive summary judgment. As

explained below, we agree with the district court that it does not. The

court of appeals’ judgment is affirmed in part and reversed in part, and

the summary judgment for Helena is reinstated.

I.

A.

The plaintiffs farm cotton in Mitchell County.1 Defendant Helena

distributes an herbicide called Sendero, which is primarily used to kill

mesquite trees. Sendero contains two active ingredients—clopyralid

and aminopyralid. These ingredients are used in many other products,

but their use in combination is apparently unique to Sendero.

The plaintiffs allege that Helena supervised an aerial application

of Sendero over several non-contiguous parcels of the Spade Ranch, a

large ranch spanning parts of Coke, Sterling, and Mitchell Counties.

Two planes sprayed roughly 3,300 gallons of Sendero over several days

in July 2015. The spray was released from eight to ten feet above the

treetops. The plaintiffs allege that the herbicide drifted onto their

properties and damaged cotton crops planted in 2015 and 2016.

The plaintiffs blame Helena for reduced crop yields in over 14,000

acres of cotton fields scattered across hundreds of square miles of

Mitchell County. These fields are located between 1.8 miles and 25

miles from the places on the Spade Ranch where Helena sprayed

Sendero. The precise locations of the allegedly affected fields are not

1 The plaintiffs are Robert Cox, James Cox Trust, Cox Farms, Tanner

Cox, Loren Rees, Tyson Price, Russell Erwin, David Stubblefield, Rushnell

Farms, Brooks Wallis, Hoyle & Hoyle, and Jack Ainsworth.

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entirely clear from the record, which contains only a high-altitude map

showing color-coded parcels identifying most of the plaintiffs’ fields. The

placement of the fields follows no discernable pattern. Some fields are

bunched together, while some are isolated by many miles.

After Helena’s application of Sendero over the Spade Ranch, the

plaintiffs complained of crop damage. Texas Department of Agriculture

(TDA) inspector Cory Pence investigated the incident in July 2015. He

concluded that the Spade Ranch application of Sendero was a possible

cause of the plaintiffs’ crop damage. He claimed to find “markers” for

both aminopyralid and clopyralid. He was unable, however, to identify

a “consistent pattern” or “drift pattern” of crop damage over this large

area. Pence conducted only a visual inspection, and TDA never

conducted any laboratory tests for aminopyralid or clopyralid. When

deposed, Pence could not explain the difference between markers for

aminopyralid and clopyralid.

The plaintiffs allege that Sendero is highly toxic to cotton plants

and should only be applied when the risk of drift onto nearby, sensitive

areas is minimal. Warnings on Sendero’s label say as much, and Helena

does not contend otherwise. The plaintiffs allege that weather

conditions—including wind, temperature, and humidity—were such

that Sendero should not have been sprayed on the days in question.

They further allege that application of the herbicide at an

inappropriately high altitude resulted in greater drift onto neighboring

properties.

The plaintiffs harvested and sold what they could from their 2015

crops. They gathered only limited evidence of the herbicide damage,

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either at the time they noticed it or at the time of harvest. Notably,

many of the plaintiffs filed insurance claims attributing their crop losses

to drought or other adverse weather. The record contains three

photographs of allegedly damaged crops. These photos come from

unidentified fields and were taken on unknown dates.2

B.

The plaintiffs sued Helena and other defendants in 2015 in

Mitchell County. They sought recovery under various theories for the

reduced cotton crop produced by their land in 2015 and 2016, as well as

mental-anguish damages and punitive damages.

Helena filed several dispositive motions. The district court

granted Helena’s motion for partial summary judgment as to mental

anguish, gross negligence, and punitive damages. Helena also filed a

no-evidence motion for summary judgment, arguing that no evidence

supported the element of causation essential to recovery under all the

plaintiffs’ claims. Helena simultaneously filed a motion to strike the

plaintiffs’ expert opinions on causation, arguing that the opinions were

unreliable and therefore inadmissible. Helena further contended that

even if the experts’ opinions were admitted, they would constitute no

evidence of causation, requiring summary judgment for Helena.

2 Plaintiffs’ experts Ronald Halfmann and Tracey Carrillo, whose

opinions are discussed below, attested that they had reviewed “hundreds” of

photographs of crop damage in Mitchell County, but these photographs are not

in the record, which is silent as to the dates, the precise locations, or any other

specifics regarding the crop damage depicted in the photographs reviewed by

the experts.

4

The plaintiffs retained five experts whose testimony bears on

causation: Ronald Halfmann, Tracey Carrillo, Daylon Royal, Paul

Rosenfeld, and Paul Ward. Their affidavits, expert reports, and

deposition testimony are part of the record and were the focus of the

no-evidence summary-judgment motion and the motion to strike.3 The

experts did not visit the affected fields or collect cotton samples. They

relied on reports from TDA inspector Pence and from the plaintiffs, as

well as on other available information.

