50 Minnesota Plant Life, 



peated and thus smut is perpetuated from year to year. On 

 account of the habits of the smut it is a disease of grain which 

 can be eradicated by the intelligent farmer, if he will take the 

 trouble to kill all the smut-spores which are clinging to the hairy 

 ends of his seed-wheat kernels. This can be done by "blue- 

 stoning," or by immersing the seed-wheat for five minutes in wa- 

 ter of 132 degrees Fahrenheit. By such means the vitality of the 

 smut spores is destroyed, for they are exposed at the end of the 

 grain while the wheat plantlet itself inside the kernel is pro- 

 tected by the firm fruit-wall and is not injured by the poison or 

 by the heat. By such methods if generally and continuously 

 employed, it would be possible to terminate the enormous finan- 

 cial losses which farmers in Minnesota and the Northwest sus- 

 tain from the various cereal smuts. 



Rusts. Related to the smuts are a variety of plants which 

 may for convenience be grouped under the general name of 

 rusts. Of these a great many different kinds exist in Minne- 

 sota. They infest the leaves of numerous species of plants, the 

 Labrador tea, the pines, spruces, and tamaracks, the golden- 

 rods, asters, thistles, bellworts and poplars, the flax, willows, 

 horsemints and sunflowers, the junipers, pears, apples, beans, 

 violets and a great number of others. 



Wheat-rusts. The forms of greatest economic interest are 

 the three sorts of rusts which attack wheat. There are over 

 700 different kinds of rusts belonging to the wheat-rust type, 

 many of which occur on grasses, but the majority on numerous 

 other varieties of plants. The wheat-rusts are among the most 

 remarkable of fungi from the singular custom which they have 

 of changing periodically their habitation from wheat to other 

 plants. Not only do they change their place of abode, but they 

 change their form and structure as well, so that it would be im- 

 possible, unless one knew, to recognize the wheat-rust after it 

 had migrated to one of the other plants upon which it has ac- 

 quired the habit of developing. The three sorts of wheat-rust 

 which occur in Minnesota alternate on different plants, one de- 

 veloping on barberry leaves and probably also on the leaves of 

 some other species which has not been identified, another re- 

 appearing on buckthorn leaves, and a third on borage leaves. 

 It must be remembered that these are three different varieties 



