FUNGOUS DISEASES OF COLORADO 
CROP PLANTS 
By WILFRED W. ROBBINS and OTTO A. REINKING 
INTRODUCTION. 
Colorado crops, of orchard, garden and field, are not troubled 
with as many fungous diseases as are those of the states to the east 
and west which have a moister climate. Colorado’s comparative 
freedom from fungous troubles causes frequent comment from 
those who are familiar with conditions as they exist in the east. 
Such destructive diseases as bitter rot of apple, brown rot of stone 
fruits, peach leaf curl and late blight of potato do no injury to 
crops in Colorado. 
The direction of migration of economic plant diseases follows 
rather closely the direction of migration of man himself. Man is 
the chief agent in the spread of disease from one locality to an¬ 
other far distant. Prior to 1888, one finds little recorded mention 
of plant diseases within Colorado’s borders. And we have reason 
to believe that up to that year and even up to several years later, 
fungous diseases of cultivated plants in Colorado were largely un¬ 
known or not serious enough to attract much attention. Today 
many diseases have permanently invaded the state. This has been 
due to more intensive cultivation in the state, to an introduction of 
a greater variety of host crops, and (until a few years ago) to a 
lack of proper inspection laws. 
Crandall writes in 1891: ‘Tn all localities east of the moun¬ 
tains there is yet entire freedom from fungous diseases, with the 
exception of the occasional appearance of plum pockets on native 
wild varieties. The bacterial disease, variously known as ‘pear 
blight,’ ‘apple tree blight,’ ‘twig blight,’ is prevalent, and in some 
sections has done great damage. In the western districts diseases 
and insect troubles are at present unknown, but it can hardly be 
hoped that the immunity now enjoyed will continue. Growers in 
that district should prepare themselves to profit by the experience 
gained elsewhere and meet the first attacks with determined efforts 
at extermination.” This was in 1891. Some years later, in 1898, 
Crandall (Crandall, C. S.. nth Annual Report Colo. Exp. Sta. 
for 1898) reports as follows: “Colorado orchards have in past 
years been free from fungous diseases, but the diseases which have 
given the eastern growers trouble are gradually coming in and 
