VIII 



FOREST & ORNAMENTAL TREES 251 



materials, but these spores will grow on either dead or 

 living plants. When wounds occur these spores are 

 readily transferred by means of wind, insects, etc., to 

 the injured parts. Of course not all wounds are 

 inoculated with these germs of disease; in fact very 

 few of them are, otherwise it would be practically im- 

 possible to grow tree crops of any kind. 



Prevention. It would at first appear absurd to 

 attempt prevention of this class of diseases, but a little 

 thought shows that much can be done, and that much 

 more will be done in the future. (1) The destruction 

 of injurious insects, where possible, will have a twofold 

 value in that it will prevent the injuries by the insects 

 which make the entrance of the organisms of disease 

 possible, and also reduce the distribution of the 

 organism ; (2) careful pruning and the painting of 

 the wounds will prevent the entrance of the organisms 

 of disease ; (3) the removal of logs, stumps, dead 

 twigs, and other debris ; (4) the cutting out and burn- 

 ing of diseased parts as soon as the disease appears, 

 and painting the resulting wounds ; (5) the absolute 

 removal and destruction of badly diseased plants ; (6) 

 greater care in cultivation, tapping, and gathering of 

 fruits of both wild and cultivated plants. 



As timber becomes more scarce and more expensive 

 it will no doubt be found to be profitable to make use 

 of certain orchard methods in the care of forests, and 

 these methods can always be used to advantage on 

 shade and ornamental trees. 



The most important of these wound parasites are 

 the fungi. So little has been written on these diseases, 

 with special reference to tropical plants, that it will be 

 necessary in most cases to make these discussions very 

 general. 



Forties. This genus includes some of the most 

 destructive species known in the tropics. They are 

 wound parasites, and require considerable moisture ; 

 for that reason they are most abundant and most 

 destructive in dense, damp forests, and rather un- 



