98 REPORT OF OFFICE OF EXPERIMENT STATIONS. 



Fertilizer experiments with rice showed definitely that the applica- 

 tion should be made before the rice is planted and that ammonium 

 sulphate or an organic fertilizer is a better source of nitrogen than 

 nitrate of soda. Fertilizer experiments with taro gave the same re- 

 sults as those with rice, and thorough drying and aeration of the soil 

 between crops, together with proper fertilizing, was found to prevent 

 taro rot. 



The chemical investigations on manganese soils indicated that pine- 

 apple is exceptionally sensitive to unfavorable soil conditions and can 

 not be made to thrive where from 4 to 5 per cent or more of man- 

 ganese is present. It was found that the best results with pineapples 

 on manganiferous soils can be obtained from planting the old stumps 

 rather than the suckers, and by fertilizing heavily with phosphates. 

 It appeared from an examination that improper drainage of soil is a 

 conspicuous cause of some of the pineapple troubles in the district 

 of Wahiawa. It was further determined that pineapples did not re- 

 quire as much water as has been formerly supposed and that with 

 proper drainage they can be successfully growni under a heavy rain- 

 fall. Progress was made in accumulating data for a general classifi- 

 cation of Hawaiian soils. 



The most important feature of the entomological work during the 

 year was the discovery of the Mediterranean fruit fly, which attacks 

 peaches, all of the citrus fruits, mangoes, peppers, guavas, figs, and 

 avocados. A plan devised by the station for the control of the pest 

 consists essentially in the collection and destruction of fallen fruit. 

 Studies were made of the insect pests of corn and leguminous plants, 

 and attention was given to the subject of insect parasites, including 

 a parasite destrojdng from 5 to 10 per cent of the bollworms. 



The horticultural investigations were continued with tropical 

 fruits. A budding method for the avocado was perfected and a 

 successful inarching method was devised for rapidly testing promis- 

 ing seedlings. As far as possible, all types of avocados found in 

 Hawaii have been collected and a system of classification and de- 

 scription is being worked out. Studies of papaj'a fiiiits showed that 

 the variation in flavor, size, and shape is almost unlimited. The 

 station found it possible to propagate papayas by the use of moncE- 

 cious trees without the help of sterile male trees. Spraying experi- 

 ments showed that the rusty blight of avocado leaves can be con- 

 trolled with the use of Bordeaux mixture. The station gave assist- 

 ance in the distribution of suckers of the Bluefields banana and in 

 culture experiments. From the results of this work it seems evident 

 that a wider spacing in planting should be adopted. 



A number of miscellaneous investigations in progress included ex- 

 periments with broom corn, leguminous forage crops, weed destruc- 



