80 
Colorado P^xrerimext Station 
these diseases are eoiistantly spreading to new areas and gradually 
increasing their range. 
Within the past eighteen months three new and serious plant 
diseases have been brought into this country from abroad ; namely, 
the Black Wart of Potato, Flag Smut of Wheat, and Take-All of 
Wheat, Oats, Barley, and Rye. The White Pine Blister Rust, which 
has destroyed the White Pine forests of the Eastern States, was 
brought into this country from abroad. The same is true of the 
Chestnut Bark Disease which has caused enormous losses in the 
New England and Middle Atlantic States. 
Even in the United States many of our worst diseases occur only 
in certain sections. Many of the most serious plant diseases have 
not yet made their appearance in Colorado. There are, however, 
more diseases in the state at the present time than there were ten, 
fifteen, or twenty years ago and new ones can be expected to show 
up in the next few years. 
Federal and State quarantines are important means of exclud- 
ing injurious plant diseases. All nursery stock, seeds and bulbs, 
that are liable to be infested with injurious parasites are carefully 
inspected by the government inspectors and if found infested are 
destroyed. Quarantines are, however, not always effective and every 
now and then a disease makes its appearance in a new section of the 
country. For this reason every grower should be on the constant 
look out for the first appearance of a disease in a new area. -The 
early discovery and immediate suppression of a disease that has just 
been introduced may mean the saving of thousands of dollars to a 
community. 
Diseases may be brought into a new locality or introduced into 
clean soil by planting of diseased seeds or seeds that carry the dis- 
ease on their surface. The planting of seed of unknown origin should 
be avoided. Any seed that is likely to carry spores of disease pro- 
ducing organisms should be disinfected before planting. 
Eradication 
Disease control by eradication measures consists of the complete 
destruction of a disease producing organism in a given area. Eradi- 
cation measures are most applicable when exclusion measures have 
failed and a new disease has been discovered before becoming wide- 
spread. Eradication methods are best carried out by the State or 
Government. The Federal and State Governments have united in 
an effort to eradicate Botalo Wart, Flag Smut of Wheat, and Take- 