Ronald Halfmann is a former inspector with the TDA. He

identified himself as an expert “in agricultur[al] application of

pesticides” with “extensive experience investigating pesticide drift.” He

opined that Helena breached the standard of care for use of aerial

herbicides, that weather conditions and faulty application techniques

caused excessive drift, and that the Spade Ranch application of Sendero

damaged 15,000 acres of cotton as claimed by the plaintiffs. He stated

that Sendero can drift up to 20 miles under hazardous weather

3 A separate group of plaintiffs sued Helena in Reagan County. The

lawyers in that case and in this case agreed that certain expert affidavits and

depositions could be used in both cases. Although they did not so argue in the

district court, the plaintiffs now contend that this Rule 11 agreement restricted

Helena’s right to challenge the reliability of the experts’ testimony. We

disagree. We read the agreement as intended to eliminate needless duplication

of discovery and to permit the use of the expert opinions insofar as they recite

the experts’ “qualifications and experience,” the “methodology employed” by

the experts, and the “scope and extent” of the opinions. We do not read the

agreement as intended to waive Helena’s right to challenge the substance of

the experts’ opinions as unreliable. The attorneys who executed the agreement

did not argue in the district court that the agreement has the effect now

claimed.

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conditions and that, in his opinion, only a large application of herbicide

would have caused the damage reported by the plaintiffs.

Tracey Carrillo is an agronomist and entomologist. He has many

years of experience in cotton farming and herbicide drift. In his opinion,

damage from Sendero occurred in all the plaintiffs’ fields. He based this

opinion on the Sendero label, plant tissue samples that were tested for

clopyralid and aminopyralid, observations from the farmers, the report

of TDA investigator Pence, and other information. He explained that

damage to cotton fields from Sendero is prolonged and substantial and

that damage from aerial-drift events is widely known and accepted. He

opined that crop damage in 2015, 2016, and 2017 was consistent with a

large-scale application of Sendero. He concluded, based on his review of

the evidence, including lab test results, that “there is no doubt that [the

plaintiffs’] cotton was contaminated from spray drift of applications of

Sendero conducted by [Helena].”

Daylon Royal is a crop-dusting pilot. He also addressed physical

drift. He advised Carrillo that it was highly probable that Helena’s

application of Sendero had caused the herbicide to drift onto the

plaintiffs’ fields because of wind and temperature conditions at the time.

He relied on a “rule of thumb” that as much as 50% of aerially applied

pesticide drifts away from the targeted field.

Paul Rosenfeld is an environmental chemist who has studied the

effect of Sendero on crops. He provided evidence that Sendero results in

long-term damage to cotton fields. Based on Pence’s TDA report and

other information, Rosenfeld concluded that Sendero drifted onto the

plaintiffs’ farms and damaged their cotton crops. He testified that

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Helena’s 2015 Sendero application would remain in the soil and damage

the plaintiffs’ crops in 2016.

Paul Ward grew bean plants in soil samples taken from Mitchell

County and compared them to samples grown in potting soil. He had no

prior experience evaluating herbicide exposure and no experience with

Sendero, clopyralid, or aminopyralid. He did not know whether any

scientific studies confirmed that his methods were reliable to show what

actually happens in cotton fields.

The district court held an extensive hearing on the motion to

strike the expert testimony. It later granted the summary-judgment

motion and the motion to strike and rendered judgment for Helena. The

court of appeals reversed, in large part. 630 S.W.3d 234, 249 (Tex.

App.—Eastland 2020). It reasoned:

Although Halfmann, Carrillo, and Rosenfeld could not

specifically trace the purported drift of clopyralid from the

Spade Ranch to Appellants’ cotton fields, they provided a

reliable scientific basis for their opinions that Appellants’

cotton crops were damaged by a large-scale aerial

application of clopyralid to the south of Appellants’ fields.

Relying on Pence’s investigation and observations that

Helena’s aerial application of Sendero, which was done in

conditions that exacerbated drift, was the only such

large-scale application at the relevant time and place, they

concluded that the damage to Appellants’ cotton crops was

caused by Helena. We see no analytical gap in such a

conclusion. We sustain Appellants’ second issue as to

Appellants’ expert witnesses with one exception: that

exception being Royal’s attempt to offer an opinion that

Sendero drifted from Helena’s application site to

Appellants’ fields.

Id. at 243–44. Because it concluded that the experts’ evidence was

reliable and therefore admissible, the court of appeals also concluded

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that there was evidence of causation sufficient to survive summary

judgment. Id. at 244–45.

The court of appeals did, however, agree with Helena that it was

entitled to partial summary judgment as to claims for mental anguish

and punitive damages. The plaintiffs do not challenge the court of

appeals’ affirmance of summary judgment in this regard. After

affirming in part and reversing in part, the court of appeals remanded

the case to the district court for further proceedings. Id. at 249. Helena

petitioned for review in this Court, and we granted the petition.

II.

A.

A party may move for summary judgment, after adequate time

for discovery, “on the ground that there is no evidence of one or more

essential elements of a claim or defense on which an adverse party

would have the burden of proof at trial.” TEX. R. CIV. P. 166a(i). The

court must grant such a “no-evidence” motion unless the non-moving

party responds with “evidence raising a genuine issue of material fact.”

Id. Appellate courts review summary judgments de novo. Valence

Operating Co. v. Dorsett, 164 S.W.3d 656, 661 (Tex. 2005). In so doing,

we examine the evidence in the light most favorable to the non-moving

party, indulging reasonable inferences and resolving doubts against the

party seeking summary judgment. City of Keller v. Wilson, 168 S.W.3d

802, 824 (Tex. 2005).

