a disease of such potential as the northern 
corn leaf blight of corn. The risk is unneces- 
sary, as valuable time-tested resistance is now 
available. A switch to exclusive and widespread 
use of a resistance that in time could possibly 
prove to be of the vertical, or short-lived 
type, could result in the production of future 
hybrids with unstable resistance and super- 
susceptibility to new races. 
Experience indicates that we should treasure 
the older, polygenic, and probably horizontal 
resistance, since it has a record of stability 
over a period of years, and use the newer, 
more hazardous, monogenic resistance as a 
supplement to it. Such a combination might 
give both higher resistance and stability. Such 
a breeding program will be the more difficult, 
and for the near future the more costly way, 
but it will be much safer and ultimately may 
be much more practical, 
FUTURE DISEASE-RESISTANCE 
REQUIREMENTS 
The work to be required of disease- 
resistance breeders and pathologists looms 
large for the future. Ultimately food require- 
ments will demand all possible elimination of 
disease losses to the major food and feed 
crops. Such demand will likewise require high 
plant populations and the increased fertility 
needed to produce the necessary high yields. 
Already we see such diseases as powdery 
mildew of small grains causing increasingly 
frequent and heavier losses of major propor- 
tions as optimum nitrogen requirements are 
met and dense stands become necessary. Other 
foliage diseases, previously of little concern, 
such as Septoria tritici leaf blight of wheat, 
likewise become seriously destructive as cul- 
ture is intensified. 
Much knowledge is yet to be gained by 
appropriate research before we have the nec- 
essary understanding to breed for resistance 
to these enemies of the food crops as effectively 
as we must when world population presses 
ever more forcefully against the food supply. 
Stepped-up support for production research in 
agriculture must replace apathy from public 
and private agencies, which have tended to see 
only surpluses and little need for more effi- 
ciency in crop production. Research must be 
done to understand the more durable and often 
intricate, horizontal types of disease resistance 
and to test their utility. Such an increased 
attack on disease should not be long delayed. 
When the need becomes imminent, it will be 
too late to legislate for effective crash pro- 
grams to breed more efficient crop plants, 
unless the appropriate research and the training 
of scientifically competent and agriculturally 
sophisticated plant pathologists and breeders 
have not been neglected during a passing era 
of localized plenty. 

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Boswell, Victor R, Plant breeding and the vege- 
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