184 STATE HORTICULTURAL SOCIETY 



FUNGOUS DISEASES OF THE APPLE AND PEAR. 



BY PROF. M. B. WAITE OF WASHINGTON, D. C. 



The lecture was given from a series of lautern slide pictures tbrow'n 

 upon a screen, illustrating the various points brought out. It is there- 

 fore not possible to reproduce it in printed form. The following paper 

 is an abstract intended to give the principal ideas that were presented: 



Pear and apple scab are w^ell known to be destructive to the pear and 

 apple in Michigan. The pear scab is caused by the fungus Fuslcladium 

 pyriniun and the apple scab is caused b}' Ftisicladiuiii (IcHtrliiciDn. They 

 are closely allied, and so nearly- the same in their general effects on the 

 host plant and in their treatment, that they may be considered together. 

 The fungus causes rusty, brown, and scabby sjtots on the fruit and pro- 

 duces a dull, rusty, sickly foliage. Infection b}' this fungus takes place 

 very early in the spring, commonly when the pears or apples arc^ in bud. 

 The disease is very susceptible to the effects of w^eather. Infection talvcs 

 place to a dangerous extent only during moist, rainy weather. Dry, 

 sunny weather is so unfavorable to the disease that if such weather con- 

 tinues through the budding and blooming period there will usually not 

 be enough scab to be W'Orth while sprajing for. The fungus spores live 

 through the winter on the fallen leaves and fruit, and possibly to some 

 extent on the twigs, and are ready to begin operations as soon as the 

 buds burst in the spring. The pear and apple blossoms, as you doubtless 

 well know% are borne in clusters of six to eight flowers, and each cluster is 

 contained in a single bud. 



As soon as the cluster buds open in the spring, exposing the individual 

 liow-er buds, the first spraying with Bordeaux mixture should be made. 

 When the flower buds have grown until they are just read}' to open, show- 

 ing the white or pink color of the flowers, the second treatment should be 

 made. The length of time between these two treatments will depend 

 upon the weather, but normally should be about a week. The second 

 spraying should be made barel}- in advance of the bloom. Occasionally 

 a blossom may be open during this second spraying. Nothing is to be 

 done while the trees are in blossom, but as soon as the bloom is shed a 

 third spraying should be given. Up to this time the treatment has been 

 mainly in the nature of an insurance of the crop. The spray is applied 

 ahead of the supposed infections. If the buds, blossoms, and young- 

 fruits are fairlv well coated with the fungicide, w'e mav be reasonablv 

 certain that the greater portion of them will escape unharmed, even if 

 a severe infection period should pass over. The most important work of 

 spraying for apple scab may be considered finished when the third treat- 

 ment has been made. For the third spraying it is very desirable to add 

 Paris green at the rate of one pound to 200 gallons of the mixture, and 

 spray for the codlin moth and leaf-eating insects at the same time. In 

 other words, Poideaux mixture^ may just as well carry an insecticide 

 along with it, so that the two substances are sprayed together. Any 

 further treatment should depend largely on the judgment of the grower. 



