CROP STIMULANTS AND PROTECTIVE AGENTS 537 



yield 40 to 60 bushels per acre has been very severely injured by 

 the colaspis root worm, while no apparent damage was done on 

 adjoining well-fertilized plots which produced 80 to 100 bushels 

 per acre, although the insects were found in both parts of the field. 

 In any or all of these ways small applications of fertilizers or stimu- 

 lants may produce results in crop yields far beyond the direct 

 nutrient value of the plant food applied. 



The practice is somewhat common in places of coating seed 

 corn by stirring with a paddle dipped in warm tar, and to some 

 extent castor oil has been used for the same purpose, the appli- 

 cation being made two or three weeks before planting so that the 

 oil coating may have time to " dry on." Turpentine has also been 

 used, and some have advised putting powdered sulfur with the 

 seed in the planter boxes. These of course are solely protective 

 agents, if they have any value. Their use is based upon experi- 

 ence, however, and not upon experiment, and thus far the practice 

 seems to rest upon no better foundation than that of planting 

 potatoes " by the moon," or " witching " for water, an " art " 

 which fails to find water twice in the same place if the operator 

 is blindfolded. 



