348 Missouri State Horticultural Society. 



will do well to trust to the ''say so" of those enabled to look a 

 little farther into the impenetrable mystery of creation. 



By those, then, who ask "if anything has ever been found out 

 as to the cause of grape rot," these facts may be accepted as ascer- 

 tained : The symptoms are caused by the decomposing power of 

 the growth of a low order of vegetation known as fungoid, and not 

 by "a bug." The generations of the pest are extended by spores 

 or germs similiar to the seed of other growth ; for instance, the 

 thistle. These germs are almost infinitely small and infinitely 

 multiplied. ' When ripe and ready for distribution they j)ervade 

 the atmosphere of an infected vineyard, and, being buoyant, float 

 wherever the air may bear them. They alight upon the surfaces 

 liable to infection and get inside — the Lord knows how. Warmth 

 and moisture are requisite to their germination and development. 

 Cold ( and perhaps other unknown influences ) checks their growth 

 when it has once begun, but in the dormant state their vitality is 

 unaffected by extremes of temperature or drought or moisture. 

 This is a characteristic of the vital principle of these low forms of 

 life — it seems too minute to be killed. The spore of the Phoma, 

 dormant, withstands a temperature of 30° below zero (Fahr.) and 

 130° above. It is proof against winter's cold and summer's 

 drought, being only liable to damage from these vicissitudes after 

 it has awakened into active life. Hence, when we find — as yearly 

 we may — these perithecia, filled with spores, upon the petioles, dry 

 leaves, and shriveled grapes under the trellis, we may be sure that 

 the prospect is encouraging, for another invasion of rot. Finally, 

 the only feasible means yet discovered to prevent the grape rot are 

 the destruction, or suppression of the infecting germ, or its ex- 

 clusion from contact under infectious conditions with the epidermis 

 of the fruit. These conditions are warmth and moisture. The 

 berry may be covered with infecting germs, but if its surface re- 

 main dry, or be quickly dried after wetting, these germs will not 

 sprout and take root there any more than will grow grains of wheat 

 scattered on the surface of a dusty road. 



But though finding these spores existent as stated is an indica- 

 tion that rot may appear in the future, it is not certain that a crop 

 of rotten grapes is to be always followed by a crop of spores. 

 Eestrained by various influences, the fungus may fail to develop 

 and mature its seeds. Then the initiative of a future crop is 

 lacking, just as we occasionally see a failure of seed corn ; we plant 

 the grain, but it won't sprout. 



