346 Report of the Horticulturist of the 



fruit one-sided, frequently causing it to crack open and rendering it 

 especially liable to decay. Some varieties, like the Fameuse and 

 Fall Pippin are particularly subject to this trouble ; others, such as 

 Maiden Blush, for example, are comparatively free from it. 



The scab is caused by a fungus which grows on the leaves as well 

 as on the fruit. Attacking, as it does, both leaves and fruit, in many 

 instances it undoubtedly causes a serious dropping of fruit that 

 otherwise might develop into perfect specimens. There is a drop- 

 ping of fruit soon after blossoming which is the result of the pro- 

 cess of discarding the superfious fruits in the clusters. This is a 

 natural occurrence with perfectly healthy trees, and should not be 

 confounded with the later dropping which may be caused by insect 

 or fungous attacks. 



The scab fungus may attack either the upper or under side of a 

 leaf. When in an active condition it appears in spots like a very 

 dark green velvety mould or spreads in irregular threads near the 

 veins or over the surface of the leaf causing it to become crumpled. 

 In connection with severe attacks the leaves turn yellow and fall in 

 great numbers, a result for which the scab fungus is no doubt largely, 

 though not always wholly, accountable. The fungus feeds on the 

 leaf or fruit, causing the portion that is attacked to die. Wlien the 

 infested leaves do not fall the dead parts may become dried, break 

 and fall awa_y leaving the leaves ragged. If the fruit is not attacked 

 too severely it will heal under the dead skin leaving a russet brown 

 scar after the dead skin falls away. 



This somewhat lengthy description has been given that the reader 

 may know just what disease is called "apple scab" and something of 

 the nature of the injury it inflicts on apple foliage and fruit. 



Remedy. — As explained quite fully in Bulletin 84 of this Station, 

 it has been determined that three treatments with Bordeaux mix- 

 ture, 1 to 11 formula, will control this disease even in a very 

 unfavorable season. The manner of preparing the Bordeaux mix- 

 ture is given in article 4 on Fungicides and Insecticides. The 

 treatments should be made as follows : 



1. After the buds break but before the blossoms open. 



2. As soon as the blossoms have fallen. 



3. From ten to fourteen days after the second treatment. 



Paris green or London purple may be used with the Bordeaux 

 mixture in fighting injurious insects, as stated hereafter. The trees 



