DISEASES OF WHEAT. fl|69i 



examined a number of wheat fields at different times, and 

 found tlie' straw untouched by the blight, and in every re- 

 spect in a healthy state. Every thing continued to have a 

 promising aspect till the heavy rains which fell a few weeks 

 before the eommencemcnt of harvest; the dark coloured 

 blight then began to show itself, and continued to spread 

 considerably ; and, if we may judge from its progress, had 

 the cutting down the crops been delayed a fortnight or three 

 weeks longer, it would have proved equally destructive with 

 that which took place in 1804. A sufficient number of facts ' ^ 



is yet wanting to warrant any conject'.ire on the manner in 

 which the fungi were produced by the heavy rains; however, 

 we may be pretty well assured, that all diseases which de- 

 pend so much on the state of the atmosphere, must ever 

 baffle human ingenuity to prevent. The earlier the crops 

 are ripe, the less liable will they be to be injured, and the 

 only remedy at present known is, to cut down the crop when- 

 ever the blight begins to make any progress. 



Although the above are all the principal diseases of wheat, Appearance of 

 at least as far as my observation goes, I cannot take leave ^^tiy prrished 

 of the subject without noticing a very common appearance plantsinacrop 

 in wheat crops, which is more or less frequent every season, ^ ^ ^'^ * 

 and varies considerably in different fields. Some time after 

 the corn is come out in ear, but yet in a green, unripe state, 

 we frequently observe several plants entirely white, with 

 every appearance of having perished. As harvest approaches, 

 and the corn changes to a bright yellovv, these plants, par- 

 ticularly after rain or heavy dews, put on a blackish appear- 

 ance, as if sprinkled with a black powder. Upon examina- 

 tion by the microscope, this appearance is found to be occa- 

 sioned by innumerable tuffets of a parasitic plant growing 

 out of the poies of every part of the plant which is exposed, 

 to the action of the air, very much resembling some species 

 of the plantulae of mould ; even the sap vessels of the stravr 

 are frequently filled in different parts with a black substance, « 

 easily discernible by placing the straw between the eye and 

 a strong light. The grains, as might be expected, are small 

 in size, and of a reddish brown colour. Most probably this 

 affection arises from some dcQay at the root, but whatever 

 that may be I have not hitherto discovered.,^. I, have fie- 



/ ' quently 



I 



