Recent Apple Failures of Western New York. 63 



-growing on the upper surface, and at this date it has destroyed the 

 upper or epidermal cells, although it is probable that the mycelium 

 •of the fungus first spreads just under the cuticle, on top of the 

 layer of epidermal cells. Fig. 3 shows the fungus when it is better 

 established, and it will be seen that all the cells of the leaf are dis- 

 :arranged, the chlorophyll or green grains being few in number, and 

 the leaf has increased in thickness. This Fig. 3 is a cross section 

 through one of the blister-like elevations which are shown on the 

 Jeaf in Fig. 5. It will be seen that the fungus does not enter the 

 deeper tissues of the leaf, although it disorganizes them by its 

 parasitic effects. In Fig. 3, a spore can be seen at A, and two are 

 shown broken off their stems or hyphse, at B. In Fig. 2, the spores 

 can be seen in process of formation at the ends of the threads, and 

 at C one of the threads is cut off. The fungus itself is supposed to 

 pass the winter on young shoots, fallen leaves, and upon the fruit. 

 The spores form at a low temperature, and the early cold wet 

 weather of recent years has afforded excellent conditions for the 

 spread of the fungus. The apple scab is one of the so-called " im- 

 perfect fungi," — a name given to those fungi of which the perfect 

 form is unknown. The reader will recall that some fungi, like the 

 quince rust (see Bulletin 80), have two very unlike forms which 

 sometimes live upon different plants. There is every reason to 

 ■expect that the apple scab passes part of its existence in another 

 form ; and it is possible that the discovery of this other form may 

 give us a new means of combatting the disease. 



Yarious insects cause the occasional failure of the apple crop over 

 •considerable areas. One of the worst of these in western New 

 Tork is the bud-moth (see Bulletin 50). Another one, which was 

 serious in Wayne and Monroe counties last year, is the cigar-shaped 

 -case-bearer {Colcojphora Fletcherelld)^ an acccount of which may be 

 expected later on from the Entomological Division. The work of 

 this insect upon the foliage is shown on the next page. The plum 

 curculio has also been a serious pest upon apples in some places, 

 puncturing the apples and causing them to grow gnarly. Its marks 

 may be seen upon two of the young apples shown on the cover. The 

 apple-worm, the larva of the codlin moth, is too familiar to need 

 description, and is now pretty generally held in check by Paris 

 _green. The same remedy will also apply to the bud-moth and case- 



