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FUNGUS DISEASES OF THE APPLE. 



I. Attacking the Fruit and Leaves. 



1. The Apple Scab (Fiisicladiiim dendriticum, Venturia ponii). 

 This fung-us first appears on the leaves in smoky g-reenish patches, upon 

 which sooty pear-shaped summer spores are produced. Later it appears 

 on the fruit, where it develops under the cuticle or outer layer of the skin, 

 and forms dark brown, or blackish spots. It appears to thrive best in 

 cool, moist weather, and on closely crowded trees. The scab passes the 

 winter on infected fallen leaves, as black bodies imbedded in the leaf tis- 

 sues. 



Treatment. Plow under the dead leaves; spray with copper sul- 

 phate before the buds open, with Bordeaux soon after the leaves unfold 

 and every two weeks thereafter until the danger is over ; and prune so as 

 to prevent overcrowding and shading. 



2. The Ripe or Bitter Rot {Gloeosponum fructigenum, Glomer- 

 ella rufomaculans). This disease is very prevalent in Illinois and other 

 Central States. Brown spots appear on the half-grown apple, these 

 gradually enlarge and run together forming irregular patches. Black 

 points often arranged in concentric circles form on the diseased areas. 

 Spores ooze from the black points, and are carried to other apples by 

 wind and rain. The fungus winters over in another form in diseased ap- 

 ples, but a stage of the fungus winters over on cankered limbs, which 

 are the main sources of infection. 



Treatments. Thorough spraying with Bordeaux ; the destruction 

 of old diseased fruit ; the removal and burning of cankered limbs. 



3. The Black Rot [Sphceropsis malorum). This fungus produces 

 a characteristic disease. The early mature apples when affected first, be- 

 come brown, with black discolored spots under the skin, later become 

 black, and finally shrivelled, shrunken and wrinkled. The spores are 

 formed in the small pustules readily seen in the dried up fruit and in the 

 leaves. Paddock of Geneva has shown that this same fungus often pro- 

 duces cankers on the branches, which have open wounds made by sun- 

 scald, etc. 



Treatment. Spray with Bordeaux four or five times during the sea- 

 son at regular intervals, burn or plow under the diseased fruit and leaves, 

 scrape and coat with tar or paint the cankers on the larger limbs and cut 

 off and burn those on the smaller. 



4, Sooty or Fly-Speck Fungus {Leptothyrium pomi). This fungus 

 injures mature apples under moist conditions, either in low moist ground 

 or during a wet season. The popular names applied to this disease in- 

 dicate quite accurately the character of the spotting of the fruit. Such 

 varieties as Spy, Baldwin, and Greening are most susceptible to attack. 



Treatment. Spray at regular intervals with Bordeaux, and select a 

 high sunny position for orchard. 