The issue before this Court is whether the plaintiffs’ evidence

raised a genuine issue of material fact on causation, which is an

essential element of all the plaintiffs’ claims on which they bear the

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burden of proof. To survive summary judgment, the plaintiffs’ causation

evidence must raise a genuine fact issue as to whether it is more likely

than not that Helena’s application of Sendero in July 2015 caused a

reduced yield of cotton and therefore reduced income for the farmers.

The central inquiry—viewed either through the lens of a motion

to strike the evidence or a summary-judgment motion—is whether the

plaintiffs’ experts offered reliable evidence of causation. As for the

motion to strike, “[a]dmission of expert testimony that does not meet the

reliability requirement is an abuse of discretion.” Cooper Tire & Rubber

Co. v. Mendez, 204 S.W.3d 797, 800 (Tex. 2006). As for the

summary-judgment motion, if the expert’s opinion is not reliable, it is

no evidence and will not defeat a no-evidence motion for summary

judgment. Seger v. Yorkshire Ins. Co., 503 S.W.3d 388, 410 n.23 (Tex.

2016) (“Unreliable expert testimony is legally no evidence.”); Merrell

Dow Pharms., Inc. v. Havner, 953 S.W.2d 706, 713 (Tex. 1997) (“If the

expert’s scientific testimony is not reliable, it is not evidence.”). To

resolve this appeal, we will assume the experts’ opinions have been

admitted, and we will ask whether these opinions are reliable evidence

of causation sufficient to overcome Helena’s motion for summary

judgment.

A witness may be qualified to testify as an expert based on his

“knowledge, skill, experience, training, or education.” TEX. R. EVID. 702.

Although an expert witness need not always be formally credentialed as

a scientist, expert testimony on scientific matters—such as the aerial

drift of herbicide particles or the effect of herbicide exposure on plants—

naturally must be “grounded ‘in the methods and procedures of science.’”

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E.I. du Pont de Nemours & Co. v. Robinson, 923 S.W.2d 549, 557 (Tex.

1995) (quoting Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 590

(1993)); see also Gammill v. Jack Williams Chevrolet, Inc., 972 S.W.2d

713, 721–22 (Tex. 1998) (discussing reliability analysis for scientific

opinion based on witness’s skill, experience, or training). Unreliable

testimony, by contrast, includes that which “is no more than ‘subjective

belief or unsupported speculation.’” Robinson, 923 S.W.2d at 557

(quoting Daubert, 509 U.S. at 590). “If the expert brings only his

credentials and a subjective opinion, his testimony is fundamentally

unsupported and therefore of no assistance to the jury.” Cooper Tire,

204 S.W.3d at 801. The mere ipse dixit of the expert—that is, asking

the jury to take the expert’s word for it because he is an expert—will not

suffice. See City of San Antonio v. Pollock, 284 S.W.3d 809, 816 (Tex.

2009). Instead, an expert’s conclusions must have a reliable basis other

than the expert’s say-so. And “if no basis for the [expert] opinion is

offered, or the basis offered provides no support, the opinion is merely a

conclusory statement and cannot be considered probative evidence.” Id.

at 818.

In determining the reliability of expert testimony, courts must

consider not just whether the expert’s methods are grounded in science,

but also whether the data to which the expert applies his methods are

reliable. “If the foundational data underlying opinion testimony are

unreliable, an expert will not be permitted to base an opinion on that

data because any opinion drawn from that data is likewise unreliable.”

Havner, 953 S.W.2d at 714. Moreover, “an expert’s testimony is

unreliable even when the underlying data are sound if the expert draws

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conclusions from that data based on flawed methodology. A flaw in the

expert’s reasoning from the data may render reliance on a study

unreasonable and render the inferences drawn therefrom dubious.” Id.

Likewise, “if an expert’s opinion is based on certain assumptions about

the facts, we cannot disregard evidence showing those assumptions were

unfounded.” City of Keller, 168 S.W.3d at 813.

We have also recognized that expert testimony is unreliable if

“there is simply too great an analytical gap between the data and the

opinion proffered.” Gammill, 972 S.W.2d at 727 (quoting Gen. Elec. Co.

v. Joiner, 522 U.S. 136, 146 (1997)). “We are not required . . . to ignore

fatal gaps in an expert’s analysis or assertions that are simply

incorrect.” Volkswagen of Am., Inc. v. Ramirez, 159 S.W.3d 897, 912

(Tex. 2005). “Analytical gaps may include circumstances in which the

expert unreliably applies otherwise sound principles and methodologies,

the expert’s opinion is based on assumed facts that vary materially from

the facts in the record, or the expert’s opinion is based on tests or data

that do not support the conclusions reached.” Gharda USA, Inc. v.

Control Sols., Inc., 464 S.W.3d 338, 349 (Tex. 2015) (citations omitted).

Augmenting the above standards, our decision in Robinson

identified six non-exclusive factors courts may consider in determining

whether expert testimony is reliable:

1. the extent to which the theory has been or can be tested;

2. the extent to which the technique relies upon the

subjective interpretation of the expert;

3. whether the theory has been subjected to peer review

and/or publication;

4. the technique’s potential rate of error;

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5. whether the underlying theory or technique has been

generally accepted as valid by the relevant scientific

community; and

6. the non-judicial uses which have been made of the

theory or technique.

923 S.W.2d at 557. The “Robinson factors” are not always determinative

when assessing an expert’s reliability, but even when they are not, the

court must be provided with some way of assessing the reliability of

objected-to expert testimony, apart from the expert’s credentials and

say-so. Gammill, 972 S.W.2d at 726.4

B.

