Weir: Introduction of Wood-Destroying Fungi 59 



of the most valuable timber trees of that region, and evidently 

 causes a serious rot. It has also been observed that in one case 

 square timbers showed incipient or initial decay by fungi not 

 known to occur in the foreign country to which the timbers were 

 shipped. The ease with which lumber may become infected, 

 .while stored in insanitary yards, is only another example of how 

 wood-destroying fungi may be transported from one country to 

 another. 



Distribution of Wood-destroying Fungi 



In contrast to the higher plants, many of the wood-destroying 

 fungi are widely distributed throughout the world. For example, 

 Pontes annosus Fr., Fomes (Tramefes) Pini (Brot.) Lloyd, and 

 Armillaria mellea (Vahl.), three of the most destructive forest 

 tree fungi in America and Europe, are reported from various 

 tropical countries. In the latter regions these species are appar- 

 ently not abundant, a condition which is difficult to explain. On 

 the other hand, there are a number of serious wood-destroyers 

 and parasitic species which are confined to the tropics or to foreign 

 countries in general. There is no reason why these species should 

 not find a favorable environment in some of the varied climates 

 of the United States, if once introduced. It is well known that 

 in the case of some parasitic fungi a change from one country to 

 another of dififerent chmatic conditions may often be favorable to 

 the fungus, which may develop into a serious pest. This could be 

 true of many foreign wood-destroying fungi. 



Possible Explanations for the Apparent Small Number of 

 Wood-destroying Fungi in the Tropics 



Contrary to the general opinion and as compared to the condi- 

 tions in the temperate zones, the number of species of this group 

 in the tropics may not be considered particularly abundant. 

 Westerdijk^ explains this condition through the assumption that in 

 the tropics "the heavy rainfalls, combined with the abundant 

 transpiration — owing to the intense heat, must cause a high water- 



1 Westerdijk, Johanna. Phytopathology in the Tropics. Ann. Mo. Bot. 

 Gard. 2: 308. 1915. 



