126 STREAK DISEASE 



disease entirely. At other times the growth continues 

 slowly, the disease keeping pace. It is believed that 

 this disease is contagious, and that the punctures made 

 by aphis may be responsible for the spread of the mosaic 

 disease. 



Fourth may be mentioned the Streak disease which, 

 however, has been much more heard of in England than in 

 America. The symptoms and appearances are veri- 

 similar to those of the anthracnose. Taubenhaus and 

 James F. Manns have arrived at the conclusion that the 

 origin of streak is bacterial, and the same bacteria can 

 affect the common Clover of the fields. Plants may be 

 perfectly healthy until they reach their flowering period 

 at a height of 3 ft. or more. Suddenly brownish or reddish 

 patches in streaks appear on the stems, not necessarily at 

 the base, but even at lateral growths. The result is a 

 crippling of the growth, a curling of the flower buds, and a 

 peculiar contorted appearance in the flowers when they 

 expand. In severe attacks the whole plant collapses and 

 has to be removed. It has been observed that this disease 

 comes into evidence after a sudden change downward in 

 the temperature, or in watering with very cold water which 

 is thought to chill the roots. Being of bacterial origin it 

 is suggested that so far as possible the stems ought to be 

 protected from spattering by mud. 



Mildew is, of course, another common fungus pest, 

 but is controllable by dusting the flowers with sulphur as 

 previously mentioned. 



The general treatment recommended for controlling 

 the foregoing bacterial diseases is that of sterilizing the 

 soil, a subject dealt with already on page 50. There is 

 also the formalin process of killing germs as they lie in the 

 soil. " This treatment consists first in spading the soil 



