146 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



commercial quantities appears to be assured. The cotton plant 

 recjuires less water than sugar cane, and already over 500 acres of 

 cotton have been planted on sugar plantations where irrigation water 

 was deficient. Sea Island and Caravonica varieties are the chief 

 ones used, and their cultivation as perennials is intended. By 

 pruning at the proper season the time of picking can be made to 

 articulate very well with the cane-grinding season, when there is the 

 greatest demand for labor on the plantations. The adaptability of 

 this crop to the owner of a small tract of land is being demonstrated. 

 Breeding experiments with cotton are being continued, and by 

 vegetative propagation some desirable strains are being rapidly 

 developed, without the possibility of undesirable crosses through 

 poUination. The investigations on rice have resulted in some new 

 varieties produced by breeding experiments that exceed any in 

 common use. They have also shown the value of ammonium sul- 

 phate as a fertiUzer for the rice crop. The visit of the agronomist 

 to Japan last season resulted in the introduction of a number of 

 newly-developed varieties of rice, some of which appear very promis- 

 ing. The pineapple soil studies have been continued, and it has 

 been found that where the manganese content is not too high the 

 use of suitable fertihzers will correct the injury due to manganese. 

 A more serious pineapple trouble in Hawaii has been found, due to 

 a lack of aeration of the soil, and studies to correct this condition 

 are in progress. A study of the pineapple fruit has shown the 

 influence of ripeness on the sugar content. There appears to be no 

 increase in the amount of sugar in a fruit after it is cut, although 

 the fruit will become yellow and soft, hence the importance of the 

 stage of maturity on the quality of the fruit. The rubber-tapping 

 experiments have been continued, and the profitableness of growing 

 Ceara rubber has been shown. In connection with the rubber 

 investigations it has been found possible to keep down all weed 

 growth by spraying between the trees with arsenite of soda. A 

 demonstration on 400 acres showed the success of the treatment at 

 the low cost of $1.25 per acre. 



In Porto Rico one of the most striking results of the investigations 

 during the past year was the determination of the cause of the chlorosis 

 in pineapple plants. This rather serious trouble was found to be due 

 to the abundance of calcium carbonate in the soil, and it was found 

 inadvisable to plant pineapples on soils containing more than 5 per 

 cent of calcium carbonate. The work on sick soils, due to super- 

 abundant bacteria, has been continued, and disinfection by chemicals 

 or by frequent deep plowing has proved of value in correcting the 

 trouble. The rapidly developing citrus industry has necessitated 

 much attention to the insect and fungus pests of these crops, and 

 some of the results of the investigations have been issued. The great 



