55 



fled in so believing, that we shall develop eventually a corn that will be 

 practically resistant to these different diseases. 



This shows another view of the ears of these two most promising homo- 

 zygous strains and their first generation cross. When we consider the fact 

 that practically ninety-five per cent of the plants produce ears like that 

 (indicating) with three plants per hill, you can readily see where the 110- 

 115 bushels come from. 



PRESIDENT MANN: Is that field weight or dry weight? 



Prof. HOLBERT: Field weight would put it up to about 125. 



Q. What do you call that corn? 



Prof. HOLBERT: We haven't named it yet. 



Q. Do you have to combine that corn every year? 



Prof. HOLBERT: The eventual solution probably will be the combin- 

 ing of eight good homozygous strains into a recreated, and greatly improved 

 variety. Perhaps in ten years from now the terms that I have been using 

 today will be very familiar to you, and some of the methods which I have 

 described in the last few slides shall have been adopted generally. It looks 

 as though that was "the only way out" eventually. We have only begun the 

 permanent improvement of the great corn crop; we have just nibbled on the 

 surface of the matter of corn breeding, but we have nibbled enough to know 

 that we can get somewhere if we follow the right road. 



PRESIDENT MANN: Do the nibbling while the nibbling is good. 



Prof. HOLBERT: Yes, sir. In the meanwhile the data which we have 

 obtained during the last five years has fully justified us in a few very defi- 

 nite recommendations; one of which is the profitableness of field selection 

 of well matured ears from stalks that are healthy and ripening normally. 

 That is, we want to avoid selecting such prematurely dead ears (indicating) 

 from stalks that have dried up on account of a rotted condition of the roots 

 and stalk. During the last few years those two facts have been well estab- 

 lished. 



We know now that we not only have to consider the matter of infection 

 and freedom from infection out also the matter of resistance and suscepti- 

 bility. In other words disease-free seed may be very susceptible. Disease- 

 free seed of a very susceptible selection or variety may just be as unsatis- 

 factory from the standpoint of production as diseased seed of a less sus- 

 ceptible variety. 



PRESIDENT MANN: That is unless it is badly diseased. 



Prof. HOLBERT: Yes, unless it is very badly diseased. That empha- 

 sizes two very important things. One is a good field selection and the other 

 is the point which Mr. Mosher has mentioned, that is the selection of a type 

 which we have found to be associated more or less with resistance. The 

 selection of the type is next followed by the third point which Mr. Mosher 

 mentioned, namely the germination of the seed corn. I will not dwell on 

 this point for it has been emphasized previously. But I do want to empha- 

 size it again so that you may know we still believe in it and practice it. 



Here is shown some samples from the germinator. This is a disease-free 

 seedling (indicating). You will note the vigorous root development and the 

 clean, healthy condition of the interior of the "embryo portion." On the 

 opposite side of the screen is a diseased seedling (indicating the rotted con- 

 dition of the seedling). That may or may not indicate infection, but as far 

 as we know it practically always indicates susceptibility. 



Another very important factor to consider in the reading of the germin- 

 ator is the matter of vigor. There are two seedlings, both of which are dis- 

 ease-free. However, one is vigorous while the other is badly lacking in this 

 respect. Many times the difference in yield between the corn grown from 

 these two types of seedlings would average from thirty to fifty percent. This 

 (pointing to the vigorous one) is the type towards which we must select. 



During the last six years we have been using these three recommenda- 

 tions; namely, FIELD SELECTION. PHYSICAL SELECTION, and GERM- 



