The Bulletin. 19 



Corn smut spores sprout on the moist surface of the ground, and 

 form a number of infection spores that are carried by the wind, and 

 may attack any tender above-ground part of the plant with which they 

 come in contact. In manure, or on heavily manured ground these 

 infection spores are formed in large numbers and for a long period. 

 Moisture favors infection greatly by giving a chance both for the 

 infection spores to be produced on the ground and for these to germi- 

 nate and enter the tender plant parts. Sweet corn is much more sus- 

 ceptible than field corn varieties. Rank growth of the stalks favors 

 infection both because of the delayed drying of the ground surface and 

 because of the succulent tissue. 



Control. — Control measures for these three classes of smuts depend 

 on the modes of infection. In oat smut and 3tinking smut of wheat 

 spores lodged on the surface of the seed are the source of danger. These 

 two smuts can be easily prevented by external disinfection of the seed 

 at any time before planting. Dipping in Milestone solution, one pound 

 to four gallons of water, is effective ; but it is apt to injure the germina- 

 tion of the seed, particularly of oats. A better disinfectant is formalde- 

 hyde. Dilute the full strength preparation of this (rated at 40 per cent, 

 and sometimes known as formalin) at the rate of one pint to forty 

 gallons of water. Sprinkle the seed pile, shoveling it over until every 

 one is thoroughly wet. Cover with cloths for two hours, and then 

 spread out so as to dry rapidly. Before treating wheat for stinking 

 smut dip the seed in water, stir thoroughly and skim off the smut balls. 

 Treated seed may be planted as soon as dry, or later. Store in disin- 

 fected bins. Once in three years is ordinarily often enough to use this 

 treatment when home-grown seed is planted. 



In the case of loose smut of wheat the seed infection is internal, and 

 can not be reached by external applications. Uninfected seed must be 

 planted to avoid the disease. Sometimes clean seed may be obtained 

 from unaffected fields. Frequently it will have to be grown in a special 

 seed plot away from other wheat fields. Such a plot must be watched 

 closely at heading time so that every smutted stool may be pulled up and 

 destroyed before the spores scatter. In this way clean seed for next 

 year's general planting can be had, and if the seed for the plot is selected 

 from superior plants, the strain of wheat can be improved at the same 

 time. There is a method of hot water treatment that destroys most of 

 the internal infection of loose smut of wheat, but the process injures 

 germination to some extent, is very slow, and requires unusual care. 

 The seed grain is soaked four to six hours in water at ordinary tem- 

 perature, and is then dipped for ten minutes in loose bags in lots of not 

 more than a peck in water held within a fraction of a degree of 129° 

 Fahrenheit. This method is useful for insuring safe seed for planting a. 



seed plot. 



Corn smut is not carried either on or in the seed, and no seed treat- 

 ment is effective. There is no direct means of control, but several! 

 things may reduce its prevalence. Avoid feeding smutted material to< 

 stock lest the manure become contaminated. Do not use manure too* 

 freely on land where corn smut prevails ; compost it well or apply it as: 

 far ahead of the corn crop as possible. Do not plant corn too close,, 

 especially on soils that hold moisture or produce rank growth. Culti- 