“[T]he ultimate issue . . . in a toxic tort case . . . is always specific

causation—whether the defendant’s product caused the plaintiff’s

4 Amicus curiae High Plains Wine & Food Foundation, unlike the

parties, relies heavily on this Court’s decision in Pitchfork Land & Cattle Co.

v. King, 346 S.W.2d 598 (Tex. 1961). Pitchfork Land assessed expert testimony

in an aerial-drift case, but unlike the amicus, we do not understand Pitchfork

Land to require a unique “standard for measuring the legal sufficiency of

causation evidence in crop-dusting cases.” Rather than cordoning off

crop-dusting cases into a special category, we should read Pitchfork Land in

conjunction with our more recent caselaw on expert testimony on scientific

matters in toxic-tort cases, in which we have established more searching

standards for evaluating the reliability of any such testimony. Robinson, in

particular, was a landmark 1995 case that largely adopted the federal

standards articulated in Daubert and signaled the beginning of this Court’s

modern approach to expert testimony in cases alleging exposure to toxic

substances. Robinson involved facts remarkably similar to those here; the

allegation was crop damage caused by fungicide. It would be quite odd for one

approach to the reliability of expert causation evidence to apply in a case about

crop damage from herbicides, but another approach to apply in a case about

crop damage from fungicides. The reality is that cases like Daubert and

Robinson marked an important development in the courts’ approach to these

matters, which has since become settled law. It should be unremarkable to

observe that many earlier cases, including a 1961 spray-drift case, do not fully

reflect the approach to expert testimony required by Robinson and later cases.

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injury.” Bostic v. Georgia-Pacific Corp., 439 S.W.3d 332, 351 (Tex. 2014).

It is important to emphasize at the outset that the plaintiffs’ injury here

is not “damage” to cotton plants, such as wilted leaves. Instead, the

injury for which the plaintiffs seek recovery is a financial one—

decreased revenue from a reduced yield of cotton at harvest. It is

therefore not enough for the plaintiffs to show that drifting herbicides

reached their plants and “damaged” them in some way. Instead, they

must show that Helena’s application of Sendero caused their plants to

yield less cotton at harvest. They need not prove this at the

summary-judgment stage, however. To survive Helena’s motion for

summary judgment, the plaintiffs must proffer some evidence creating

a genuine fact issue as to whether Helena’s application of Sendero

caused the reduced crop yield. Draughon v. Johnson, 631 S.W.3d 81, 88

(Tex. 2021).

The plaintiffs suggest that, apart from the expert testimony on

which they rely, the lay opinions of the farmers themselves about the

source of their crop failure can provide evidence of causation sufficient

to survive summary judgment. In the context of this case, we disagree.

“Expert testimony is required when an issue involves matters beyond

jurors’ common understanding.” Mack Trucks, Inc. v. Tamez, 206 S.W.3d

572, 583 (Tex. 2006); accord Gharda, 464 S.W.3d at 348. Determining

whether a particular application of aerial herbicide substantially

contributed to the failure of crops miles away requires knowledge and

analysis of scientific matters beyond the competence of laymen.5 It goes

5See, e.g., Cerny v. Marathon Oil Corp., 480 S.W.3d 612, 620 (Tex.

App.—San Antonio 2015, pet. denied) (stating that the requirement of expert

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without saying that plants, like all living things, become sickly or die for

any number of natural and man-made reasons. And the expected aerial

migration of herbicidal particles over vast distances due to weather

conditions and spray techniques is plainly not a matter with which

laymen are generally familiar. The plaintiffs were not offered as expert

witnesses, and their lay opinions, standing alone, are insufficient to

survive summary judgment.

As another initial matter, Helena argues that the required

evidentiary showing of toxic exposure at a sufficient dose must be made

for each “field” for which the plaintiffs seek recovery. According to

Helena, “the term ‘field’ is used by the [U.S. Department of

Agriculture’s] Farm Services Agency to designate the smallest unit of

land for agricultural production.” Helena asks us to require discrete

proof of causation as to each such “field” at the summary-judgment

stage. Although the U.S.D.A.’s field designations provide a convenient

way to categorize vast swaths of farmland, we cannot say that as a

matter of law every plaintiff in a crop-loss case must proffer field-by-

field proof using the U.S.D.A.’s field boundaries. To be sure, proof of

toxic exposure at one spot on a farmer’s land is not proof of exposure

throughout all of the farmer’s land. The plaintiff must show causation

testimony is “obvious” where the “claims arise out of alleged emissions and

migration of hazardous substances”); Foust v. Estate of Walters, 21 S.W.3d 495,

505 (Tex. App.—San Antonio 2000, pet. denied) (“A negligence claim against

an aerial applicator [of herbicide] must be established with expert testimony.”);

Hager v. Romines, 913 S.W.2d 733, 734–35 (Tex. App.—Fort Worth 1995, no

writ) (“We find that the standard of care in the aerial application of herbicide,

as well as the violation of such standard, must be established by expert

testimony.”).

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for the entire area for which he seeks recovery, and using the U.S.D.A’s

field designations may be a useful way to do so. But how a plaintiff goes

about making that proof—or how a defendant goes about opposing it—

need not in every case invoke the field boundaries defined by the federal

government.

C.

