4 o6 POPULAR SCIENCE MONTHLY. 



At the beginning of this period spraying was in no wise general. It 

 was of rare occurrence. Man suffered unresistingly the attacks of the 

 molds, mildews, rots and blights. The circulation of thousands of 

 state experiment station bulletins and similar bulletins from the na- 

 tional department of agriculture, the vigorous campaign of farmers' 

 institutes, farmers' reading circles, farmers' extension courses, and the 

 extended use of farmers' periodicals and agricultural papers have 

 served to bring the latest discoveries of science to the use of him who 

 will heed. As is to be expected, it is the man who most closely studies 

 his business, he who has most at stake, the large specialist in the cul- 

 ture of any crop, who first embraces the offered aid. The large 

 orchardist or vineyardist leads the way in the adoption of new methods 

 and new machinery. The revolution looking toward recognition of 

 the value of plant treatment is now so thoroughly inaugurated that the 

 treatment of such diseases, both insect and fungous, in the case of 

 fruit and trucking crops is of general occurrence. The movement, too, 

 is world-wide. 



The practical outcome of all the investigation and propaganda up 

 to the present time is that many hundreds of plant diseases have been 

 recognized; for a hundred or more have been prescribed remedial or 

 preventive measures, many of which are eminently successful; witness, 

 the treatment of cereal smuts, the peach curl, the grape black rot, the 

 powdery mildews. The saving occasioned by any one of these, as is 

 true of scores of others, would amply suffice to pay all the expense 

 of investigation and propaganda incurred in the development of the 

 whole field of plant pathology. By oat smut alone the estimated 

 damage in the United States yearly is $26,766,166, a loss avoidable by 

 an annual expenditure of less than four cents an acre. The saving 

 actually made in Dakota, Minnesota and Wisconsin in one year is 

 placed at $5,000,000. 



The future problems of plant pathology are manifold. The period 

 of growth must continue long before the work now undertaken is done. 

 Many diseases of even the cultivated plants are not yet recognized. 

 The diseases of wild plants, particularly the weeds, must too be studied 

 to ascertain the possibility of intercommunication of diseases between 

 weeds and crop plants. The life histories of all disease producing fungi 

 must be closely studied, particularly to determine their hibernating con- 

 dition. As yet the merest beginning has been made. The interrelation 

 of host and parasite must be studied, the periods, points and modes of 

 infection made known. The biology of the fungi, their life habits, con- 

 ditions of spore formation, characters of growth, relation to light, heat, 

 moisture, nutriment, etc.; their resistance to adverse conditions, their 

 longevity under various conditions of environment are all problems of 

 ultimate practicality. The question of species is unsettled and the 



