The Potato. 11 



the vine, next on the potato, again on the vine, and then 

 applied to potatoes, vines, and mulberries in the open air, 

 he in any way distinguished from disease produced hij natural 

 means in the open air. It was also remarked in very many ex- 

 periments, that if the supposed bloom was placed on the upper 

 part of a leaf under favourable circumstances, it produced no effect 

 on that leaf, but would infect frequently the leaves above. It 

 is said above that sulphur in a confined place is a sure and 

 effective remedy, yet it fails in the field although greatlv 

 diversified in application (see p. 73), nor although closely 

 observed has the cause of the failure been detected ; yet it 

 operates remedially in the garden, on the potato, vine, lilium, 

 or verbena, evincing a contradiction not at this moment capable 

 of a satisfactory solution. Failing, then, all chemical remedies 

 when applied on the large scale, and it being certain that the 

 disease in no case ascends from the root but descends from the 

 leaf to the tuber, the experiment at VVhilborough (see p. 74) 

 again became important; and it was repeatedly confirmed by the 

 favourable results attendant on the deep planting (see p. 75), and 

 the inquiry now arose, " Can we by any peculiar course of culture 

 save the majority of our crop ? " Experiments were at once 

 instituted on a very extensive scale to test this question, and 

 also to ascertain if the same advantages could not be derived 

 without making the potato so inordinately large, and of course 

 unsaleable. 



It was observed in taking up many acres of potatoes by many 

 men, that no potato covered icitli more than three inches of soil 

 icas ever diseased ; and on repeating the experiment with very 

 great care, I felt assured that no potato covered with tliree inches 

 of soil becomes diseased, and that their experience was correct. 

 Experience has taught me how difficult it is to observe correctly, 

 but no fear need be entertained tliat this idea can be controverted, 

 and the effect on the crop must be seen to be appreciated ; for 

 instead of two-fifths of the entire crop being wasted, as was the 

 case last year (185G), it is rare indeed to find a diseased potato ; 

 so rare, in truth, that an attentive examiner will soon detect the 

 cause of that one diseased potato. I have seen scores of bushels 

 of potatoes dug ; but I have never seen or heai'd of one diseased 

 potato being found four inches under the surface of the ground. The 

 experiment is easily made : make a deep trench l^y the side of 

 any row of potatoes, and parallel thereto ; then with a trowel or 

 pointed stick take down perpendicularly the soil. It icill be at 

 once seen, and too muck stress cannot he laid on the fact, that the 

 disease is in an exact ratio to the pjvximitg of the tubeis to the 

 surface. To elucidate this, on September 18, 1857, three pits 

 were made 10 inches deep, and about the same in diameter. 



