128 Agricultural Experiment Station, Ithaca, N. Y. 



PAET III.— NOTES ON SPRAYING PLUMS 



In spraying our plum trees for the black knot, of which a report 

 has recently been published, * notes were taken regarding the action 

 of these applications in checking a fungous disease known as leaf 

 spot {Septoria cerasina), causing an appearance resembling that 

 ■ shown in Fig. 10, and the rotting of the fruit. Fig. 11, also caused by a 

 fungus {Mo7iilia fructigena). Several varieties received the appli- 

 cation, a list being given below, but one unsprayed tree was left in 

 each plot. 



More treatments were made than are required for the control of 

 these- diseases, but the dates of all applications are here given: 

 March 8, 13; April 20; May' 2, 30; June 28; July 16; August 1. 

 If any plum diseases are 'susceptible to treatment by the use of 

 fungicides these trees should have been free from them. 



The leaf-spot or " shot-hole" fungus of plums first appears during 

 early sunnner. It causes the formation upon the foliage of small, 

 dark-brown or purplich spots. Such portions soon fall from the 

 leaf, which then appears to have been riddled with shot. Those 

 which are most seriously affected turn yellow and fall to the ground. 

 In this way trees are ^erj often defoliated. 



This disease can easily be controlled by making the following 

 applications : 



First. About two weeks after the blossoms have fallen, apply 

 the Bordeaux mixture. 



Second. Repeat first in two or four weeks, depending upon the 

 season. 



Third. Repeat the first in two to four weeks after the second^ 

 if necessary. 



The fungus which causes the rotting of the fruit, also attacks the 

 smaller branches, particularly of plums and peach trees. It may 

 penetrate the fruit and even the blossoms early in the year, but it 

 generally is most serious when the plums are nearly full grown. 

 The fruit turns brown in the affected parts, and this color spreads 

 rapidly throughout the fleshy parts and the rotting of the fruit is 

 soon accomplished. Such fruits may remain upon the trees, often 

 fastened together where they come into contact with each other, 

 and they may still be seen the following spring, where they form 



'Cornell Ajjric. Exp. Sta. Bull. 81. 



