68 Stevens — Science of Plant Pathology. [June 



fungicide has been found in the various sulphur washes. 

 There has been very remarkable growth in the perfection of 

 spraying appliances; pumps and dusters of many kinds are 

 upon the market. Particularly is the improvement in nozzles 

 to be noted. Nozzles constructed upon scientific principles, 

 capable of applying the liquid in the form of the finest spray 

 to the tops of the highest trees. In the place of the old hand 

 pump and pail we find barrel pumps on wheels, tanks on 

 wheels with pumps operated by gearing attached to the 

 wheels, and finally for the larger fruit farms and for munici- 

 pal care of shade trees are multiple pumps driven by steam 

 power. 



The treatment of seeds to kill adhering spores has been 

 improved upon in many details. It illustrates especially well 

 the nature of the development during the present epoch of 

 plant pathology. Originally the treatment for wheat smut 

 was based purely upon superstition. Pliny, for example, says 

 that 'if branches of laurel are fixed in the ground the disea % 

 will pass from the field into the leaves of the laurel.' Tull 

 in 1730 says that there are but two remedies proposed, brin- 

 ing and changing the seed. The avoidance of certain kinds 

 of manure because of their effect upon the host plant and 

 because they carried the smut spores was also advocated 

 about that time. The scientific demonstration by Brefeld 

 that the plant is susceptible only when very small, gave rise 

 to the thought that by hastening the early growth the period 

 of susceptibility could be shortened, and methods of planting 

 and tilling in accord with that idea were advocated. In addi- 

 tion to cultural methods mechanical treatment of seeds, such 

 as passing the wheat loosely between millstones, violent fan- 

 ning, etc., were suggested about 1786. The chemical treat- 

 ment of seeds, says Tull, was accidentally discovered about 

 1660 by the sinking of a shipload of wheat at Bristol, and 

 afterwards, finding it unfit for breadmaking, it was used for 

 seed wheat. The following harvest in England was very 

 smutty except in the case of this accidentally brined seed, 



