INSULAR EXPERIMENT STATIONS. 25 



continued to give good results. Some attention is being giv^en to the 

 varieties of avocados in the Territory, and four have been found ta 

 have especial merit and they will be propagated as rapidly as possible. 

 Experiments are also in progress in improving the papaya. It has 

 been found that by the use of the pistillate plants in an orchard the 

 nonbearing staminate plants can be eliminated. Enough perfect 

 flowers are produced for the purpose of fertilization and the seed' 

 lings from such fruits are either all pistillate or perfect, and the 

 results of crossing are eliminated. Marked differences in quality, 

 shipping, etc., have been noted and the experiments are being con- 

 ducted to improve these characters. Shipping experiments w^ith 

 sweet potatoes were undertaken during the year, and it was found 

 practicable and profitable to ship them to San Francisco during the 

 early summer before the California crop has begun to come in. 



The entomologist continued his studies of insect pests of agricul- 

 tural croj3S with a view to their control. Especial attention has been 

 given the insects attacking sweet potatoes in Hawaii, and a bulletin 

 prepared on the subject. Attempts are being made to introduce para- 

 sites of the algaroba bean weevil, but the results thus far can not be 

 safely forecasted. Extensive additions were made to the collections 

 of economic insects, and much work in breeding and life-history study 

 is in progress. 



The cooperative work on the rubber plantations was continued. 

 The commercial plantings have all been made at elevations of 1,400 

 feet or below, and satisfactory growth is reported. The Ceara rub- 

 ber trees continue to grow more rapidly than the Hevea trees, and the 

 extensive planting of Hevea trees will depend on whether the yield 

 of rubber will ultimately be enough larger than that of Ceara to 

 warrant the longer waiting for the first tapping. The advantage 

 of clean cultivation of rubber plantations is shown by the much more 

 vigorous growth of cultivated trees. ^Vhere cultivation can not be 

 practiced owing to the rocky nature of the soil it was found desirable 

 to destroy the weeds by other means. Spraying experiments were 

 tried for the destruction of weeds among the rubber trees, and it 

 was found that the ground could be cleared of all weeds by spraying 

 with arsenite of soda. About 400 acres were successfully cleaned 

 in this way at a cost of about $1.25 per acre. 



The work of the station continues to be of great practical im- 

 portance, and the relations with the people of the islands are most 

 cordial and helpful. In order to bring the results of investigations 

 within the observation of many who can not otherwise be reached^ 

 the station has taken up the problem of establishing demonstration 

 farms in different parts of the islands. The funds are suj^plied by 

 the Territorial government, and it is proposed, as far as possible, to 

 work through the most successful farmer in the different homestead 



