131 



involves other features on which a great deal of experimentation 

 must take place before the cheapest and most satisfactory meth- 

 ods are determined. 



GETTING RID OF THE HILO GRASS IN THE FOREST. 



One of these problems is getting rid of Hilo grass which has 

 followed cattle grazing into the forest and which prevents natu- 

 ral reproduction of our native forest trees. Not only cattle but 

 pedestrians have been responsible for carrying the seed of this 

 forest pest into the innermost sections of the Hawaiian woods. 

 There is hardly a foot of the trail from the Waiahole tunnel 

 over the Koolau Range to Waiawa Valley which does not now 

 contain Hilo grass which has sprouted from seed carried on the 

 shoes and trousers of those who have walked over the trail. It 

 may become advisable in the future to stop all travel in the native 

 forest to prevent this one thing alone. 



In order to get rid of the vast stretches of Hilo grass now 

 found on the borders of or within the native forest, as a prelim- 

 mary to reforestation, it will likely be necessary to expend con- 

 siderable money. What seems now to be the most feasible 

 method of accomplishing this is one which is in vogue in the 

 Philippines where over 40% of the area of the islands is covered 

 with cogon grass which is not only useless for grazing and 

 destroys the productivity of the soil in which it grows, but is a 

 fire menace and, worst of all, is the breeding place of the destruc- 

 tive locusts which yearly swarm over the islands. This method 

 is to burn the cogon grass just before the rainy season and broad- 

 cast the seed of the Ipil ipil, Leucaena glauca, which is also 

 common in these islands where it is known as haole or false koa. 

 It has been found that this small tree will not only kill out the 

 cogon grass within two years, but increase the value of the soil 

 by the fixation of nitrogen and remedy the toxic effects pro- 

 duced by cogon so that reforestation may proceed. No doubt 

 many Hilo grass areas in Hawaii could well be reclaimed by a 

 similar method. 



TREE INTRODUCTION. 



The introduction and dissemination of exotic trees, shrubs, 

 vines, and other plants to supplement our native flora must evi- 

 dently be done in the most careful manner so as to avoid the 

 establishment of any new pest such as the lantana. The intro- 

 duction of the different species of banyan of the genus ficiis has 

 been advocated, but it has not yet been proved that they are 

 entirely suitable for our wet forest region. It is questionable 

 whether the desired lower story of bushes, ferns, and under- 

 growth will come up under their dense shade and if their natural 

 spread is facilitated and hastened by the introduction of a flower- 

 pollinating wasp, it is not certain that they will not become a 

 pest in localities where they are not wanted. 



