On the Diseases of Wheat. 



13 



(or even the whole superficial tissue of plants) into imbibing 

 organs. If the autumnal fogs really pre-dispose wheat to the 

 attacks of the mildew-fungus, we must agree with those who re- 

 commend the growth of early varieties in places subject to these 

 fogs. It seems to be pretty generally admitted that spring- 

 wheats are less liable to mildew than winter-vvheats ; and that 

 heavy soils are less subject to it than light ones. But, at present, 

 the information on these points is very vague and unsatisfactory. 

 We may safely conclude, that a generally healthy state of the 

 plant, without any over-luxuriance of vegetation, is most likely 

 to secure a crop against the attacks of the rust and mildew- 

 fungi : but, that whatever tends to render the plant sickly, 

 whether it be excess of heat or cold, draught or wet, sudden 

 changes of temperature, poverty of soil, over-manuring, shade, 

 &c. &c., must be considered as a pre-disposing cause to these dis- 

 eases. Supposing it w^ere clearly ascertained that a corn- crop 

 bad imbibed the sporules of the mildew-fungus early in the sea- 

 son, might it not be advisable to feed it down by sheep ? I ask 

 the question in perfect ignorance of the propriety or practicability 

 of such a course. The rust, and mildew-fungi attack many 

 grasses, and I have this year found the latter in great perfection 

 in the Common Reed. It is evident, therefore, that we can never 

 expect to exterminate these fungi; but that their sporules will 

 always be found in our fields, ready to attack the corn-crops 

 whenever these are brought into a state adapted to receive their 

 influence. Whether remedial or palliative measures may not be 

 discovered is an enquiry well worthy the attention of agriculturists. 



Section VIII. — On th.e supposed influence of the Berberry in 

 blighting corn. 



A notion has long prevailed, not only in England, but on the 

 continent, that the berberry-bush (Berberis vulgaris^ is in some 

 way or other frequently connected with the production of mildew 

 in wheat. Sensible observers, among practical agriculturists, have 

 persuaded themselves that this is really the case ; and they have 

 asserted that their conviction of the truth of this hypothesis 

 rests upon the effects which they have themselves witnessed. 

 I should have considered such testimony of far greater value, 

 if I had found it opposed only by the contradictory convictions 

 of scientific inquirers ; for however unlikely it may seem to the 

 latter, that the berberry could in any way produce the ill effects 

 ascribed to its influence, there are too many mysteries in the 

 works of nature hitherto unravelled, not to induce us to pause 

 before we decide a thing to be impossible, merely because we 

 can see no reason for considering it to be at all probable. But 

 in the present case, even practical riien are by no means 



