26 AGRICULTURAL 



which vary with the variety. The conditions under which 

 ripening proceeds with the best results is an important field for 

 investigation. 



As is well known, apples, after they have ripened, are very 

 prone to rot or decay. This is doubtless nature's provision 

 for freeing the seeds from the inclosing fruit. How to control 

 this tendency to rapid decay is the most serious problem to be 

 solved in the handling of apples. As in all forms of decay, as 

 that term is ordinarily used, the rotting of apples is due to the 

 action of some of the lower forms of vegetable life. 



In our investigations we have not found bacteria acting as 

 the cause of decay, as is so frequently the case in other material, 

 and this is doubtless due to the acidity of apples, which is un- 

 favorable to their development. The destructive agent in the 

 case of the apple is one or more forms of the fungi. In our ex- 

 periments, which have been chiefly concerned with the Baldwin, 

 we have found two forms of rot common. In one the affected 

 apple shows a small brown spot upon the surface, which grad- 

 ually spreads until the whole apple is involved, the pulp remain- 

 ing tolerably firm. Later the surface becomes darker in color 

 and is seen to be studded with minute pimples or pustules. 

 These are the fruiting of the fungus which causes the rot, and 

 contain the spores by which it is propagated. Microscopic ex- 

 amination of the pulp shows it to be permeated by the thread- 

 like mycelium or vegetative part of the fungus. This form is 

 the so-called ^^brown rot." Another rot similar in appearance 

 to the foregoing, but producing darker spots and a bitter taste, 

 known as the bitter rot, which frequently affects apples, has 

 not been found at all abundant on the Baldwins in our experi- 

 ments. In the other common form the color of the rotting 

 area is much lighter than in the preceding forms, being light 

 or yellowish brown; the pulp becomes very soft. The fruiting 

 of the causing fungus occurs in white rounded tufts upon the 

 surface, the tufts taking on later a bluish green color, due to 

 the matured spores. This form of rot is produced by one of the 

 common mold fungi {Penicillium glaucum), so abundant on 

 various kinds of decaying matter. 



