160 THE CULTIVATED EVERGREENS 



Segregation of the two types of liost for these fungi, when 

 it is possible, tends to hold the disease in check. While the 

 spores may be blown for distances 

 from a few feet up to several miles, 

 the removal of the pomaceous host 

 to within a distance of one mile will 

 reduce infection to a minimum. 



All diseased parts on either host 



should be carefully and consistently 



removed as soon as discovered. 



This will reduce the sources 



from which the infecting 



spores arise. 



Leaf-cast diseases. 



This name is applied 

 to a group of similar diseases 

 which occur on pine, larch, fir, 

 spruce and juniper and which are 

 caused by a number of fungi 

 belonging to the genera Lophoder- 

 mium, Hypoderma, and Hypoder- 

 mella. In general, the later symp- 



21. Cedar-apples on Jwwiperas toms resemble Very much those 



mrgimana. causcd by suu-scorch and winter- 



killing. Small yellow spots or bands first appear on the leaves 

 and these are followed by a browning of the entire needles. 

 In the spring, fruiting bodies of the fungi appear as black 

 lines or roundish dots along the middle of the dead leaves on 

 the lower side. These bodies contain the spores which are dis- 

 charged through elongated openings and which are blcwn 

 about by the wind to other trees. The leaf -cast diseases are 



