640 INSECTS AFFECTING VEGETATION 



plants that are not only practically disease resistant, but are also 

 ideal as regards regularity and symmetry of growth, length, and 

 strength of flower stems, and yield, size, substance, and quality of 

 flowers produced. (Div. Veg. Path, and Phys. B. 23.) 



Leaf Blight (Phyllosticta Violae and Cercospora Violae) are 

 sometimes prevalent, and with downy mildew of violet should yield 

 to spraying with fungicides. 



Nematodes. These are, on the other hand, not amenable to 

 spray treatment. The parasite in the case is the same as named un- 

 der cucumber nematodes, likewise its effects. Soil treatment will 

 also be effective in prevention here. 



Root-rot (Thielavia basicola). This has not been reported as 

 troublesome by greenhousemen in Ohio, but it is scarcely possible it 

 can be entirely lacking when the disease occurs upon tobacco and 

 catalpa in fields. The blackening and rotting of the roots, due to 

 the fungus, will impair the development of the plants and the flower 

 growth seriously. It does not seem possible that anything short of 

 sterilizing the soil and starting new plants will check the root-rot 

 where once established. 



VIRGINIA CREEPER. 



Leaf-Spot. The leaves of Virginia creeper are frequently curi- 

 ously spotted by a leaf-spot fungus (Phyllosticta labruscae) which 

 gives dying spots with colored border. This leaf-spot is also very 

 common upon the Japan creeper and is identical, according to recent 

 reports, with the leaf -spot of the grape ; indeed we have a large num- 

 ber of the well known diseases of the grape attacking the Virginia 

 creeper. These include anthracnose, which may be distinct, the 

 black-rot fungus, of which this Phyllosticta may be a stage and pos- 

 sibly others. This would be especially true in the vicinity of culti- 

 vated grape vines. (Ohio E. S. B. 214.) 



DISEASES OF FOREST TREES. 



ASH. 



Trunk Rots. The ash as a forest and shade tree is a vigorous 

 grower, but it is often marked by the attacks of timber decays where 

 these enter through wounds or by means of the bases of dead 

 branches. We have urgent need for more knowledge of these 

 wound parasites. 



Leaf-Spots and Rust. The foliage of the ash is attacked by rust 

 (Puccinia fraxinata) but in the present state of our knowledge we 

 are unable to apply effective remedies. This rust, as in the case of 

 other rusts, shows by the presence of its reddish or brown colored 

 spore masses. Of leaf-spot fungi there are a number which call for 

 careful study. 



BEECH. 



Anthracnose. The anthracnose fungus (Gloesporium Fagi) of 

 beech attacks the leaves, but is not so serious as many of the other 

 anthracnoses. 



Leaf Diseases. While the beech is not largely planted, it is 

 nevertheless a useful shade tree. The leaves are often attacked by 



