HARM DONE BY WEEDS 15 



the harm done to cultivated crops. A point to which 

 attention has not yet been directed is that of harvesting 

 weeds with corn, hay, and other crops. In such a case, 

 where weeds are very abundant, reaping or mowing the 

 crop is much more difficult and prolonged, while drying 

 or curing is also rendered troublesome. Much oppor- 

 tunity is thus offered for the spoiling of both grain 

 and straw by long exposure to the weather, to say 

 nothing of loss due to birds and animals. Where many 

 thistles abound hand tying of sheaves is extremely 

 difficult, while pitching, loading, stacking, and thrashing 

 are all rendered more troublesome and costly. 



Money Losses due to Weeds. That great losses are due 

 to the infestation of crops by weeds requires no proof, 

 yet the exact amount of financial loss due to their 

 presence among crops has rarely been ascertained. In 

 those few instances where careful observations have 

 been made, the extent of the pecuniary loss has been 

 proved to be greater than the farmer would anticipate. 

 Percival, in writing of some field observations, says : l 

 " In many cases the moderately-weeded areas carried 

 from 40 to 50 per cent more crop than those on which 

 the weeds were unchecked." Again, according to 

 Maier-Bode, 2 Wollny has placed the annual loss of crops 

 due to weeds in Bavaria at an average of 30 per cent. 

 Investigations conducted in Norway by E. Korsmo 3 

 show that the effect of weeds on the yield and money 

 value of crops is very serious. Hay, barley, and pota- 

 toes were each grown on duplicate plots of the same 

 size, one being clean and the other weed-infested. The 

 crops were carefully weighed and the yields calculated 

 per hectare. The results may be given thus in English 



1 Jour. Bd. Agric., March, 1904. 



2 Fr. Maier-Bode, Die Bekampfung der Acker- Unkrduter. 



3 Tidsskr. Norske Landbr. 10 (1903), Nos. 6, pp. 247-280; 7, pp. 295- 

 330. (Review by F. W. Woll in U.S. Expt. Sta. Record, 1903-4, p. 683.) 



