Helena Chemical Company v. Robert Cox ( 2023 )


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  •           Supreme Court of Texas
    ══════════
    No. 20-0881
    ══════════
    Helena Chemical Company,
    Petitioner,
    v.
    Robert Cox, et al.,
    Respondents
    ═══════════════════════════════════════
    On Petition for Review from the
    Court of Appeals for the Eleventh District of Texas
    ═══════════════════════════════════════
    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.
    2
    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,
    3
    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.
    5
    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
    6
    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
    7
    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
    8
    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.’”
    9
    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
    10
    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;
    11
    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.
    12
    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
    13
    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.”).
    14
    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
    15
    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.
    16
    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.
    17
    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”).
    18
    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.
    19
    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
    20
    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.
    21
    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.”).
    22
    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.
    23
    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,
    24
    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.
    25
    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
    26
    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.
    27
    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
    28