CAUSES OF RUST IN WHEAT. 179 



raised to a higher pitch than is necessary or consistent with 

 that object, injurious rather than beneficial consequences 

 may be the result. Land may be too rich for corn crops ; 

 and it is better to keep it in a well balanced condition, or 

 in a medium state of productiveness, than in too fertile a 

 state. The greater quantity of sap and juices in vegeta- 

 bles growing on highly cultivated lands, it is evident, must 

 necessarily render them more susceptible of the effects of 

 sudden and extreme changes, and consequently more liable 

 to disease. Besides, as mushrooms are produced on beds 

 of dung, great quantities of manure must promote the 

 growth of fungi or parasitical plants, on the crops of wheat, 

 if they are once infected. The wheat produced on the site 

 of a dunghill is always rusted, even in the most favour- 

 able seasons : and if the whole field is a species of dung- 

 hill, how can it escape ? " 



A too frequent repetition of crops of wheat, more espe- 

 cially when accompanied by great quantities of manure 

 to force a crop, will often have the same effect. The 

 rust was but little known in the western or the northern 

 parts of England, or the southern counties of Scotland, until 

 of late years, when every exertion has been made to in- 

 crease the quantity of that grain." 



Sir John Sinclair also says, " Among the remedies likely 

 to diminish the effects of this fatal malady, the following 

 have been particularly recommended : 1, Cultivating hardy 

 sorts of wheat ; 2, early sowing ; 3, raising early varieties ; 

 4, thick sowing ; 5, changes of seed ; 6, consolidating the 

 soil after sowing ; 7, using saline manures ; 8, improving 

 the course of crops ; 9, extirpating all plants that are re- 

 ceptacles of rust ; and 10, protecting the ears and roots of 

 wheat by rye, tares, and other crops." 



And again, he says, " It is likewise stated on the re- 

 spectable authority of an eminent naturalist (J. A. Knight. 

 Esq.), that by crossing different varieties of wheat, a new 

 sort MAY be produced, which will completely escape being 

 rusted, though the crop in the neighbourhood and in al- 

 most every district in the kingdom may suffer from it in 



