EXPERIMENT STATION BULLETINS. 



287 



APPLE-RUST {Gymnosporangium macropus, Lk.). 



This at times proves quite troublesome upon the foliage. It is believed 

 that one stage of this disease is passed in the so-called cedar apples of the 

 red cedar and that the orange-colored spores of that fungus can convey the 

 disease to the foliage of our apple-trees. As a preventive the red cedar trees 

 near apple orchards should be destroyed, if the disease is troublesome. 



Although there have been no experiments that prove the fungicides to 

 be effectual against this disease, it is not likely that the spores can gain 

 entrance if the leaves of our apple trees are kept well covered with Bor- 

 deaux mixture, as is desirable against the other diseases. < 



In addition to the above diseases the following are sometimes trouble- 

 some: 



Twig Blight {Bacillus amylovor^us, Burr.), which is similar to the 

 fire blight of the pear, but seldom spreads over the trees; Powdery Mil- 

 dew (Podosphcera oxycanthce (D. C.),De By.), which is most injurious to 

 seedlings in the nursery, but sometimes is troublesome upon orchard trees. 

 It is quite similar in structure to the powdery mildews of the cherry and 

 gooseberry, and the copper compounds will control it; Leae Spot (Phyl- 

 losticia pirina, Sacc.) is also given as injurious to the foliage, and Fruit 

 Spot {Phyllacliora pomigena (Schw.) Sacc), which has been noted in 

 some sections upon the fruit. 



INSECTS OF THE APPLE. 



BORERS IN THE TRUNK AND BRANCHES, 



There are quite a number of borers that burrow in the trunk and 

 branches of the apple tree. The more common are the Eound-headed 

 Borer (fig. 7) and the Flat-headed Borer (fig, 8). The former is said to 

 live three years in the wood as a grub and to bore in perfectly green wood. 

 Consequently each grub of this species is more destructive than those of 

 the flat headed borer, which are usually more numerous, but live only one year 

 in the tree as a borer and prefer sickly or newly planted trees for their attack 

 The imago of each borer deposits its eggs in June and early July, on, 

 the bark of the trees, usually in crevices or under rough, loose pieces, 

 near the ground, but sometimes on the smooth bark of the limbs. 



„ Fig. 7. — Flat-Headed Apple 



Tree Borer, Chrysobothris 

 Fig. 8.— Ronnd-headed Apple Tree Borer, Saperda Candida, a, larva ; b, femorata Fabr. o, larva ; b, 



pnpa; c, beetle. beetle. 



