4 
Bulletin 69 . 
It has been found that spores are unable to germinate in the 
presence of small amounts of copper, and advantage is taken of this 
fact when plants are sprayed with Bordeaux mixture. The copper 
in the mixture protects plants, hence the better the spraying is done 
the more complete is the protection. The fact that Bordeaux is not 
a cure should be borne in mind, and to be a successful preventive it 
must be applied before the spores are disseminated. 
Fungi that live in the soil and attack the roots of plants are not 
dependent on spores as a means of dissemination. The root-like 
organs, or hyphse, spread through the soil from plant to plant, or 
they may be distributed by the cultivator or other means. With 
root diseases the treatment is more complicated, since there is usually 
no way of telling that a plant is affected until it is past recovery. 
A systematic rotation of crops is often of help in keeping annual and 
biennial plants healthy, but with orchards little can be done after 
the trees are attacked. Good care in every respect will be a great 
aid in keeping the trees free from disease. 
Many of the fungi which produce disease in plants are invisible 
to the unaided eye, hence they are apt to be regarded as something 
mysterious and the effects are often ascribed to other causes. The 
action of climate, altitude, winter injury, alkali and water are often 
mistaken for the effects of attacks of fungi. For example, the potato 
failures in the vicinity of Fort Collins have long been thought to be 
due entirely (o peculiar conditions of soil and climate, notwith¬ 
standing the fact that the famous Greeley potato district lies only 
twenty miles east and in the same altitude. Experiments conducted 
at this station during the past year prove that the lack of success is 
due primarily to root diseases which thrive much better in our 
heavy soil than in the lighter and better drained soils in the potato 
district. The fact that we have occasional successes here is no doubt 
largely due to planting clean seed in soil that is free from disease, 
or the conditions are not suitable for the best development of the 
fungi during certain seasons. 
APPLE TREE ROOT ROT. 
The presence of an unusual amount of yellow foliage on fruit 
trees last spring attracted attention in various localities in Northern 
Colorado. It is a well known fact that too much water will produce 
yellow foliage, and this is the cause that is commonly thought to be 
accountable for this condition. As the leaves usually regain their 
normal color before the close of the season but little attention is 
given to the subject. An unusual amount of rain in the early sum¬ 
mer was probably the cause of this general appearance of yellow 
foliage, but many fruit growers have noticed that occasional trees 
are affected in this manner year after year and finally die without 
any apparent cause, while adjacent trees remain healthy. It is not 
