286 



THE PEANUT— THE UNPREDICTABLE LEGUME 



nite yellowing. With this yellowing a mycelial mat is usually found be- 

 tween the cotyledons but sometimes this mat is found before discoloration 

 of the cotyledons is evident. As the disease progresses, the mycelial mat 

 and cotyledons become darker and eventually the entire seed becomes 

 black or dark purple. The decay may gradually become apparent from 

 the exterior of the seeds so that the seed coat becomes shriveled, its color 

 fades, the seed appears oily, and feels soft (48, 162). Even in this stage, 

 however, the seed appears normal to all but the most experienced ob- 

 servers. These symptoms are shown in figure 2. 



This semi-detectable stage is soon succeeded by a stage in which the 

 dark decomposition products are visible from the exterior. At this stage 



Courtesy Alabama Agricultural Experiment Station 



Figure 2. — Concealed damage in runner peanuts. Outside and inside views of healthy- 

 seed at left and damaged seed at the right. The damage on the seed at the ex- 

 treme right is no longer concealed. 



the damage is no longer concealed, but is visible (48, 162). After the 

 seed are completely decayed it is not possible to determine whether the 

 infection spread from between the cotyledons or developed inward from 

 the surface. The important factor is the period in concealed damage dur- 

 ing which seeds with partially decayed cotyledons appear to be perfectly 

 sound seeds. 



Seeds with concealed damage have a strong, rancid taste (162). 

 This is the primary danger since a few of these seed taint an entire pro- 

 duct. In processing peanuts these seed are difficult to avoid since bitter- 

 ness develops before external symptoms. In addition to rancidity there is 

 an increase in free fatty acids (162), 



