On the Disease of Rust. 61 



generally flat and moist, where the plants stand too thin 

 and scattering, and, in consequence of being thus thin, 

 have too much stalk and leaves ; or under the shades of 

 trees, or round the margins of the field. 



In all these cases, the plants will be greener, and ap- 

 pear to possess a greater degree of succulency, than in 

 other parts of the field. In short, every cause which 

 retards the maturity of the grain, renders it more liable 

 to rust. In this way, it is highly probable, that plas- 

 tered wheat will sometimes sustain injury from that 

 cause. Plaster, certainly, does render the plants more 

 vigorous and succulent, and thereby retains them longer 

 in a green state. The reverse is the case with common 

 manures : for instance, dung. If partial spots in a field 

 be dunged, previous to seeding the land, those spots 

 will come first to maturity, and rarely (if ever) will such 

 spots be rusted. I will venture to account for these 

 different effects. Dung is applied in the fall, and, in 

 consequence of that, produces a thick crop. This it 

 does two ways : first, by invigorating the plants, and 

 multiplying their branches ; and, secondly, by prevent- 

 ing the effects of severe frosts, which generally destroy, 

 in the course of the winter, a large proportion of the 

 plants ; frequently one-half. Even dry straw, or dry 

 weeds, or brush-wood, strewed upon the surface of the 

 wheat, in the beginning of the winter, will preserve it 

 from the injuries of frost. Plaster is generally applied 

 in the spring ; but even if the application were made in 

 the fall, I do not think (from some experiments which 

 I have made), that it will guard the grain from the ef- 

 fects of frost, in any powerful degree. Perhaps, by in- 



