226 



THE AGKICULTURAL NEWS. 



JuLv 23, 1910. 



case, the sacrifice of a portion of the crop is not only 

 justified, but often absolutely necessary, in order to 

 prevent the loss of the whole. Remedial, followed by 

 preventive measures, or remedial measures alone, can 

 only be recommended in such a case, when the result of 

 long experience has proved conclusively that these 

 measures are adequate to prevent the spread of the 

 disease. 



The treatment of endemic disease is of a different 

 nature. In this casei there is often little risk of the 

 total loss of a crop, or even of the loss of so great 

 a part of it as takes' away all profit from the grower. 

 Most frequently, the main object is to reduce the 

 percentage of loss due to the disease to a minimum, 

 and thus to increase the profits to the maximum 

 obtainable in the conditions under consideration. Then 

 it is that remedial and preventive measures become of 

 the first importance. Total destruction can be but 

 rarely recommended, because it certainly involves the 

 loss of part of the crop, and possibly, that of part of 

 the capital expended on removing dead trees and on 

 replanting others which often give no return for five or 

 six years; moreover endemic diseases are apt to affect, 

 to a greater or smaller extent, almost every tree or 

 plant on any plantation where they occur. The posi- 

 tion of the mycologist in this case would appear to be 

 a very simple one. In reality this is not so. In recom- 

 mending remedial and preventive measures, he has 

 to consider if the expense involved will gain adequate 

 compensation in the additional profits derivable from 

 the treatment. If not, then all he can say is that 

 the existing state of things must be permitted to 

 continue, and in so doing, he allows the planter to run 

 the possible risk of the endemic disease becoming 

 epidemic, and causing the loss of all his plants. 



The conditions which determine if the expense 

 involved in remedial measures is justified by the 

 additional profits obtained are often governed by the 

 interaction of numerous, and somewhat delicate, factors. 

 Such are, for example, the general circumstances of 

 climate, the fertility of the soil, its suitability to the 

 crop grown, and the amount of co-operative effort to 

 reduce the disease that is likely to occur in the neigh- 

 bourhood under consideration. 



In recommending remedial measures, two other 

 important factors must be taken into account, namely, 

 the amount of capital available for carrying them out, 

 and, if carried out, their cumulative effect on the sup- 

 pression of the disease. Frequently, the execution of 

 the best remedial measures, in any given case, involves 



the outlay of a certain amount of capital, and where 

 this is not available, less effective, though frequently 

 much cheaper, measures must be recommended. Con- 

 sequently, it often happens that two or three alternative 

 sets of treatment have to be suggested, while the choice 

 of that set which is most applicable in any case, is left 

 to the person who is raising the crop. In some instances, 

 where there is little or no available capital, as in the 

 case of small holders, all that can be suggested by the 

 scientific adviser may be that the disease be permitted to 

 exact an annual toll, as long as this toll does not involve 

 all, or the greater portion, of the profits. On the other 

 hand, those possessed of spare capital should bear in 

 mind that the investment of it in thorough and reliable 

 treatment of their crops will often yield a larger 

 return of interest than the money could ever bring in if it 

 was inrested in ordinary securities, though the risk in- 

 volved is necessarily somewhat greater. Further, money 

 thus spent not only increases the yield in any given year, 

 but, if the treatment is continued, earns as it were 

 a higher rate of interest each year, until a steady maxi- 

 mum is reached, owing to the cumulative effect of the 

 treatment on the suppression of the disease, which sup- 

 pression continues until the loss due to the disease 

 reaches the minimum that can be effected by that 

 treatment under the given circumstances. Now, 

 it often happens that a grower desires to increase 

 his annual output of produce, and in order to do so 

 invests additional capital in new land; if, however, 

 he were to invest this capital in carefully carrying 

 out approved measures for reducing the diseases 

 of his crop, he would probably find that his yield 

 would increase to such an extent that the interest 

 on his capital when expended in this way was 

 greater than that which he would have obtained had 

 he invested his money in more land. 



It will probably be clear now, that it is not 

 always an easy matter for the scientific adviser to 

 make suggestions as to the best treatment for 

 any given disease. In addition to the technical diffi- 

 culties of his work, many considerations of a very 

 varied nature must also be taken into account, and 

 it is in dealing with these that the co-operation of the 

 practical agriculturist is of the greatest service. Fre- 

 quently, portions of the diseased material are submitted, 

 for examination by the pathologist, which are forwarded 

 almost without any word of explanation. No information 

 is given with regard to the field characters of the disease, 

 its extent, and the general conditions which may affect 

 it; and no hint is afforded as to the amount that 

 the planter is prepared to expend in controlling it. 

 When this is the case, the work of the mycologist is 



