446 THE MAN GOLD- WURZEL CROP. 



creased cultivation we shall no doubt become less attentive 

 to its general health, and more careless of those conditions 

 of cultivation manures, soil, seed, &c. which increase 

 in importance as our crops are forced from their normal 

 habits of growth. We have had notices that this disease 

 has already been met with in our mangold crop, and the 

 best way to keep free from it will be to sustain the vigour 

 and health of our plants by growing them in soils suitable 

 for them, taking care that they are supplied with proper 

 food, making the interval between their occupation of 

 the same ground as long as possible, and by using only 

 seed upon the quality of which we can place reliance. 

 If these conditions are observed, the chances of disease are 

 at once proportionably diminished, as these parasitic fungi 

 never attack sound and healthy plants. 



The comparative freedom from disease and from the 

 attacks of insects, were no doubt favourable circumstances 

 to the introduction of mangold into this country; and until 

 within these last fifteen or twenty years, it was supposed 

 that its chances of injury were so few and of so little 

 importance, as practically not to interfere with its culti- 

 vation at all. As the breadth sown increased every year, 

 more attention was paid to it, and it was soon found that 

 it enjoyed no such perfect immunity from insect injuries 

 as was supposed; and that although we at present are 

 not so well acquainted with its enemies as we are with 

 those infesting either the turnip or the potato crop, still 

 we find continually, on comparing notes with each other, 

 fresh instances of injuries sustained, and that our list of 

 predatory insects increases every season. 



As soon as the young plants appear above the ground, 

 they are attacked by the grubs of the "crane-fly" Tip- 

 ula oleracea (p. 386), and by the surface-caterpillars of 

 the heart-and-dart moth Agrotis segetum and A. excla- 

 mationis. The upper part of the root is eaten through, 



