14 BULLETIX 1043, U. S. DEPARTAIEXT OE AGRICULTURE. 
this connection should be mentioned the importance of reducing 
risks of loss by the careful selection for seed purposes of varieties 
of the different kinds of crops which mature within the space of 
the reasonably safe efrowincr season of a given locality. 
At Grand Rapids. Mich., for example, the average date of the 
last killing frost in the spring is May 11. while the average date 
of the first killing frost in the fall is about October 8. This gives 
an average growing season of 150 days for crops which are readily 
injured by frost. Weather Bureau records further indicate that 
five times in 20 years the date of the last killing frost in the spring 
had been 10 days or more later than the average, and, similarly, that 
four times in 20 years the date of the first killing frost in the fall 
had been 10 days or more earlier than the average date. The reason- 
ably safe growing season for crops subject to damage by frost in this 
locality, therefore, is a little less than 130 days, covering a period 
from the last week in May to the last week in September. By 
adjustment of his dates of planting, as well as by the selection of 
the varieties of grains planted with careful regard to local climatic 
conditions as revealed by data covering extended periods of time, 
the farmer, in effect, can insure himself against frequent losses from 
frost. To a certain extent, he can also adjust his plan of farming 
to minimize the losses from drought and other climatic dangers. 
Thus far we have considered only safeguards against forces which 
the farmer can not control and against which his only chance, with 
minor exceptions, is to adjust his business in such a way that the least 
possible danger will result from their adverse action. There are, 
however, many other causes of loss which can be directly eliminated 
or at least partially removed. 
Loss from failure of seed to germinate can be eliminated to a great 
-extent by planting only tested seed. This is particularly true in the 
case of crops, such as corn, where the germinating quality is fre- 
quently injured, even when the yield is bountiful and the crop, to 
all outward appearances, is sound. Individual plant diseases, such 
as smut in wheat, oats, and barley, may be eliminated by a single 
treatment of the seed before planting. In sections where wheat scab 
occurs this evil may be largely controlled by a system of rotation in 
which wheat never directly follows corn, unless the corn is cut for 
fodder and all litter removed or thoroughly covered by plowing in 
the fall. The elimination of black rust by the removal of the com- 
mon barberry bush is a method of insuring against loss from this 
source. In the case of certain insect enemies, spraying or poisoning 
by one method or another may reduce or even eliminate their ravages. 
It is, of course, neither practical nor necessary to apply all preventive 
treatments at all times. The progressive farmer keeps himself 
informed as to the invasion of his region by any common disease or in- 
