AGRICULTURAL TEXT-BOOK. / * 



Botanists Uredo rubigo; it is of an orange yellow color; and 

 when severe, causes the grain to shrink, and prevents matura 

 tion. The other (d,) Uredo linearis is confined to the straw 

 and leaf, and is the color of the rust of iron. It causes the 

 epidermis to split, and it is supposed to permit the emission of 

 the juices. The grain is affected by this in the same manner 

 as by the former. 



Wet soils are most subject to these fungi, but they especially 

 appear during sultry, wet weather towards the flowering of the 

 plant. 



200. Mildew (i.e. m el-dew, from an old notion that it was 

 produced by honey-dew falling from the air,) or Blight, (c,) is 

 produced by Puccinia graminis. It forms blackish brown pa 

 rallel, lives upon the straw, and seems to affect the entire plant, 

 BO that it deprives the sap of the power to form seed in a 

 healthy state, and hence the grain is very much shrivelled, or 

 no grain at all is formed. The spores of this fungus enter the 

 straw by its breathing pores, which are closed in dry weather, 

 but opened in a wet or damp atmosphere. This disease, like 

 the last, attacks the plant in warm, moist weather, and often 

 with remarkable suddeness and severity. Wet soils, and over- 

 manured land are chiefly subject to it ; and earth containing 

 a large proportion of the salts of iron appears to add to the ten 

 dency. Draining is probably the only cure. 



201. Wheat is also subject to attacks from various insects. 

 The injury caused by these is sometimes so great and perma 

 nent as to prevent the culture of wheat at all, as has been the 

 case in some parts of New England and New York. We shall 

 shortly enumerate those most common in the United States, re 

 ferring the student for scientific descriptions to Dr. T. W. Har 

 ris 1 Treatise on some of the Insects of New England which 

 are injurious to vegetation, 2d. Ed., Boston, 1852, and for 

 further information to the Patent Office Reports from 1844, 



