FUNGOID PESTS 



The Vegetable Beef-steak or Oak Tongue (Fistuhna hepatica) is found 

 on living Oaks, not infrequently in the same position, year after year. It 

 first appears as a reddish knob, rather like a strawberry, but soon enlarges, 

 becoming darker in colour, sticking out horizontally from the tree, and 

 much resembling the tongue of an animal in shape and appearance. As it 

 ripens it becomes more succulent, being soft and easily cut, internally 

 mottled somewhat after the manner of beetroot, and though it perhaps 

 more closely resembles a piece of bullock's liver, it is not difficult to 

 account for its common name of Vegetable Beef-steak. It usually 

 weighs from three to four pounds, but specimens have been found weighing 

 as much as thirty pounds. Though bitter and astringent when young, it 

 is said to be quite nice if stewed with butter when thoroughly mature. 

 The under surface is perforated with innumerable minute holes — the mouths 

 of the closely packed tubes — which bear the salmon-coloured spores on their 

 inner sides. Being always found on the dead parts, it is doubtful to what 

 extent the fungus is a cause of injury to the tree. 



Willow-leaf Blotch (Rhytisma salicinum) is found on the Goat Willow 

 and several other species of Salix. The blotches are large, circular, or 

 irregular, rather shining and pitchy-black, the internal stroma being white. 

 The ascigerous stage is found on the fallen leaves which have passed the 

 winter on the ground. The clavate asci contain eight needle-shaped, curved 

 sporidia. Diseased leaves should be collected and burned. 



Willow Mealy Mildew or Blight (Uncinula adunca) attacks the foliage of 

 Willows, Poplars, and sometimes Birch. The mycelium is rather thin and 

 white, and the falling conidia increase the mealy appearance of the leaves. 

 The minute, dot-like receptacles are surrounded by a rather dense circle 

 of unbranehed, hooked appendages. Each receptacle contains 8-12 asci 

 furnished with four spores. 



Witches' Broom of Birch (Exoascus turgidus). This is a somewhat similar 



growth to the " Witch Knots " already described in the chapter on Galls, 



but in this case the abnormal growth is the result of a fungus belonging 



to the great group of Ascomycetes. In the genus Exoascus the asci, or spore 



lxxvii 



