164 



THE INDIA RUBBER WORLD 



[January 1, 1912. 



Some Views From Guayule Experts. 



THE PROPAGATION OF GUAYULE— A CRITICISM. 



IN an unsigned article in the November issue of The 

 India Rubber World', the question of the propagation of 

 guayule by means of cutting is discussed in the light of an 

 "interesting statement," made by Professor Mario Calvino, of 

 the Central Agricultural Station, San Jacinto, Mexico. The 

 writer of the article in question appears to have overlooked the 

 chapter in my book° w^here, under the caption "Vegetative Re- 

 production," the whole subject is discussed, and appears, also, 

 to be under the impression that my own attitude toward the 

 relative value of forestal operations, as compared with cultural 

 operations, is in favor of the latter as compared with the for- 

 mer. My statement is that the "ultimate and adequate solution 

 of the production of guayule shrub lies in the direction of cul- 

 tural rather than forestal operations." It is increasingly evi- 

 dent that, inasmuch as no measurable attention has been given 

 to forestal operations in Mexico or Te.xas, the methods of 

 forestal conservation can, in view of the much diminished sup- 

 ply, play but little part in the future production of the shrub. 

 As I have already said in these pages," the manufacturer 

 of guayule rubber has been thinking more of the immediate 

 financial return than of the conservation of the supply of guayule. 

 Abundant evidence may be seen in my treatise on the subject 

 to show that my attitude toward forestal operations indicates 

 their extreme value. It is, however, a fact that practically no 

 attention has been paid to them by owners of guayule lands. 

 Ultimately, therefore, we must, I believe, depend upon cultural 

 operations in the usual sense, and as applied to forestry, 

 since certain forestal operations might yet be made to yield 

 results. 



According to Professor Calvino, the propagation of guayule 

 by means of seeds has proved "more or less unsatisfactory in 

 practice." The experience of myself and of certain other stu- 

 dents of the subject goes to show that the difficulty of raising 

 seedlings is by no means as great as at first supposed. In the 

 hands of the plant physiologist, it has been shown that it is pos- 

 sible to germinate a very large percentage of the seed. The re- 

 sults attained at the San Jacinto station appear to be due to in- 

 sufficient study of the problem. In the article to which I refer, 

 it is pointed out that while Professor Calvino was working upon 

 the cultivation of the guayule from seed, Seiior Salvador Creci, 

 an agronomical chemist, announced that he had "succeeded in 

 propagating guayule by means of ligneous cuttings." The writer 

 goes on to say that "this idea was approved by Professor Cal- 

 vino, and thereupon measures were taken to effect the propa- 

 gation of guayule on this principle, seeing that in this way are 

 propagated the Anthemis and the Chrysantheiiiuiit, which are 

 of the same family as the guayule shrub, .\ccordingly, plants 

 were obtained, from which "ligneous, seed bearing and herb- 

 aceous cuttings were taken for planting in boxes in the open 

 air, and also in frames beneath glass. The herbaceous and seed 

 bearing cuttings germinated in ten days, and the ligneous ones 

 within fifteen days in the frame and twenty days in the open 

 air." Then follow details in regard to later treatment, to which 

 no reference need be made here. 



In the first place, there is but slight a priori reason for be- 

 lieving that, because some plant of a given family may be re- 

 produced by cuttings, others may also. This is purely a matter 

 for experimental evidence to decide. It is my purpose to point 



iVol. 45: pp. 70-71. November, 1911. 



* Guayule: a rubber plant of the Chihuahuan Desert. Publication 139 

 Carnegie Institution of Washington, pp. 193-198. 

 •India Rubber Worli>, vol. 41, pp. 115-118, January, 1910. 



out that the experimental evidence in the case, so far available, 

 is distinctly antagonistic to the impression given by the above 

 quotation. It is pertinent to point out, furthermore, that many 

 plants are known under culivation, which can either not at all, 

 or only with great difficulty and by special methods, be made 

 to strike root from cuttings, and these only from certain regions 

 of the plant. 



I have already shown' that it is possible to propagate guayule 

 by means of "ligneous" cuttings. I must, however, say that it 

 is not sufficient to use this adjective. It is possible to raise 

 plants of guayule from "ligneous" cuttings made (a) of the 

 root ; and (b) in such a manner as to involve the lower portion 

 of the stem just above the tap root; and (c) it is further possible 

 to make ligneous cuttings from new shoots which have been 

 forced to grow from the base only of the main stem by cutting 

 back close to the top of the tap root. I have, furthermore, shown 

 that stem tissue confined to the base of retoilos "Ml regenerate 

 roots, but beyond this, the evidence derived from a very careful 

 study of hundreds of cuttings, herbaceous and woody, both by 

 myself and by my former associate, Dr. J. E. Kirkwood, has af- 

 forded nothing but negative evidence. In view of my experi- 

 ments reported in the volume on guayule, it becomes the duty of 

 those who claim that cuttings may be made with ease from any 

 part of the plant (a claim which has been made in more than 

 one quarter), to furnish perfectly definite and unequivocal evi- 

 dence in support of their statements. This is made necessary by 

 the weight of the evidence to the contrary already in hand, and in 

 view of the danger that capitalists and their emulators may be 

 misled by accounts which furnish incomplete proof of the state- 

 ments made. I have in mind one instance of a Mexican gentle- 

 man, in the employ of one of the prominent guayule companies, 

 who clandestinely (with regard to myself) carried on an ex- 

 tensive experiment, as the result of which he made the asser- 

 tion that the guayule could be readily propagated by cuttings 

 without the loss of any rubber. It was, perhaps, a piece of good 

 fortune that I was able to make a personal examination of the 

 experiment grounds. Having seen the results for myself, I do 

 not hesitate to assert that not a single plant had been obtained 

 from a cutting of any kind. Perhaps I may cite one experience 

 by way of illustration of the question at issue. Doctor Kirkwood 

 made a large number of cuttings, quite independently of myself. 

 One of these started to grow, and in the course of a week or 

 so not only produced a number of leaves, but flowers as well. 

 As a result of a friendly challenge, the cutting was dug up and 

 examined in the presence of both of us. It turned out that the 

 basal portion of the cutting had, indeed, produced a root, but 

 a critical examination showed that this lower end was simply a 

 portion of the base of the main stem, just at the point at which 

 the tap root leaves it. As my expectation was thus confirmed, 

 it will be seen that there is here more than merely negative evi- 

 dence. I must furthermore point out, as I have already done 

 elsewhere, that under favorable conditions, not at all hard to 

 establish, guayule cuttings will, in a very large percentage of 

 cases, send out new leaves and appear to be growing. As a 

 matter of fact, however, the appearance is quite deceptive. 

 Although putting forth leaves and appearing vigorous, they are 

 not producing roots, and it takes no great experience to realize 

 that roots are quite as necessary as leaves, if a plant is to grow. 



In justice to Messrs. Calvino and Creci, it should be said that 

 by "ligneous cuttings," they may have meant those portions 

 above indicated. In the quotation, which I have had recourse 

 to, there is no direct evidence to the contrary. But until the 



1 In the book above cited, pp. 193-198. 



