BROAD-LEAVED EVERGREENS 343 



In circular leaf -spot, small, more or less circular areas of 

 the leaves are killed and upon these the fruit bodies of the 

 fungus appear in concentric rings as tiny black dots. This 

 disease, caused by Cryptostictis species is common in some 

 regions on cultivated rhododendrons. Bordeaux mixture might 

 also be tried in the case of this disease. 



Shoe-string root-rot is caused by the fungus Ar miliaria 

 mellea. Fries, which has already been described in connection 

 with a similar disease of coniferous trees (see page 152). The 

 black strands of fungous material grow through the soil and 

 attack the roots, causing them to rot. This may result in the 

 death of the shrubs. Sooner or later the typical fruiting bodies 

 (toadstools) appear above the surface of the ground in the 

 neighborhood of the roots. The disease has also been found 

 upon azaleas. 



As soon as this disease becomes evident in a shrubbery, 

 the safest measures would be to sacrifice the affected plants. 

 These should be dug up and burned immediately, taking care 

 to remove as many of the roots as possible. A liberal amount of 

 quicklime should then be applied to the soil from which the 

 shrub was removed. No other shrub or tree should be planted 

 in this spot for about three years, during which period the 

 soil should be frequently turned over and exposed to the sun. 



In order to prevent the spread of the disease to other plants 

 in the shrubbery, a trench about two feet deep may be dug 

 around the diseased area just beyond the limits of the roots, 

 all soil removed being thrown inside the isolated zone. No 

 roots should be allowed to cross this trench. 



Diseases of kalmia. 



Leaf -blight occurs on the mountain laurel {Kalmia latifolia), 

 causing a blight or dry rot involving either large areas of the 



