THE COMMON ALDER. 339 



seeds should receive a light covering of not more than one- 

 third of an inch, and they germinate, if sown in spring, after 

 4 to 6 weeks. 



In nurseries a moist part should be chosen for the seed 

 beds ; at any rate they must be kept moist after sowing. The 

 seed is sown broadcast. When one year old, the seedlings 

 may be pricked out, and left one or two years in the nursery 

 lines. 



The planting is mostly done in pits. 



/. Tending. 



Alder does not require much tending. When quite young 

 it is liable to suffer from frost lifting, owing to the moist con- 

 dition of the soil where it is usually grown. This can be 

 prevented by covering the space between the plants ; any 

 plants actually lifted must be promptly put back into the 

 ground. 



Considerable danger may threaten alder from the drying 

 up of the subsoil owing to a change in the level of the ground 

 water. Such danger must, as far as practicable, be avoided, 

 by preventing the water from being drained away. At the 

 same time inundation may do much damage, especially if it 

 occurs after a wood has been coppiced, and if the water 

 covers the stools, or if sheets of ice form over young 

 plantations. 



Insects and fungi do little damage. The foliage of alder 

 may be injured by Tortrix larv?e, or by the plant-beetles, 

 Agelasticd-aliii and Lina cenea, both uncommon in England. 

 The bark of young alders is attacked by a weevil, Cryptor- 

 rJiynduis lapathi, which breeds in their stems. Older trees 

 are bored by the Cossidce and one or two Sesias. 



Of fungi Nectria ditissima may cause cankerous formations, 

 and Pnhipnrus sulphureus red rot in the stem. Exuascus 

 borealis causes witch's broom, and several other species of this 

 genus are found on the leaves and flowers. 



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