Respondent Gary Bean, a farmer residing near Filer, Idaho, has for a number of years in his farming operations raised onion seed. He instituted this action as plaintiff, alleging in his amended complaint a breach of warranty of a chemical compound applied to 4.8 acres of onions, causing him $3,100.00 damages in loss of crops. Appellant Diamond Alkali Company, a corporation, manufactured the chemical, which appellant Twin Falls Feed & Ice, Inc., sold to Bean. The case was tried before a jury which returned a verdict in favor of Bean. The two corporate defendants appealed from the judgment entered following the verdict.
Briefly, the facts developed at the trial were that respondent Bean had discussed with an employee of Twin Falls Feed & Ice, Inc., the use of a pre-emergence chemical herbicide produced by Diamond Alkali Company. Bean decided that this herbicide should be used on a field which he was preparing to plant to onions for the purpose of producing a crop of seed. In 1965 an employee of Twin Falls Feed & Ice, Inc. applied the chemical to the field, which was then sown by Bean. A “very good stand” of onion plants emerged from the ground, but after a few weeks, portions of the plants discolored and later, within a month and a half, 85% of the plants died. Bean notified appellant Twin Falls Feed & Ice, Inc., but no action was taken regarding the damage. In 1966 Bean plowed up half of the onion field which sustained the greater damage and replanted it to a bean crop which he later harvested- and sold. He allowed the better half of the onion crop to mature.
The case was tried solely upon the theory of a breach of warranty, the controversy centering on the cause of the damage to respondent’s onions. The appellants denied that the herbicide was the cause and called two expert witnesses, each of whom testified that in his opinion the herbicide probably did not cause the damage. The respondent, on the other hand, contended that the herbicide did cause the damage, supporting his contention with the testimony of several farmers with long experience in the cultivation of onions, each of whom testified that in his opinion the damage was caused by the chemical herbicide applied to the land.
Respondent’s witness Robert Blass, whose property is located about two miles east of respondent’s property, testified that he had thirteen years experience as a farmer and ten years experience raising onions, including the type of onions involved in this action. He testified that during the same years involved here, he had raised onions on his own farm under soil and climatic conditions comparable to those prevailing on respondent’s farm, and that on a 7.7 acre field planted to onions, he used the herbicide in question on a large portion of it: He also left one strip in the field where no herbicide was used, and finally on the rest of the field he used another herbicide. He testified that about half of the plants died where the herbicide in question was used, but that in the rest of the field the plants matured normally. The witness was then asked whether he had an opinion as to what caused the damage, at which point *34the appellants objected on the ground that the question called for a conclusion of the witness and that he had not been shown to be qualified to answer. After further examination regarding the witness’s experience in raising onions, the trial court allowed the witness to answer. He testified that he did have an opinion as to the cause of the damage, stating that it was his opinion that it was caused by the chemical herbicide involved here.
Carl Blass, another witness called by the respondent, testified that he had been farming all of his life and had twenty years experience raising onions. He was familiar with onion diseases and had examined Bean’s field of onions. When asked if he had an opinion as to the cause of damage to the crop he testified, over appellants’ objections, that he had such an opinion and that it was his opinion that the chemical was the cause of the damage. Carl Blass also corroborated the testimony of Robert Blass regarding the so-called “experimental” field planted by Robert Blass.
The respondent also called as a witness a Mr. Whiteley who is employed as a field man by the Northrup King Company. He testified that he had worked on an experimental farm operated by the company which grows seed stock and that he was experienced in watching crops develop. He was familiar with Mr. Bean’s 1965 onion seed crop and when asked for his opinion as to the cause of damage he replied, over appellants’ objections, that in his opinion the cause of damage was “chemical probably.”
The respondent also testified in his own behalf that he had been farming all his life and had been operating his own farm for nineteen years. He had fifteen years experience raising onions and was experienced with their diseases and the vagaries involved in their cultivation. He too stated his opinion, over appellants’ objections, that the chemical herbicide caused the damage.
Both appellants strenuously objected to all of this opinion testimony on the ground that the respondent’s witnesses had no knowledge of plant pathology and were not qualified as experts to express an opinion. In each instance, however, objections were overruled, and appellants have assigned these rulings as error, contending that this opinion evidence was improperly admitted. The appellants also contend that there is insufficient evidence of a causal connection between the herbicide and the damage to sustain the jury’s verdict.
Examination of the record before the trial court reflects that if the testimony of the respondent and his witnesses, each of whom testified that in his opinion the chemical herbicide caused the damage to the crop, was properly admitted, then there is substantial and competent, although conflicting, evidence which was submitted to the jury and this court will not disturb the verdict. Skaggs Drug Centers Inc., v. City of Idaho Falls, 90 Idaho 1, 407 P.2d 695 (1965); Byington v. Clover Club Potato & Produce Co., 91 Idaho 165, 418 P.2d 206 (1966). The focal point of this appeal, therefore, is whether the opinion testimony of the respondent’s witnesses was properly admitted over the appellants’ objections that the witnesses were not qualified to express an opinion.
