A SECOND OHIO WEED MANUAL. 297 



3. Weeds that are "indicators," i. e. diagnostic of soil con- 

 ditions, are most cheaply controlled by removing the conditions. 

 Drain wet places to avoid sedges, apply lime or fertilizers to crowd 

 cut sorrel. Let the despised sweet clover show what is the matter 

 or what the special excellence in uncultivated land. 



4. Persistence in the destruction of weeds by simple methods 

 counts for much more than spasmodic effort, and oftentimes for 

 more than expensive processes. It would appear to some persons 

 a waste of time to spend two seasons in eradicating- a small patch of 

 Canada thistles, although but a little time is required at each cut- 

 ting; the chief element is thoughtfulness. The same persons would 

 spend more time at once in efforts to dig them up completely, only 

 to find when the time has been spent, that the weeds, whatever 

 their name, have been spread by the process. 



Some weeds may be eradicated while others may only be subju- 

 gated. Canada thistle is often eradicated in a particular spot, while 

 f jr prickly lettuce this is a recurrent problem everywhere. The 

 latter can not now be eradicated, while it may be subdued. Other 

 examples may be cited in docks, white-top, chick-weed and purslane. 



SEED IMPURITIES AS A SOURCE OF WEEDS. 



Weed seeds are a frequent impurity in seeds of clover, alfalfa 

 and grasses, as well as in hay and seed grain. The many weeds 

 introduced in this manner give but a faint idea of the extent of these 

 impurities. New weeds are introduced and old ones are scattered 

 widely with the consequent damage to the purchaser. Seed oats 

 may contain impurities like charlock, or spreading mustard, and 

 prove a real damage when introduced upon a farm or in a com- 

 munity. In the case of seed grain the husbandman may choose to 

 rely upon his own judgment as to whether injurious impurities are 

 present, but he can certainly afford to "look sharp" at this seed 



rather than introduce 

 weed pests that will re- 

 main to plague him for 

 years to come. In the 

 matter of impurities of 

 clover seeds and alfalfa 



*IG. 1. Pocket Coddington and section of its lens, , 



natural^. the published work of 



The best lens for ordinary examinations. TT'11_ l ■ tvt -, / t> i 



The Doublet lens differs only in being cheaper, it is con- Hlllman m Nevada (Bill- 

 structed with a separate lens at each end of tube. letinS 38 and 47) and of 



this department of this Station in Bulletin 142, ought to be of some 

 aid to the purchaser. 



INevada and Other Weed Seeds, B. 38. (1897.) Clover Seeds and Their Impurities, B. 47, (1900.) 



