194 MASS. EXPERIMENT STATION BULLETIN 170. 



(Lib.) Sacc), which attacks the twigs, has been known to cause great injury 

 to many poplars. Poplars are often affected by crown gall and various other 

 diseases. 



Oak {Quercus). — The oaks are affected bj- a number of diseases such as Septoria 

 dryina Cke., which produces a leaf spot, and by several mildews, e.g., Phyllactinia 

 suffjilta Reb., Asterina intricala E. & M. and Asterina patelloides E. & M., Micro- 

 sphtrra quercina (S.) Burr. The fungus Glirospnrium nerviseqmim (Fckl.) Sacc, 

 which also affects the sycamore, is sometimes found on oaks, affecting the leaf 

 petioles and veins, causing a browning, and, in severe cases, a loss of the foliage. 

 It is most common on the leaves of the shaded branches. Nectria cinnaharina 

 (Tode) Fr. also affects the oak. Oak "spangles," little saucer-shaped bodies on 

 the leaves which resemble the work of fungi, is caused l^y insects. 



Hickory (Carya). — Two or more leaf spots are found on the hickory, e.g., 

 MicTostroma juglandis Sacc. and Phyllcmticta caryce Pk. Some seasons hickory 

 leaves are quite badly spotted. 



Butternut (Juglans). — Butternuts are affected 

 by the following leaf spots: Ascochyta juglandis 

 Bolish, which is more or less common; Cercospora 

 juglandis K. & Sw., Glocosporiuni juglandis (Lib.) 

 Mont., Marssonia juglandis (Lib.) Sacc. The butter- 

 nut has suffered greatly from climatic conditions in 

 the past decade. 



Tunp Tree (Liriodendron) . — The leaves of the 

 tulip tree are sometimes badly spotted by insect work 

 which is often accompanied by fungi. 



Sweet Gum {Liquidambar) . — The sweet gum is 

 affected by a leaf spot {Septoria liquidambaris Cke. & 

 E.) and is susceptible to winter injury in the north. 



Magnolia. — The magnolia is affected by an 

 anthracnose (Colletotrichum spinaciw E. & H.) which 

 ruins the smaller branches and foliage of the tree. 

 Mildew {Asterina picea B. & C. and Asterina comata 

 B. & Rav.) is also found on the leaves. 

 Pine {Pinus) . — The white pine during the past ten years has been affected by 

 a root killing, which has been responsible for the burning of the leaf tips (sun 

 scorch). Various fungi, such as Septoria parasitica Hartig, and Hendersonia folii- 

 cola Berk., have been associated with this trouble, but both are apparently sapro- 

 phytes. The terminal twigs of the white pine are occasionally affected with Phoma 

 Harknessii Sacc, which causes the death of both the leaves and twigs. Scorias 

 spongiosa Schw. forms black incrustations on the leaves and twigs of the white 

 pine in the secretions of the woolly aphis. Rust {Coleosporium pini) sometimes 

 occurs on the leaves of the pitch pine. 



Catalpa. — The catalpa is affected with the leaf spots Phyllosticta catalpw E. & 

 M., Cercospora catalpw Wint., Macrosporium catalpa; E. & E., also with mildew 

 {Microsphmra elevata Burr, and Phyllactinia suffulta Reb.). A blight disease is 

 recorded which causes the leaves to turn black, shrivel and fall. This is said to be 

 caused by insect larva). Two wood-destroying fungi, e.g., Polyporus versicolor (L.) 

 Fr. and Polyporus (Poria) catalpw are found on the catalpa. 



Hackberry {Celtis). — The hackberry is occasionally planted as a shade tree, 

 and is affected by two mildews {U7icinula polychwta B. & C. and Sphwrotheca 

 phytoptophyla K. & S.) which are associated with a mite {Phytoptus) in producing 

 distortion of the leaves. Phleospora celtidis E. & M., Phyllosticta celtidis E. & K., 

 Ramularia celtidis E. & E. and Septoria gigaspora E. & E. are responsible for leaf 

 spots. 



Beech {Fagus). — A mildew {Microsphwra erineophila Cke.) is associated with 

 a mite {Phytoptus) on the leaves of the beech. The fungus {Scorias spongiosa 



Fig. 66. — Ar miliaria melted 

 on roots of maple. 



