370 



Blight. 



Vol. V. 



cannot see, inasmuch as the well-known doc- 

 trine that crossing the breed produces a hardy 

 progeny, favours the position he has taken ; 

 and his own experiment on poor sand and 

 rich compost beds strengthens the same. 



Vol. 5, No. 8, Vir appears, and ably sus- 

 tains the position with which I set out The 

 theme of his essay is the Hessian-fly, but it 

 is manifest that in the principle he advocates, 

 the fly, mildew, smut, together with those 

 insects which several of your correspondents 

 have referred to, as connected with blight in 

 pear trees, &c., all fall under the same cate- 

 gory — as diseases arising from an unhealthy 

 state of the plant. But Vir is able to speak 

 for himself. 



Observer, (same No.) relates his observa- 

 tions on certain varieties of mosses, from 

 which I am not able to make any inference, 

 and confirms Jacob List in his remark, that 

 unhealthy plants are most likely to be injured 

 by rust. 



T, (vol. 5, No. 3,) is so strongly impressed 

 with the doctrine of atmospheric causes, that 

 he (with prodigious temerity !) even laughs — 

 ay, and boldly, too, at an importation of Hes- 

 sian flies. (Pallas spread her shield over 

 him ; I wonder he has not been eaten up be- 

 fore this.) 



We now come to the grit of the contro- 

 versy. Tycho Brahe takes up the cudgel 

 versus Vir, and asks the question — " Perhaps 

 he would consider botts in horses, or worms 

 in children, as exceptions to this principle]" 

 Vir is, however, consistent, not only with 

 himself, but all sound physiology, whether in 

 •■he medical world (proper) or natural history 

 at large. The long discussion among medi- 

 cal men about miasmata, if it proved any 

 thing, proved this, that when the constitution 

 is in a healthy state, there is little liability to 

 agues, fevers, or infection of any kind. Thus 

 Vir is fortified by all sound analogy. I am 

 so unfortunate as to have lost No. 2 of the 

 present volume, and therein more articles on 

 the subject. 



Agricola, (vol. 5, No. 8,) espouses the doc- 

 trine of atmospheric agency, but to my sur- 

 prise conceives " rust" to be a blemish aris- 

 ing from the exudation of the sap! Is this 

 your old correspondent 1 Yet he writes well. 

 Pomonius observes (extract from Mr. Pear- 

 son) casually, while treating of the canker 

 in pear trees, " but as I do not approve of too 

 good a soil in a cold climate," &c. — thus up- 

 holding the doctrine of a rank soil being 

 favourable to blight. 



Next, we have Col. Smith's theory respect- 

 ing the influence of grass among wheat; — 

 whether true in whole or in part, it goes in 

 favour of the theory advanced by Vir. 



(No. 11.) In the last No. p. 340, the edi- 

 tor of the Agricultural Journal attributes the 



animalculae in sedgy oats to a poisonous sub- 

 soil. " The presence of the insects, we con- 

 ceive to be the effect and not the cause of the 

 disease." 



I have thus hastily run over the ground 

 heretofore occupied by your correspondents. 

 To what conclusion do we then arrive ? I 

 trust that any of your readers who desire to 

 arrive at correct conclusions, will reperuse 

 carefully all that I have referred to. I think 

 that we shall be safe in assuming the follow- 

 ing principles. 1st, That rust, mildew or 

 blight, together with smut, are parisitic fun- 

 gi ; 2d, that the immediate cause of their at- 

 tack on wheat is the still, warm, moist state 

 of the atmosphere, at the time of its appear- 

 ance; 3d, that the mediate or accidental 

 causes are moist, low meadows, (causing a 

 stagnant atmosphere with redundant mois- 

 ture), weeds, high grass, close hedges, par- 

 ticular exposures, poisonous subsoil, &c., &,c. ; 

 and 4th, that the ultimate or original cause 

 is an improper rotation of crops with stimu- 

 lating manures, inducing an unnatural, 

 rank and tender condition of the wheat 

 plant, thereby exposing it, by its increased 

 susceptibility, to the attacks of the fly, mil- 

 deio, or smut, 



I have written without the references be- 

 fore me, and with such brevity that I fear I 

 shall not be understood, unless those articles 

 are examined in connection. My object has 

 been to show, that there is an array of evi- 

 dence before your readers almost amounting 

 to a demonstration, and much of it extracted 

 from adverse writers, that these principles 

 are correct. If so, the next step will be, to 

 devise such a system of crops and mode of 

 culture as will best fulfil the indications. 



And now for a little speculation. I have 

 been but two years on the farm I now occu- 

 py, and it is a soil with which I had not been 

 familiar : I suspect it is not the most favour- 

 able to wheat. And here, in parenthesis, let 

 me remark, that the most favourable soil in 

 the range of my observation (Chester co.) is, 

 the mica slate range of hills, south of the 

 great valley, which is seldom found so rich 

 and rank, even with the aid of raw manure, 

 as to spoil a wheat crop. The rotation of 

 crops which I have devised is this, counting, 

 as we usually do, from the grass crop. 1st 

 year, wheat, turnips ; 2d, corn ; 3d, oats ; 

 4th, roots — potatoes, beets, ruta baga ; 5th, 

 barley, with clover seed ; 6th and 7th, clover, 

 mowing first and second crops, and manuring 

 through the first or second winter, and then 

 a crop of wheat from the clover lay. Ac- 

 cording to the English mode of cropping, 

 the root crop would be mentioned Ist, — the 

 basis of the system, — being the manured, 

 and the cleansing crop. I should omit oats, 

 but for the extra labour of hauling off th« 



