STATES KELATiOXS SERVICE. 461 



fluence of phospliatic fertilizers on chlorosis. Experiments are in 

 progress in which the eli'ect of lime, leguminous crops, cane residues, 

 and various chemical fertilizers on the nitrogen balance of the soil 

 are being investigated. 



On account of the presence in Porto Rico of the mosaic, or mottling, 

 disease of sugar cane, work with immune or resistant varieties of cane 

 is being emphasized. The station is now growing two varieties that 

 appear to be wholly immune and several others that have such a 

 high degree of resistance that they give large yields in spite of the 

 presence of the disease. These varieties are being propagated as 

 rapidly as possible for distribution to planters. In connection with 

 the production of food crops the work with beans and rice is con- 

 tinuing to receive much attention. A large number of varieties of 

 beans have been tested, and those already acclimated to tropical 

 conditions appear most promising for extended trial. A black bean 

 from Venezuela is giving the best yields, but local prejudice against 

 its color prevents its more extended planting. Some mutants ranging 

 in color from white to purple have been found, and these are being 

 carefully studied to find colors that are accceptable and at the same 

 time prolific in jdeld. The work with rice has been continued, but on 

 a reduced scale, as it was impossible to secure the cooperation of 

 managers of large plantations owing to their interest in sugar-cane 

 growing. Tests of 145 samples of native upland rices were made 

 in the station trial plats, from Avhich it is hoped to develop valuable 

 strains for hillside planting. The station has been active in intro- 

 ducing a number of new crops, and much interest has been aroused 

 in cowpeas, soy beans, mung beans, and improved varieties of chick- 

 peas. Additional cover crops have been tested and Crotalaria juncea, 

 a recent introduction to Porto Kico. gave a yield of 12.6 tons in 10 

 weeks from planting. Napier, or elephant grass, introduced by the 

 station a few years ago, is proving adapted to almost every type of 

 soil and its distribution is proceeding rapidly. 



The investigation of vanilla as a possible new industry is being 

 continued, and the crop of the last season was sold at $3 per pound. 

 Experiments are in progress on methods of curing and preparing for 

 market that appear to indicate a higlier grade of product. The 

 yields obtained suggest conditions under which maximum production 

 may be expected. One large commercial planting of vanilla has 

 been made as a result of the station's investigations and others are 

 contemplated. 



Work with vegetables is being given especial attention at the sta- 

 tion and also on other types of soil in several localities in the island. 

 Success has been met with in the production of a large range of 

 standard vegetables, and improved strains are being more generally 

 planted throughout the island. The work with wilt-resistant toma- 

 toes seems especially promising, and it is hoped that resistant strains 

 of good quality will be available for distribution in the near future. 



A study is being made of the causes contributor^^ to citrus scab, 

 especially the effect of certain fertilizers, cover crops, cultivation, 

 location of groves, etc. A mosquito survey of Mayaguez and vicinity 

 was made in cooperation with the sanitary authorities of the city. 



