PLATE 89 
Early Ohio potato shoots showing characteristic sinus injury. With normal seed, 
injury of this type occurred only at a soil temperature of 21 0 C. and lower. The 
tubers, however, from which these shoots were grown had not passed completely 
through their dormant period. Due to the resulting slow growth and to the increased 
length of exposure of the bud to the fungus in the soil, injury occurred at a temperature 
of 24°. (See experiment 3, p. 468-470.) 
A. —Shoot showing the characteristic sinus injury and the accumulation of the 
mycelium of Corticium vagum in the sinus at the point of attack. 
B. —Three additional shoots of the same seed, showing more advanced and pro¬ 
gressive stages of the growing-point injury. 