In a toxic-tort case alleging human exposure to harmful

substances, the “minimal facts necessary to demonstrate specific

causation” include “[s]cientific knowledge of the harmful level of

exposure to a chemical, plus knowledge that the plaintiff was exposed to

such quantities.” Builder Servs. Grp., Inc. v. Taylor, No. 03-18-00710-

CV, 2020 WL 5608484, at *6 (Tex. App.—Austin Sept. 17, 2020, pet.

denied); see also Robinson, 923 S.W.2d at 557. What is true of injured

plaintiffs in a toxic-exposure case is also true of injured crops in an

herbicide-drift case. There must be reliable evidence that the failed

crops for which recovery is sought were more likely than not (1) exposed

to the harmful chemical, (2) at levels of exposure sufficient to cause the

lost yields alleged. In addition, there must be reliable evidence ruling

out other plausible alternative causes of the lost yields. Bostic, 439

S.W.3d at 350; Havner, 953 S.W.2d at 720. Without some scientifically

reliable evidence of these facts, the evidence of causation offered does

not rise above subjective belief and will not survive a no-evidence motion

for summary judgment. Robinson, 923 S.W.2d at 557.

We turn first to whether the plaintiffs’ evidence that their crops

were exposed to Helena’s Sendero was sufficient to survive summary

judgment. Although the “field-by-field” proof demanded by Helena is

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not required, the plaintiffs must nevertheless come forward with

reliable evidence of causation for any area for which they seek recovery.

One obvious way to begin to show toxic contamination over a widespread

area in such a case would be laboratory test results from spots

throughout the allegedly affected area, coupled with reliable evidence

that the tested areas are representative of the whole area for which

damage is claimed. Yet rather than proffer lab testing confirming the

presence of Sendero in representative areas, the plaintiffs offer only

three positive lab results indicating the presence of clopyralid at

identifiable locations. Three or four other tests indicated the presence

of clopyralid at unknown locations within the allegedly damaged

acreage.

No test indicated the presence of aminopyralid, the other active

ingredient in Sendero. The plaintiffs’ experts acknowledged that

herbicides other than Sendero contain clopyralid. Thus, the laboratory

tests do not establish the presence of Sendero—as opposed to other

herbicides—anywhere in the plaintiffs’ fields. Nevertheless, the

plaintiffs’ experts also stated that aminopyralid often does not show up

in laboratory testing because it is present in such small quantities.

Deficiencies in aminopyralid testing are a matter within the expertise

of Halfmann and Carrillo, and their opinions in this regard qualify as

some evidence, at the summary-judgment stage, that (1) lab tests

indicating positive results for clopyralid can indicate the presence of

Sendero, and (2) lab testing will not necessarily distinguish Sendero

from other herbicides.

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The problem with the plaintiffs’ lab-testing evidence, however, is

that their witnesses offered no reliable way to extrapolate from the small

number of positive lab tests any conclusion at all about the presence of

clopyralid—much less Sendero6—in the rest of the vast and scattered

acreage for which recovery is sought. Even if the lab results are some

evidence indicating Sendero’s presence in the areas with positive test

results, they are no evidence that Sendero was present anywhere else.7

This is not to say that the plaintiffs needed to test every field in

order to survive summary judgment. But they do need to show, using

reliable methodology, that the acreage for which they actually have the

kind of hard scientific data our cases typically require is representative

6 TDA inspector Pence testified that he found “markers” for clopyralid

and aminopyralid in the plaintiffs’ fields, and it appears the plaintiffs’ experts

may have relied on this statement in concluding that Sendero was present.

But Pence could not explain, at his deposition, what damage to a plant is a

“marker” of aminopyralid, as opposed to other herbicides. And none of the

plaintiffs’ experts—who relied heavily on pictures of the plants and reports

from visual inspections by the farmers—provided an additional basis for

concluding that the plants exhibited damage from Sendero, as opposed to other

products. Carrillo testified that a visual inspection, even by an agronomist like

himself, cannot distinguish between cotton plants exposed to Sendero and

plants exposed to products containing only clopyralid or other herbicides.

Plaintiffs’ experts Ward, Rosenfeld, and Halfmann agreed. Helena offered

unrebutted evidence that clopyralid is found in numerous herbicides, including

many herbicides used more commonly in the area during the summer months

than Sendero. Halfmann confirmed that herbicidal treatment of mesquite by

multiple land owners would likely occur during the summer.

7 As for the sites that tested positive for clopyralid, the causation

evidence is insufficient to survive summary judgment for the reasons explained

in Parts II.D and II.E, even if the positive clopyralid test is some evidence of

Sendero’s presence at these sites.

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of the larger area for which they seek recovery.8 They could do so,

perhaps, by showing that the location of the positive clopyralid tests

relative to the aerial Sendero application are such that the herbicide

must have drifted through other, untested areas before reaching the

tested area. They did not attempt to do this. Nor have they made any

other effort to demonstrate with reliable methodology that positive lab

results in a few places are indicative of the wider presence of clopyralid

throughout the affected area.

