EXERCISE XXVIII. 

 THE TREATMENT OF OATS FOR SMUT. 



Supplies for a Laboratory Section of Twelve. About twenty-four cubic centimeters of fo. malin (a 40% sorti- 

 tion of formaldehyde gas); three cylindrical graduates; 100 cc. burette containing about 24 cc. of formalin; twelve 

 500 cc. beakers; twelve pieces of blotting paper; twenty-four pie tins; two quarts of oats (smut present if pos- 

 sible) ; one yard of cheese cloth. 



INTRODUCTION. Oat smuts are parasitic plants, known as fungi, which grow in anfi 

 through the tissues of the oat plant. In mature form these fungi produce a mass of black, 

 powdery, dust-like spores which replace a part or all of the oat head. Oat smuts are repro- 

 duced from these spores in much the same way as other plants are reproduced from seeds. 

 When oats are threshed many of these spores cling to the grain. If the grain infected 



Fig. 56. 

 A sound oat panicle in contrast with oat panicles affected by smut. (Anderson.) 



with smut is planted the spore germinates and the resulting parasitic plant is in position to 

 penetrate the young seedling and grow up with the oat plant. When a fungus thus infects 

 a higher plant we usually speak of it as a disease. In order to control this disease of the 

 oat plant it is necessary to treat the seed grain in such a way as will destroy the smut spores 

 clinging to it, yet not seriously injure the grain. 



DIRECTIONS. Oat smut is very successfully treated with a solution of formalin — a 40% 

 solution of formaldehyde gas. The best solution strength for treating oats for smut is made 

 by adding one pound of formalin to SO gallons of water. This is about the same as 1 pjnt 

 of formalin to 400 pints of water, or 1 cubic centimeter of formalin to 400 cubic centimeters 

 of water. For the laboratory experiment about 400 cc. of the solution will be sufficient. 



9'. 



