534 



SCIENCE 



[N. S. Vol. XXXII. No. 825 



ods of cropping have deteriorated your 

 soil." The questions usually run, "What 

 has happened to the soil ? " " You have less- 

 ened the nitrogen." "You have changed 

 the humus condition," or "You have 

 withdrawn too much phosphates or pot- 

 ash," etc., as the case may be. The ques- 

 tion then arises, "What shall we do?" 

 The answer: "Rotate." "Raise stock." 

 "Plant corn." "Cultivate." "Clear 

 your fields from weeds." "Select seed." 

 Yet many able farmers who are doing all 

 these things reap 12| to 15 bushels of 

 shrivelled wheat where once they took 25 

 bushels to 30 bushels of 60- to 62-pound 

 stuff. Such men tend to lose faith in our 

 doctrine of conservation of the fertility of 

 the soil and our doctrines of the necessity 

 for crop rotation. Often the best rotation 

 gives the most shrivelled grain and then, 

 we as educators have been utterly at a loss 

 to explain the cause unless we could at- 

 tribute it to smut or rust, drought, rain, 

 sunscald, etc. Indeed there are many Red 

 River Valley farmers who will agree with 

 me that when climatic conditions and soil 

 conditions and harvesting conditions have 

 been most propitious for the development 

 of the wheat crop, often the yield has been 

 of the most inferior type of seed. Though 

 the bushels of grain and the tons of straw 

 may be somewhat larger, the quality is so 

 inferior as to be no longer in the class for 

 which the northwestern wheat regions were 

 once noted. 



I am glad, gentlemen of the congress, 

 that I am not only able to call your atten- 

 tion to these facts, which I think you rec- 

 ognize as not overdrawn, but that I can 

 name the causes so that any one of you 

 who wishes to investigate can verify. Our 

 older wheat soils are sick throughout or 

 sick in large areas in exactly the same 

 sense as certain cotton lands are sick with 

 root-rots, in the same sense as certain 



melon lands produce root-rot and blight, in 

 the same sense as old potato lands which 

 produce rot and scab, and in the same sense 

 as the Germans recognized, when they 

 spoke of flax being a bad crop to raise be- 

 cause it produced "Bodenmuedigkeit," 

 "flax-sick" conditions. I am now able to 

 recognize such wheat-sick areas and map 

 them as well as I could four or five years 

 ago for the flax-wilt disease. This map- 

 ping of the sick areas can be done any time 

 from the time the wheat plants first come 

 out of the ground to the time the stubble 

 is plowed in the fall. How many distinct 

 parasitic organisms it takes to make a 

 typical wheat-sick soil we can not yet af- 

 firm, but our experiments are sufficiently 

 extensive for us to state that at least five 

 such parasites are persistent internally in 

 most seed wheat, parasites which enter the 

 seed before it is mature and are carried 

 over to the next generation, and which are 

 also, when once introduced into the soil, 

 persistent there for a number of years fol- 

 lowing the introduction, and which, ac- 

 cording to variable weather conditions, 

 methods of handling the soil, variation in 

 the fertilization of the soil, etc., are able to 

 do a greater or less amount of damage. 

 They are so truly parasitic in structure 

 that they persist in their destructive work 

 in any type of soil and in any type of at- 

 mospheric conditions in which the wheat 

 plant can really survive. They are so 

 saprophytic in habits that they fn;it freely 

 on decaying roots and stubble, and thus 

 are readily distributed from crop to crop 

 and from field to field. They are so para- 

 sitic that through their connection with the 

 seed their distribution is made easy from 

 field to field and from country to country, 

 and I have found few samples of durum 

 wheat and few samples of hard wheats or 

 soft wheats, ^vinter wheats, ryes or barleys 

 that one or all of these wheat-destroying 