To help fill the gap in testing data, the plaintiffs could have

proffered a recognized model of the herbicide’s drift through the air onto

the allegedly affected properties. Such evidence could provide a reliable

indication that Helena’s product actually reached the allegedly damaged

areas. The plaintiffs’ experts did not attempt to do this, however. They

acknowledged that scientific models of aerial drift exist, but they did not

employ these models or make any effort to recreate the aerial drift that

would have occurred from the Spade Ranch given the weather conditions

on July 1–4, 2015. They acknowledged that aerial drift typically occurs

in a predictable pattern, in which fields closer to the source exhibit more

8 See Plunkett v. Conn. Gen. Life Ins. Co., 285 S.W.3d 106, 115–17 (Tex.

App.—Dallas 2009, pet. denied) (affirming no-evidence summary judgment

where expert relied on positive mold test of furniture from one unit of a

241-unit apartment complex, purported to extrapolate that test to “all property

from all units,” and failed to provide “empirical evidence or methodology”

explaining the validity of the extrapolation); Purina Mills, Inc., v. Odell, 948

S.W.2d 927, 934, 937 (Tex. App.—Texarkana 1997, pet. denied) (holding that

expert testimony was insufficient where plaintiff claimed 200 cattle were

injured by defendant’s feed due to metal contamination, only two or three cattle

were diagnosed with “hardware disease,” and experts had failed to conduct “a

methodological or technical study of all the cattle or representative samples of

the feed”).

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damage than those farther away. And they acknowledged that the

scattered pattern of steady damage in this case does not fit the usual

aerial-drift model. Yet the only analysis provided of the drift pattern is

that there was a heavy south wind on the days in question and the

affected fields are north of the Spade Ranch.9 This observation certainly

indicates the likelihood that some Sendero floated in the general

direction of the plaintiffs’ fields, but it is no evidence of causation

because it amounts to no more than speculation that Sendero actually

landed on these particular, scattered fields in a concentration sufficient

to cause the crop damage and attendant loss of yield alleged.

The only testimony offered about aerial-drift patterns was

inconclusive or speculative. Carrillo stated that there was no

discernable pattern of harm to the damaged crops that would be “a

common characteristic of physical drift.” Halfmann similarly testified

that the “patchiness of the damage” in this case could not

“scientifically . . . be explained by anyone” under a theory of drift

patterns or a drift mechanism, and that the observed “sporadic effects”

were “unexplainable.” The experts essentially expressed the view that

aerial drift must have occurred here because of the widespread damage

alleged—even though the damage pattern was not consistent with

typical drift patterns. But their conclusions in this regard lack a reliable

foundation grounded in science and amount to no more than speculation.

They offered no drift model that had been tested, cited no studies

9 Pence, who personally investigated the incident, was likewise unable

to identify any “consistent pattern” or “drift pattern” of crop damage over this

large area.

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supporting their analysis, offered no reasoned discussion of the potential

rate of error of their analysis, gave no indication that their approach to

understanding aerial drift had been accepted in the scientific

community, and could point to no non-judicial use of their methods.

Robinson, 923 S.W.2d at 557. Thus, none of the Robinson factors are

present, and the plaintiffs offer no alternative basis on which a court

could find that their expert testimony on aerial-drift patterns is

scientifically reliable. Just as in Robinson, the experts failed to present

a scientifically valid model that could explain why there was “no

consistent pattern of damage to the trees,” or in this case, the cotton

crops. Id. at 551.

We do not suggest that precision of proof is required in such a

case. Nor do we suggest a rigid requirement that such cases must

always be proved with scientific modelling of the aerial-drift pattern or

with any other precise category of evidence. But it defies reason to

suggest that Helena’s aerial application of Sendero landed in roughly

equal quantities on all 111 fields scattered across hundreds of square

miles of Mitchell County. Some scientific attempt to model where the

Sendero probably drifted, in what amounts, and why, could at least have

provided rational estimates of how much of Helena’s Sendero, if any,

reached these scattered fields. This information might enable the

plaintiffs to establish that Helena’s Sendero substantially contributed

to their losses across the entire area. Or it might narrow the area for

which the plaintiffs can obtain recovery. Either way, assignment of

liability to Helena could be based on a rational analysis bearing some

indicia of reliability—not on the kind of assumptions and speculation we

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have repeatedly deemed insufficient. See, e.g., Marathon Corp. v.

Pitzner, 106 S.W.3d 724, 729 (Tex. 2003); Cooper Tire, 204 S.W.3d at

801–07; Burroughs Wellcome Co. v. Crye, 907 S.W.2d 497, 499–500 (Tex.

1995).10

D.

A scientific model of the aerial drift—which the plaintiffs’ experts

did not attempt to offer—could also have provided evidence on another

important facet of causation in toxic-exposure cases: the dosage. We

have often articulated the requirement in similar cases that the plaintiff

establish with evidence the dosage required to produce the alleged

injury. For example, in Robinson, we held that an expert’s testimony

regarding contamination of pecan trees by fungicide was unreliable

because the expert had “no knowledge as to what amount or

concentration of [contaminants] would damage pecan trees.” 923

S.W.2d at 559. Similarly, in Cooper Tire, we held that an expert’s theory

that a tire suffered a manufacturing defect because of wax

contamination was unreliable, in part because the expert “conducted

nothing in the nature of a quantitative analysis of wax contamination,

such as calculating the amount of wax deposited on the skim stock or

10 We do not purport to be aware of all possible methods of proof in cases

such as this one. By suggesting that the plaintiffs might have raised a genuine

fact issue on causation by proffering additional types of evidence, we do not

hold that all plaintiffs in spray-drift cases must proffer such evidence to

survive summary judgment.

