ON PESTS GENERALLY. 



II09 



extremely common. According to the Cornell Agricultural 

 Bulletins, the time to spray is before the blossoms open, and 

 again when they have fallen. This should suffice in dry seasons ; 

 but in wet ones it may be necessary to spray three or four 

 times more at intervals of about ten days. 



Armillaria mellea (Agaricus melleus). — This is a most 

 destructive fungus found upon living ornamental trees, such as 

 Conifers, as well as upon orchard trees. It is responsible for the 

 disease known as Tree Root Rot. The fungus (Fig. 720) is most 

 abundant, and is 

 found both as a 

 saprophyte and as 

 a parasite. The 

 clusters of Mush- 

 rooms at the base 

 of trees are very 

 familiar ; they are, 

 moreover, con- 

 spicuous alike as to 

 size and colouring. 

 The cap is of a pale 

 yellow, with darkish 

 scales upon it ; the 

 stem is also yellow. 

 The fungus finds 

 access to healthy 

 trees either by means 

 of its spores, which 

 germinate on an in- 

 jured part of the 

 bark ; or by means 

 of the very peculiar 

 mycelium, which is 

 black and stringlike, 



and always endeavouring to penetrate the roots of healthy trees. 

 The only thing that can be said in favour of this fungus is that 

 its sporophores, or Mushrooms, are edible, though not particularly 

 rich in flavour, being somewhat strong. Care should be taken 

 to carefully remove and either eat or burn all specimens of the 

 fungus, so that the danger of trees being infested by the spores 

 which are shed is minimised. The mycelium found under the 

 bark is white and felted. 



Once a tree has been badly attacked nothing can save it from 

 destruction, as the mycelium spreads under the bark with 

 considerable rapidity. Preventive rather than remedial measures 

 should be adopted. These may well consist in the removal of 

 all dead stumps (Fig. 720) on which the fungus is growing as 

 a saprophyte ; and in isolating the infected live trees by means 



Fig. 



720. — Mass of Armillarta mellea 

 Root of Young Pine. 



a, a, a, Mycelium in form known as Rhizomorphs; 



6, Very young Spore-bearers produced on Rhizomorphs ; 



d, Older Spore-bearers (Agaricus melleus) produced ^ by 

 Mycelium under the bark. 



