Parasitic and Saprophytic Fungi in Orchards. 191 



In 1898 Alwood* found that Sphaeropsis malorumPk. was 

 very cotr.ir.only associated with Phyllosticta pirina on leaf-spots. 



The parasitism of Phyllosticta pirina and P. limitata was 

 questioned in 1902 by Stewart and Eustace. f They said that 

 the fungi live saprophytically on leaves injured by spray or on 

 unspraved trees on leaves injured by atmospheric conditions. 

 Thev cite as an instance that when the sun comes out brightly 

 after a shower, the drops of water act as lenses and overheat the 

 tissue. It would, however, seem quite probable that the heat 

 of the sun would evaporate the water before any injury had 

 resulted and that the water would have a cooling rather than 

 heating influence, in that the heat would be used in the fonna- 

 tion of vapor. 



In 1892 ClintonJ found Sphaeropsis malorum to be the cause 

 of leaf -spot in Illinois and in 1903** in Connecticut. He said 

 that this fungus produced larger, more irregular spots than 

 Phyllosticta. 



Phyllosticta pirina Sacc, because of its smoky spores, was 

 transferred to Coniothyrium pirina Sacc. by Sheldonff in 1907. 

 As a result of experiments in 1906 and 1907 in the Ozarks, 

 Scottit found that the leai-spotis causedhy Sphaeropsis malor^im 

 and that Coniothyrium pirina which is associated with it has ap- 

 parently nothing to do with the formation of the spots. 



The Phyllosticta which appeared in these cultures was not 

 sm.oky-spored, but belonged to the true genus, Phyllosticta. 

 It causes a leaf-spot of the apple. In this region Ben Davis and 

 Winesap are the most susceptible varieties. On the leaves, small, 

 circular, brownish areas are formed, and im.mersed in this dead 

 tissue the pycnidia are form.ed, always few in number. 



(6) Prevalence. — No one fact is more surprising about 

 Phyllosticta limitata than its persistent appearance in the trap 

 cultures. It is not at all to be expected that it would be viable 

 all through the year. Throughout December, January and March 

 it was always present in abundance. It never failed to appear 

 in the cultures, even during the coldest periods of the winter. 



♦Alwood: Proc. Am. Assoc. Adv. Science. 47:413. 1898. 



tStewart & Eustace: Bulletin N. Y. Agricultural Exp. Station. 220:225-233. 1902. 



JClinton: Bulletin 111. Agricultural Exp. Station. 69:192-193. 1902. 



♦ ♦Clinton: Annual Report Conn. Agri. Station. 29S. 1903. 



ttSheldon: Torreya. 7:142-143. July, 1907. 



iJScott: Bulletin U. S. Dept. of Agriculture, Bureau of Plant Industry. 121:(3). 1908. 



