OFFICE OF EXPERIMENT STATIONS. 833 



and the area devoted to pineapples is being rapidly increased. In 

 this expansion of the industry the station has taken an active part 

 in determining soiiie of the causes of failure of pineapples to grow 

 in certain soils, particularly those containing large amounts of man- 

 ganese. Hitherto it was believed necessarj^ to avoid soils that con- 

 tained more than 2 per cent of manganese if success was to be ex- 

 pected in pineapple growing. Experiments are now in progress 

 which promise to furnish a means of rendering even the highlj^ man- 

 ganiferous soils available for pineapple culture. The station is car- 

 rying on breeding experiments to secure a strain of pineapples less 

 subject to the effects of manganese, and also if possible a more imi- 

 forni strain of pineapples than those now planted, in order to pre- 

 vent waste in canning. 



The experiments with cotton have shown the difficulties met with 

 in establishing a new industry upon a commercial basis. The experi- 

 ments thus far have shown conclusively that a good yield of excellent 

 cotton may be produced on lowlands and in protected localities, but 

 that exposed areas, particularly at elevations of 500 feet, should be 

 avoided in planting this crop. On the whole, Caravonica cotton has 

 given better satisfaction than Sea Island, and last year's crop was 

 sold at the station at 18i cents a pound, and was reported equal to 

 the best Eough Peruvian for use in mixing with wool. Later, offers 

 of 20 cents a pound for the same grade of cotton were received. The 

 methods of pruning worked out at the station and the use of lantern 

 traps liave demonstrated means for controlling the cotton bollworm 

 provided they are systematically applied. 



A study was made of the pulp which accumulates as a result of 

 decorticating sisal leaves, and it was found to contain high percent- 

 ages of mineral plant food in a readily available form, and its value 

 as a fertilizer was clearly demonstrated. 



Further tests of varieties of rice imported directly from Japan 

 indicate that these rices when grown in Plawaii give a product equal 

 to that imported from Japan in the milled form, and it is probable 

 that the importation of milled Japan rice will not be'necessary to the 

 same extent that has been considered necessary in the past. Fertil- 

 izer experiments have again shown conclusively that ammonium sul- 

 phate is the best form in which nitrogen can be applied to this crop, 

 and tliat nitrate of soda is quite unsuited to the purpose; moreover, 

 that the fertilizer should be applied to the rice during the early 

 growth of the plant rather than at the later stages of growth, as is 

 the oriental practice. 



In cooperation with Territorial authorities the station has devoted 

 considerable time to the study of the habits and life histories of mos- 

 quitoes, and also to the problems connected with the Mediterranean 

 fruit fly, which pest has made its appearance in Hawaii. Arrange- 

 ments have been made for the breeding and distribution of parasites 

 of the Mediterranean fruit fly, which it is hoped may be obtained 

 from Africa. 



In connection with quarantine work the station has developed a 

 method of clean culture for liananas by moans of which scale infesta- 

 tion can be avoided and which will make it possible to grow bananas 

 which will readily pass quarantine on the mainland. 



The continued propagation work with mangoes and avocados has 

 shown that these fruit trees may be easily budded, grafted, or in- 



704S1*— AQR 1912 53 



