292 State Horticultural Society. 



barometric pressure. When we take into consideration that 

 there is an atmospheric pressure of about fourteen pounds 

 to every square inch of surface, or twenty-eight pounds to 

 every square inch of leaf, and when we are also told that 

 men, climbing our highest mountains, bleed at nose, eyes and 

 ears caused by the lack of external pressure, what is more natural than 

 that during a very low atmospheric pressure there should be rupture of 

 cell structure in our tender plants, leaves or twigs, that the sap should 

 ooze out and be evaporated on the surface of the leaves and form a feed- 

 ing ground for the aphides, which with their system of propogation — 

 metagenesis and parthenogenesis multiply so rapidly, being an effect 

 and not the cause of honeydew and kindred phenomena such as blight. 

 What condition could be imagined more favorable to the development 

 of blight than a tender fruit twig or leaf, its cell structure ruptured by 

 the above named causes and conditions? A blight spore comes flying- 

 through the air, finds a lodgment in a microscopic crevice full of sap, 

 a perfect condition to grow in, gets its root system established and rap- 

 idly pushes its destructive growth along until the whole tree is ruined. 

 Three conditions may exist during these low barometric periods: 

 1st. Certain varieties of trees and plants may be able to stand the lack 

 of pressure without rupture. 2nd. They may be ruptured and there 

 be no blight spores, or Srd. They may be ruptured and a spore, or 

 hundreds of them, may find a suitable lodgment to start whole planta- 

 tions of mycellia and destroy the tree or plant. 



Now for the practical feature of this theory, if there is even a 

 mere possibility of its 'being true, it should be investigated, and with all 

 due respect, I submit it for the investigation of scientists, who, vnih. 

 infinitely better facilities and opportunities may demonstrate the truth 

 or falsity of it, and if true how much easier it will be to head off mucli 

 of the damage now sustained by fruit growers by immediately spraying 

 trees during low barometric periods before the spores find a permanent 

 foothold. 



