No. 9. 



The Potatoe Disease. 



273 



For the Farmers" Cabinet. 



The Potatoe Disease. 



Mr. Editor, — Those who have but re- 

 cently commenced the study of atrricultural 

 chemistry, may ask, if "Chemico" is correct 

 in his theory, that the potatoe disease is 

 caused by a surplus of carbonic acid, how is 

 it that the potatoes do not become diseased 

 earlier, for it cannot be denied that the car- 

 bonic acid is generated during the entire 

 growing season] I will endeavour to an- 

 swer this query. It is well known that the 

 carbonic acid which is generated prior to 

 the first of July, for instance, is divided 

 among all the varieties of plants that grow 

 in our climate. There being such a heavy 

 demand for it, no plant can get enough, ap- 

 parently, to injure it — hardly as much as it 

 can use for a good purpose. But after the 

 .first of July, for instance, some of these 

 plants seed and die, and commence decay- 

 ing. Now it will be perceived, that all 

 plants of this kind — and you are aware that 

 there is a very heavy proportion of them — 

 such as our wheat, rye, oats, and hay crops, 

 and a thousand others, not only do not take 

 their share of carbonic acid, and consequent- 

 ly those plants which grow till fall, have a 

 larger proportion — but many of them com- 

 mence rotting immediately, and add to the 

 increased supply of carbonic acid which has 

 been thrown upon the fall plants. 



In former years, even this increased sup- 

 ply of carbonic acid after harvest, was not 

 sufficient to disease the crop of potatoes, 

 unless other circumstances, local in their 

 nature, assisted it, but latterly, a supply of] 

 carbonic acid has been opened, that assisted} 

 the already great supply from the decay of 

 dead plants. I refer to the increased con-j 

 sumption of stone coal. This, together with 

 extensive manuring, appeared to have added 

 60 enormously to the supply of carbonic acid, 

 that the plants, already strained to the ut- 

 most in the fall season, could not any longer 

 resist the evil influence, and those most sub- 

 jected to its virulence have given way to a 

 power, which, while it should have exer- 

 cised a beneficial influence, has, through 

 the want of knowledge, proved a dreadful 

 and destructive enemy. 



The supply of carbonic acid, it appears, is 

 not yet sufficiently heavy to exercise an un- 

 favourable influence, until it is assisted by 

 that arising from the decay of the early ve- 

 getation, or until all, or nearly all, of the 

 causes of the formation of carbonic acid are 

 acting together. That this will not always 

 be the case, unless vigorous measures be 

 taken, I am strongly inclined to believe. 

 The large and increasing consumption of 



stone coal is adding every year to the car- 

 bonic acid ; and the time is not far distant 

 when the potatoes will become diseased be- 

 fore the tops are fully developed, and other 

 vegetation will sufier in like proportion. At 

 present this supply has increased the growth 

 of the early vegetables. During the early 

 part of the past season, I noticed the ex- 

 tremely luxuriant appearance of the early 

 vagetation. Every one noticed it, and it 

 was the subject of general remark. Every 

 thing of a vegetable nature grew as I never 

 knew it to grow before, and plants which, 

 in former years were rather small, last sea- 

 son grew to an enormous size. The hay 

 crop was extremely large. This vegetation, 

 when it came to decay, could not produce 

 any other than an unfavourable effect. Its 

 increased size must inevitably increase the 

 supply of carbonic acid, and 1 mentioned at 

 the time to my friends, that this extreme 

 luxuriance boded ill to the potatoe crop, and 

 that if the weather was not so extremely 

 dry and cool as to cut short the crop by 

 drought, the potatoe disease would be un- 

 usually severe. The result has been as I 

 anticipated, and the potatoe crop has been 

 very much shortened in consequence of the 

 early attacks of the disease. It has short- 

 ened the crop by attacking the tops in some 

 instances, and killing them almost as soon 

 as the tubers began forming ; so much has 

 this been the case, that many farmers have 

 no potatoes to dig — none having been formed. 

 This is where the disease has been unusu- 

 ally severe. 



But though the disease has attacked the 

 crop later this year than it will do, in all 

 probability, in future years, still it attacked 

 the crop earlier this year than it did in 1842, 

 as any one may see who will examine the 

 Reports of the Commissioner of Patents. 

 I And the disease will go on attacking the 

 crop earlier and earlier every year, until at 

 last there' can be no potatoes raised, unless 

 ja proper system of cultivation be adopted. 



I have but the last two Reports of the 

 Commissioner of Patents by me, and having 

 no other source of information on this sub- 

 ject, I cannot tell how early in the season 

 the disease commenced generally, during 

 1842 and 1843, but in 1844, I learn that it 

 began in the latter part of August and the 

 early part of September. This year, 1846, 

 it began about a month earlier, as we have 

 satisfactory accounts of its ravages as early 

 as the lalter part of July and the early part 

 of August. Thus, I am inclined to believe, 

 it will begin earlier and earlier every sea- 

 son, until the supply of carbonic acid from 

 the consumption of stone coal, will be suffi- 

 cient of itself, without waiting for the death 