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the amount of wax necessary to cause a tire malfunction.” 204 S.W.3d

at 802.11

Later, in Borg-Warner Corp. v. Flores, we observed: “One of

toxicology’s central tenets is that ‘the dose makes the poison.’” 232

S.W.3d 765, 770 (Tex. 2007). We rendered judgment for the defendant

because “absent any evidence of dose, the jury could not evaluate the

quantity of respirable asbestos to which [the plaintiff] might have been

exposed or whether those amounts were sufficient to cause asbestosis.”

Id. at 771–72. Still later, in Bostic, we required proof of dose in

mesothelioma cases, even though “relatively minute quantities of

asbestos can result in mesothelioma.” 439 S.W.3d at 338. The Court

held that “proof of ‘some exposure’ or ‘any exposure’ alone will not suffice

to establish causation.” Id. Instead, “the dose must be quantified”

because “[t]he essential teaching of Flores is that dose matters.” Id. at

353, 360; see also Abraham v. Union Pac. R.R., 233 S.W.3d 13, 21 (Tex.

App.—Houston [14th Dist.] 2007, pet. denied) (“Knowledge of the extent

of exposure to a potentially harmful substance is essential to any

reliable expert opinion that the particular substance caused a disease.”)

(emphasis added).

Just as it was no answer in Bostic to say that any exposure to

asbestos can harm a person, it is no answer here to say that any

exposure to Sendero can harm cotton plants. Sendero’s product label

says that it is toxic to broad-leaf plants, which include cotton. And

11 See also Pollock, 284 S.W.3d at 820 n.33 (“[A]ny agent, even tap

water, may produce a toxic effect at a sufficiently high level of exposure,” while

“even the deadliest poison is harmless at a sufficiently low level of exposure.”).

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Rosenfeld opined that exposure as diffuse as ten parts per billion could

harm cotton. But there is simply no evidence at all in this case about

the amount of Helena’s Sendero that is alleged to have landed on the

plaintiffs’ crops miles away from the Spade Ranch. Halfmann conceded

that he had not “reconstructed how much Sendero drifted to any specific

cotton field.” Nor is there any evidence that the unspecified amount of

Sendero alleged to have landed on these fields was sufficient to make

Helena’s Sendero application a substantial factor in the lost crop yields

suffered by the plaintiffs.

Crucially, while it is undisputed that very small amounts of

Sendero can damage cotton plants, no evidence was proffered indicating

how much exposure would be required to substantially contribute to the

lost crop yields suffered by the plaintiffs. In fact, two of the plaintiffs’

experts acknowledged that cotton plants showing signs of herbicide

damage do not necessarily end up suffering reduced yield. According to

Carrillo, “It could go either way. . . . They could or could not [have

diminished yield].”12 And none of the plaintiffs’ experts knew how much

exposure to Sendero would cause reduced crop yield.

The plaintiffs do not seek recovery for wilted leaves in July. They

seek recovery for reduced cotton harvests months later, long after the

application of Sendero to the Spade Ranch. The damaged crops were

harvested and sold, although they did not produce the volume of cotton

desired. Whether Helena’s airborne Sendero was a substantial factor in

12 Rosenfeld also acknowledged that exposure to clopyralid and

resulting physical symptoms in cotton plants do not necessarily result in yield

losses, especially at low levels of exposure.

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causing the plaintiffs’ lost yield depends in part on how much Sendero

landed on the crops. It also depends on the presence of other factors

contributing to reduced yields, such as unfavorable weather (for which

the farmers made insurance claims seeking recovery of the same losses).

Without knowing how much Sendero exposure was required to produce

the plaintiffs’ injuries and without a reliable estimate of how much

Sendero landed on the fields, the factfinder could not even begin to

reasonably determine whether Helena’s Sendero—rather than

something else, such as weather or other herbicides—caused the losses.

E.

This brings us to the question of plausible alternative causes. We

have often said in similar cases that the plaintiff bears the burden to

account for such causes. “We recognized in Havner, generally, that ‘if

there are other plausible causes of the injury or condition that could be

negated, the plaintiff must offer evidence excluding those causes with

reasonable certainty.’” Bostic, 439 S.W.3d at 350 (quoting Havner, 953

S.W.2d at 720); accord JLG Trucking, LLC v. Garza, 466 S.W.3d 157,

162 (Tex. 2015); Transcon. Ins. Co. v. Crump, 330 S.W.3d 211, 218 (Tex.

2010). And in Robinson, we observed that an expert’s “failure to rule

out other causes of the damage renders his opinion little more than

speculation.” 923 S.W.2d at 559; see also Cooper Tire, 204 S.W.3d at

807–08.

Alternative causes need not necessarily be ruled out entirely,

however. In Bostic, we explained that in cases where multiple causes

might have contributed to the injury, the expert does not have to

completely eliminate the other causes as possible contributors. Instead,

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the analysis of alternative causes must be sufficient for the factfinder to

reasonably conclude that the defendant’s conduct was a “substantial

factor” in causing the injury. Bostic, 439 S.W.3d at 350–51. Nor must

the plaintiff negate every conceivable alternative cause imagined by the

defendant or the court. The testimony need only account for “other

plausible causes raised by the evidence.” Transcon. Ins. Co., 330 S.W.3d

at 218 (emphasis added).

