158 ON THE RUST OR 



" tinguished naturalist (Sir Jos. Banks), that this 

 " disease is occasioned by the growth of minute 

 " parasitical fungus, or mushrooms, on the leaves, 

 " stems, and glumes, or chaff, of the living 

 " plants ; and that the roots of the fungus, inter- 

 " cepting the sap intended by nature for the 

 " nutriment of the grain, render the grain lean 

 " and shrivelled, and, in some cases, rob it com- 

 " pletely of its flour. Nor is that all ; the straw 

 " becomes black and rotten, unfit for fodder, or 

 " little better than a caput mortuum, possessing 

 " neither strength or substance." 



Again, " Several of the accidents, above 

 " enumerated, may contribute to the production 

 " of rust ; but there are two additional circum- 

 " stances which likewise tend to promote it. 

 " First, Having the land in too rich a state for 

 " corn crops ; and, Secondly, When too fre- 

 " quent a repetition of crops of wheat takes 

 " place." 



" It has been well observed, that when crops, 

 " intended to ripen their seed, are objects of 

 " Culture, there is not only wanted a degree of 

 " vigour and luxuriance in the plants sufficient 

 " for the pin*pose ; but if the fertility of the soil 

 " be raised to a higher pitch than is necessary or 

 " consistent with that object, injurious rather 

 " than beneficial consequences may be the result. 



