Feb. 24,1923 
Early Vigor , Yield, and Rot Diseases of Maize 
619 
com suffered more from the combination of ear worm attack and weather 
conditions favorable to the development of ear rots. Both lots of corn 
were attacked approximately to the same extent by the earworms, but 
the com grown from moderately diseased seed proved to be much more 
susceptible to the attacks of fungi following earworm injury than 
com grown from nearly disease-free seed. Only 36.5 per cent of the 
ears from the moderately diseased seed were sound, while 61.1 per cent 
of the ears from the nearly disease-free seed were sound. Figure 16 
presents graphically the percentage of marketable com by weight pro¬ 
duced by the moderately diseased and nearly disease-free seed from the 
different dates of planting. 
A further analysis of the data, graphically presented in figure 17, 
shows that the increases in unmarketable corn in the later plantings from 
the moderately diseased seed were due to the increased number of rotted 
ears and not to any increase in number of chaffy ears. The decrease in the 
percentage of chaffy ears in the last three plantings from the moderately 
diseased seed is accounted for by the increased number of chaffy ears that 
were rotted. Ears and nubbins both rotted and chaffy were placed in the 
rotted class, since the rotting was considered more detrimental than the 
chaffiness. The decreased percentage of rotted ears in com grown from 
the nearly disease-free seed as compared with that grown from the mod¬ 
erately diseased seed is very significant and indicates that the corn grown 
from nearly disease-free seed possessed considerably more resistance to 
injury by the fungi causing ear rots, as well as more resistance to the 
root and stalk rots, when planted in infested soil. 
Additional data, similar to those in Tables XXI and XXII, are pre¬ 
presented in Table XXVI. A comparison of the field performance of 
the corn planted from the three different seed lots, varying considerably 
in percentage of infection, shows that the diseased seed is associated with 
reduced field stand, reduced percentage of vigorous plants, increased 
percentage of weak plants, and reduced total yield, as well as reduced 
yield of sound, marketable com. A considerable part of the increased 
yield of sound corn from the nearly disease-free seed is due to the smaller 
percentage of rotted ears. 
