ASH DISEASES 95 



Control. 



The disease will probably not be noticed until the cluster- 

 cups have broken open and shed their spores. It would then 

 be of no avail to destroy the diseased parts of the ash, since 

 the spores have already been distributed. If practicable, ash 

 trees should not be grown in' the vicinity of marshy land where 

 the Spartina grass-hosts grow. In the absence of the grass- 

 host, so far as the life history of this rust is known, there is 

 no chance of infection of the ash. 



White Heartwood-Rot 



Caused by Fames fraxinophilus Peck 



White ash is commonly affected by this heartwood-rot in 

 parts of Iowa, Missouri, Kansas and Oklahoma, on the wes- 

 tern limit df growth of this species. The disease is rarely 

 found in eastern United States. West of the Mississippi 

 River, where the white ash attains only three-fom-ths its normal 

 size, ninety per cent of the trees are often found diseased ; a 

 fact which suggests some correlation between the condition of 

 the trees in this region and their apparent greater susceptibility. 

 The slow rate at which wounds heal, however, may be the 

 predisposing factor which accounts for the greater abundance 

 of the disease. Trees of all ages and especially those over 

 seven inches in diameter are affected. 



SymptorrtiS. 



The rotted area as seen in cross-section of the trunk is very 

 irregular in outline and often is more extensive on one side of 

 the tree. The normal wood of the white ash is light yellow. 

 In the first stages of decay, the wood is stained brownish. Later 

 the affected wood becomes whitish and is surrounded by a 

 brown zone where the decay is extending into the normal 

 wood. The spring-wood of each annual ring becomes 



