128 THE PLUMS OF NEW YORK. 



pruni Fuckel), which causes prominent deformities of the fruit. These 

 give the disease the common name or less frequently " bladders " 

 and " curl." The fungus attacks the developing fruits at an early stage 

 of their growth and causes the production of a spongy mass in the fleshy 

 tissue which greatly enlarges and distorts the plum. The stone in a dis- 

 eased plum is but rudimentary or very often not at all developed. Less 

 prominently but quite as frequently, the leaves are attacked, showing 

 as they unfold more or less red or yellow with a very decided curling and 

 arching of the leaf -blade. The disease usually spreads from the leaves 

 to the shoots, the infected shoots with their rosettes of mal-formed leaves 

 giving the tree a most unsightly appearance. Prevention at present con- 

 sists of removing the diseased parts and spraying with bordeaux mixture 

 when the buds begin to swell. Munsoniana and Hortulana plums seem to 

 be most susceptible to this disease. Atkinson ' has described several 

 species of Exoascus on the different species of wild plums, some of which 

 are liable to be found on the cultivated varieties of the native plums. They 

 are all very similar to Exoascus pruni, differing chiefly, in the eyes of the 

 layman, in forming smaller pockets. Sturgis 2 records an attack of one of 

 the leaf-curl fungi, distinct from the plum-pockets fungus, on varieties 

 of Triflora in Connecticut, which seemed to him to be of scientific and 

 economic importance. 



The leaves of the different species of cultivated plums are attacked 

 by several fungi which produce diseased spots on the foliage, which for 

 most part drop out, causing a shot -hole effect. These diseases pass under 

 such descriptive names as " shot -hole fungus," " leaf-spot,'* and " leaf- 

 blight." The fungus probably responsible for most of this trouble is best 

 known as the shot -hole fungus 3 (Cylindrosporium padi Karsten). The 

 Domestica and Triflora varieties are very susceptible to this fungus, which, 

 on the foliage of the first, causes spots for most part, while on the latter 

 the spots on the leaves are nearly always followed by holes. Varieties of 

 the native species, especially those of Americana and Nigra, are relatively 

 free from this disease. Another of these shot-hole fungi is Cercospora 

 circumscissa Saccardo 4 much less common than the former, but still to be 

 considered and especially on the foliage of Americana. All of these dis- 



1 Ibid. 



1 Sturgis, W. C. A Leaf Curl of the Plum Conn. Sta. Rpt. 19:183, PI. 2. 1895. 

 3 Arthur, J. C. Plum Leaf Fungus N. Y. Sta. An. Rpt. 5:276-281, Pis. 6-10. 1887. 

 ' Duggar, B. M. Fungous Diseases of Plants 314, figs. 147, 148. 1909. Pierce, N. B. A Disease 

 of Almond Trees Jour. Myc. 7:66-67, Pis. 11-14. 1892. 



