WHEAT. 47 



field of wheat on rather a light and sandy soil came 

 up with every appearance of health, and also into 

 ear, with a fair prospect of ripening well. About 

 the beginning of July it was considered as exceeding 

 anything expected from such a soil. A week after- 

 wards, a portion of the crop on the east side of the 

 field, to the extent of several acres, was totally de- 

 stroyed, being shrunk and shrivelled up to less than 

 one half the size of what it had formerly been, and 

 so withered and blasted as not to appear to belong 

 to the same field. The rest of the field produced a 

 fair crop.'* This disorder attacks either the leaves 

 or stem of the plant, which appear to be covered 

 by broken lines, of a black or deep brown colour. This 

 disease has been ascertained to result from the presence 

 of a very minute species of fungus, the roots of which 

 are inserted into the stem, and absorb the nourishment 

 intended for the grain, which when the plant is thus 

 attacked proves little else than husk. The minute 

 seeds of the parasitical plant which occasion this 

 mischief are so exceedingly light that they are borne 

 along by the air to considerable distances. They 

 are likewise of extraordinary quick growth, occupying 

 in warm weather, according to the opinion of Sir 

 Joseph Banks, not longer than one week from the 

 time of their insertion in the plant to the production 

 of their seed. Every pore in the straw whereon they 

 fix will present from twenty to forty plants, so that 

 the extent to which this mischief spreads is diffi- 

 cult to be imagined. Fungus thrives best in damp 

 and shady situations, a circumstance which seems to 

 point out naturally the propriety of providing means 

 for the free ventilation of the fields, keeping low the 

 hedges and fences by which they are surrounded. 

 For the same reason it is found that thin crops, and 



* Encyclop. of Gard. p. 237. 



