96 MASSACHUSETTS HORTICULTURAL SOCIETY 



extending several inches above the soil. The MTiter has not 

 determined to what extent the root systems are commonly affected. 

 However, lesions have been observed near the tips of roots of four- 

 years-old plants, and of several plants examined unquestionably 

 the entire root system of each plant was affected. The union of 

 scion and stock, and the area immediately above, is the most 

 common point of attack. 



The first indication of the disease is a slight discoloration of the 

 bark. As the disease advances the color deepens to black and the 

 tissue appears water-soaked (plate 1, figs. 1,3). At first the lesions 

 are irregular in outline with a somewhat sharply defined margin. 

 Later as the affected area increases in size the blackened color of 

 the diseased area is blended more with the healthy tissue. The 

 lesions frequently encircle the stem. Soon cracks appear in the 

 bark extending in to the wood (plate 1, fig. 2). Later a swelling 

 of the stem as from girdling occurs at and above the affected area, 

 the cracks becoming deeper and more evident. In old lesions the 

 black, water-soaked appearance is lost. Sometimes the stem is 

 encircled by a shrunken area which contrasts sharply with the 

 swollen area immediately above. 



One very noticeable characteristic of this disease is the punky 

 consistency of the diseased tissue, especially that affected under- 

 ground. AVhen scraped, the bark, sapwood and frequently the 

 roots appear punky and lifeless, not uncommonly in areas where 

 no definite lesion is evident. 



Suckers developing from the roots of diseased plants are usually 

 spindling and yellow. They are commonly affected at the point 

 of attachment to the main stem, the tissue being blackened and of 

 a punky texture. 



Affected plants do not die quickly but linger on and yield in- 

 creasingly poor and few blossoms. It is practically impossible to 

 force such plants to increased activity by heavy applications of 

 fertilizers. The foliage of plants affected with this disease is fre- 

 quently of a lighter green color than that of healthy plants. Prob- 

 ably the number of plants actually killed within the duration of 

 time they are usually kept by growers is very small, but the normal 

 acti^dties of the plant are so materially interfered with that diseased 

 plants can be grown only at a financial loss. 



