348 GENERAL SCIENCE 



Smuts. Many of us are familiar with the masses of 

 loose black or dark brown powder which are found on the 

 heads of oats. These black masses are composed of mil- 

 lions of minute spores of a fungus known as oats smut. 

 These spores are carried through the threshing process 

 with the chaff that is usually mixed with the grain. When 

 planted with the oats, they germinate and enter the 

 young oat plant, where they branch in various directions 

 with the growing tissues of the plant. When the plant 

 begins to " head," the smut fungus develops a mass of 

 small threads within the tiny blossom. These threads 

 soon develop the countless black spores that form the 

 characteristic powder of smut as we see it on oats. Oats 

 srnut may be prevented by soaking the seed in a dilute 

 solution of formaldehyde. Corn and onion smuts are 

 quite common on ground where the crops are not rotated, 

 but they are not usually very troublesome. 



Black knot is a fungous disease which affects plum and 

 cherry trees. In warm weather large numbers of the 

 spores are produced on these knots. These spores are 

 carried by the wind to other trees, where they are likely 

 to germinate and start the disease. 



All diseased branches and badly infected trees should 

 be cut down and burned. Spraying diseased parts with 

 fungicides will prevent the spread of the disease. (See 

 Appendix II.) 



Peach leaf curl is due to the growth of a parasitic 

 fungus which enters the leaf, causing it to become enlarged 

 and to curl. The injured leaves fall early in the summer. 

 Winter spraying with Bordeaux mixture or with lime- 

 sulphur will destroy the spores of this fungus. 



There are other fungous plant diseases which are pecul- 

 iar to small regions. As a usual thing they yield easily 



