ii6 THE TREE BOOK 



Spears under hot, moist conditions. The fungus 

 spends the winter in the munamied apples of the 

 previous crop, and is one of the best reasons 

 why all refuse should be cleaned from under 

 the trees, and why cuUs should not be left to 

 wither on the twigs. The spores of bitter rot 

 fungi germinate readily in the dew and rain, 

 during the heat of July, August, and September, 

 sending out minute threads which work through 

 the skin of the apple and feed upon its flesh. 

 These threads branch out and grow rapidly, 

 producing the circular, brown sunken spots 

 which you have often noted on the apple. 

 Fruiting pustules bearing innumerable pink, 

 massy spores start up from the center of the 

 fungus circle. At first these masses are wet 

 and sticky and easily transferred from fruit to 

 fruit by the feet of insects. Drops of rain also 

 help in the distribution of fungus by striking the 

 diseased spots and splashing the spores to other 

 fruits. Thus millions of spores may spread 

 from one fungus circle; and so ruin the entire 

 crop of an orchard. 



Row the Government Helps. It has been es- 

 timated that more than 90% of the vast annual 

 loss to the farmers and fruit growers of Amer- 

 ica has been caused by insects and diseases in- 

 troduced from abroad during the past twenty 