Here, the evidence clearly indicates the plausibility of two

alternative causes—weather and other herbicides. First, none of the

experts accounted at all for the possible effect of weather on the reduced

crop yields. On this record, the undisputed fact that many of the

plaintiffs applied for insurance benefits for losses caused by weather

confirms the need for their experts to account for this plausible

alternative explanation for their losses. But the expert testimony makes

no attempt to carry this burden.

Second, the record indicates that there could have been any

number of other herbicide applications in the area, including efforts by

individual property owners or by oil and gas operators. Halfmann

acknowledged that herbicides other than Sendero are commonly used in

the area during the summer. Most importantly, the record shows that

there was another aerial Sendero application in the area. The record

contains no indication that the experts investigated or analyzed the

alternative reasons that clopyralid would have been detected in the

tested fields—or that herbicide damage would have been visually

observed—other than because of Helena’s use of Sendero.

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The plaintiffs’ evidence thus fails to account for two plausible

alternative causes—weather and other herbicides—either of which

might wholly explain the damage or render the defendant’s contribution

trivial. Bostic, 939 S.W.3d at 351 (recognizing “that a defendant’s trivial

contribution to multiple causes will not result in liability”).

In an effort to rule out other applications of clopyralid-containing

herbicides as alternative causes, Carrillo and Halfmann observed that

Helena’s application in early July 2015 was the only application large

enough to cause the heavy losses alleged by the plaintiffs. This idea—

that only Helena’s large application of Sendero on a windy day could

account for the widespread losses alleged—appears throughout the

plaintiffs’ evidence and argument. But this approach largely assumes

the matter to be proved. If we assume that all the reduced crop yields

claimed in all the plaintiffs’ scattered fields had one source, then

Helena’s application of Sendero in July 2015 is perhaps a likely culprit

(although weather remains a possibility, and the plaintiffs’ experts

made no attempt to account for it). The law does not permit this

assumption, however.

Instead, the law acknowledges the reality that an injury may

have many plausible sources, and it puts the burden on plaintiffs to

proffer evidence accounting for plausible alternative causes other than

the defendant’s conduct. When an injury may have multiple

contributing causes, the plaintiff must at least show that the defendant’s

conduct was a substantial factor in causing the injury, taking into

account any plausible alternative causes raised by the evidence. Bostic,

439 S.W.3d at 350–51; Transcon. Ins. Co., 330 S.W.3d at 218. Here, the

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plaintiffs’ experts failed altogether to account for the potential

contribution of plausible alternative causes—such as other herbicides or

weather—to the plaintiffs’ reduced crop yields.13

The plaintiffs cannot account for plausible alternative causes of

reduced cotton harvests in the fall and winter merely by demonstrating

crop damage in July.14 There must instead be an affirmative showing

13 Carrillo acknowledged that expert testimony in this case would need

to exclude “other sources for the possible damage that the plaintiffs are

alleging in this case” but that he did not do so. Rosenfeld testified that he did

not know whether other applications of herbicides containing clopyralid could

have been responsible for the damage to the plaintiffs’ crops. Halfmann

testified that he had not personally excluded other causes but that he relied on

TDA inspector Pence in that regard. None of the plaintiffs’ experts conducted

an independent study or systematic review of other applications of herbicides

during the relevant time period that might account for the plaintiffs’ reduced

harvest. Instead, they relied on Pence’s TDA report. In this regard, Pence’s

report cannot fairly be characterized as scientifically reliable evidence. Pence

testified that his investigation indicated a possibility, as opposed to a

probability, of crop damage in Mitchell County that could be tied to Helena’s

application of Sendero. The only effort he made to eliminate other sources of

the crop damage, over an area comprising hundreds of square miles, was to

“drive up and down [four] roads looking for effects” from other applications and

to ask some of the farmers if they saw anything. He did not meet with all the

farmers or look into herbicide use by oil and gas operations in the area.

Moreover, he ignored a TDA computerized database known as the PIER

System, which tracks herbicide applications. Pence’s investigation cannot be

characterized as a scientific effort to account for other herbicide applications,

much less weather. Importantly, Pence made no attempt to determine the

cause of the plaintiffs’ reduced crop yields later in the year. To be fair, such

analysis was outside Pence’s job description. The burden was on the plaintiffs

and their attorneys to obtain expert testimony explaining the effect of the

alleged Sendero exposure in July 2015 on crop yields several months later,

taking into account other plausible explanations for reduced yield, such as

weather or other herbicides.

14Again, the experts acknowledged that observed herbicide damage will

not necessarily result in reduced crop yield. See supra at 23–24.

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that the defendant’s conduct was a substantial factor in causing the

reduced crop yield at harvest time, notwithstanding plausible

alternative explanations. Any such proof is lacking here. Other than

the experts’ say-so, the record is silent regarding the extent of the causal

connection between the crop damage observed by Pence and the farmers

in July and the reduced crop yield several months later. This “analytical

gap” in the causal chain between the allegedly tortious conduct and the

damages suffered requires summary judgment for Helena. See Gharda,

464 S.W.3d at 349; Ramirez, 159 S.W.3d at 912; Gammill, 972 S.W.2d

at 727.

III.

For these reasons, the evidence of causation offered by the

plaintiffs fails to raise the genuine issue of material fact necessary to

survive summary judgment. The court of appeals’ judgment is affirmed

in part and reversed in part, and a take-nothing judgment on all claims

is rendered.

James D. Blacklock

Justice

OPINION DELIVERED: March 3, 2023

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