122 ARTIFICIAL REMEDIES FOR 



disease ; but I have found thousands of plants damaged 

 which had been left in the ground all the winter from pre- 

 vious crops. Hence, taken by itself, this plan forms no 

 protection, though, by tending to forward the growth of 

 the plant, it may help to cheat the destroyer, and lessen 

 the mischief. 



(478.) The best means of destroying the cause is to 

 pick off the insect when we desire to protect a single plant. 

 To pull off affected leaves, or to sprinkle them with quick- 

 lime, when we wish to protect a larger number of plants. 

 We should endeavor to get our produce ripe at an early 

 period by using early kinds, and by planting early, perhaps 

 even in autumn. We should protect lady-birds, ichneu- 

 mons, and soft-billed birds ; and we may try the effect of 

 ducks to gobble up the parasites. 



REMEDIES AGAINST CONTAGION. 



(479.) We must remember that the mischief is eminent- 

 ly contagious, and that the destroyer may spread from one 

 crop to another j therefore, especial care should be taken 

 to prevent contagion. I have often traced the disease in tur- 

 nips to their proximity to potatoes, disease in beet to its 

 proximity to turnips ; and I have traced the disease radiat- 

 ing from old infected haulms heaped together for manure. 



(480.) Whenever potatoes are dug up, the infected 

 haulms should be instantly burnt, in order to destroy the 

 insect ; and, perhaps, it would be a good plan when we 

 find even the living haulms excessively affected, at once 

 to pull them up and burn them. Marshall has long ago 

 proved that cutting down the haulm lessens the crop of 