As a general rule a witness may testify only as to concrete facts, which are within the scope of his own observation, knowledge and recollection, as distinguished from his opinions, conclusions or inferences drawn from those facts. 31 Am.Jur.2d Expert and Opinion Evidence, § 2, p. 494; 2 Jones on Evidence, § 403, p. 750 (5th ed. 1958). There are, however, several exceptions to this rule, one of which relates to expert testimony. An expert is generally defined as someone possessing a certain skill or knowledge which is beyond the competence of the average layman or juror. Sturgis v. Garrett, 85 Idaho 364, 379 P.2d 658 (1963); Basye v. Hayes, 58 Idaho 569, 76 P.2d 435 (1938). In Greenstreet v. Greenstreet, 65 Idaho 36, 139 P.2d 239 (1943), this court, quoting from Ausmus v. People, 47 Colo. 167, 107 P. 204 (1909), defined an expert as
*35“ * * * one who has superior knowledge of a subject, and is therefore able to afford the tribunal having the matter under consideration a special assistance, and his knowledge may have been acquired by professional, scientific, or technical training or by practical experience in some field of human activity conferring on him an especial knowledge not shared by men in general.” 65 Idaho at 42, 139 P.2d at 242.1
A person possessing skill or knowledge qualifying him as an expert is generally allowed to express his opinion as to matters in issue when an opinion would be of appreciable help to the jury in finding the facts. 7 Wigmore on Evidence § 1923, p. 21 (3d ed. 1940); Greenstreet v. Greenstreet, supra; Grohusky v. Atlas Assurance Co., 195 Kan. 626, 408 P.2d 697 (Kan. 1965).
In the present case the witnesses called by the respondent were farmers with long experience in raising onions. Although none had formal education or training in plant pathology or herbicides, they were all familiar with the cultivation and harvest of onions and with the diseases to which onions are subject. It is settled that formal training or education is not essential to qualify a witness as an expert. Practical experience will suffice for such purpose. Greenstreet v. Greenstreet, supra; Grohusky v. Atlas Assurance Co., supra; 2 Jones on Evidence, § 413, p. 775 (5th ed. 1958).
In Associated Seed Growers, Inc. v. Johnson, 227 Ark. 235, 297 S.W.2d 934 (1957), which is quite similar to the case at bar, a farmer instituted a breach of warranty action against a seed producer, alleging that beans grown from seed sold by the defendant were afflicted with common bean mosaic. The defendant had warranted that the beans would be immune to this disease. In holding that certain farmers were competent to testify that the unsalable condition of the beans was due to common bean mosaic, the court stated:
“Marshall Johnson, Harold Ballentine and Boyce Wofford qualified as experts, through many years of experience by producing and dealing in beans, testified that in their opinion the beans were unsalable because they were afflicted with common bean mosaic. Appellant questions the qualifications of the witnesses to testify as experts. True, they were not trained pathologists, but they had long years of experience with beans, and a witness may qualify as an expert by experience.” 297 S.W.2d at 935.
Similarly in Reid v. Brown, 56 N.M. 65, 240 P.2d 213 (1952), the court held that a cattle rancher, by virtue of long experience in raising cattle, was qualified as an expert to express his opinion that his cattle did not die of natural causes. See also the following cases in which witnesses by reason of occupational experience were allowed to express expert opinions on various issues: Basye v. Hayes, supra; Hobbs v. Union Pacific R.R. Co., 62 Idaho 58, 108 P.2d 841 (1940) ; Davis v. Nelson-Deppe Inc., 91 Idaho 463, 424 P.2d 733 (1967); Gold Kist Peanut Growers Ass’n v. Waldman, 377 P.2d 807 (Okl.1962). For additional cases see Annot. 49 A.L.R.2d 932 at pp. 961, 973.
Whether a witness is sufficiently qualified as an expert to state an opinion is a matter which is largely within the discretion of the trial court. After this determination is made and the opinion evidence is admitted, the weight of the evidence is a matter for the jury. Hobbs v. Union Pacific R.R. Co., supra; Smith v. Big Lost River Irrig. Dist., 83 Idaho 374, 364 P.2d 146 (1961); Davis v. Nelson-Deppe Inc., supra; Reid v. Brown, supra; Gold Kist Peanut Growers Ass’n v. Wald*36man, supra. In the case at bar the district court ruled that the respondent’s witnesses were qualified as experts. We are unable to say that this determination was an abuse of discretion. Additionally the district court carefully admonished the jury each time it overruled the appellants’ objection to opinion testimony and instructed the jury at the close of the case that the opinions would be admitted into evidence, but that jn weighing the evidence the jury should take.' into consideration the background and qualifications of the witnesses. It is our opinion that the trial court did not err in overruling the appellants’ objections to this evidence and submitting it to the jury for its consideration.
The appellants also contend that the district court erred in refusing to grant their respective motions to dismiss at the close of respondent’s case. The record reveals, however, that following these motions the appellants presented evidence in their own behalf and did not renew their motions at the close of the trial. This court has held on several occasions that when a party presents evidence after the denial of his motion to dismiss, he waives the right to assign the ruling as errpr. Smith v. Sharp, 85 Idaho 17, 375 P.2d 184 (1962); Eckman v. Jones, 85 Idaho 10, 375 P.2d 180 (1962); Barry v. Arrow Trans. Co., 83 Idaho 41, 358 P.2d 1041 (1960); Knauf v. Dover Lumber Co., 20 Idaho 773, 120 P. 157 (1911). Appellants’ assignment of error on this issue is therefore without merit.
The appellants also contend that the evidence is insufficient to establish a causal connection between the chemical herbicide and the damage to respondent’s onions and that the respondent has therefore failed to meet his burden of proof. This contention, however, is predicated upon the hypothesis that the opinion evidence introduced by the respondent is inadmissible. It is our opinion that this evidence is admissible. It is also our opinion that there is substantial, although conflicting, evidence to establish the causal connection and hence, to sustain the judgment.
Judgment affirmed. Costs to respondent.
SHEPARD and SPEAR, JJ., concur.. Webster's Third New International Dictionary (Philip Babcock Gove, ed. 1967) defines an expert as “one who has acquired special skill in or knowledge of a particular subject through professional training or practical experience * * * T>roadly. one having skill or knowledge not possessed by mankind in general * * See also Black’s Law Dictionary (rev. 4th ed. 1968).