34 



using pure sea sand in the germinating bed, which has also been found 

 entire!}" satisfactory here, but the plants should not be transplanted 

 until the wood is well matured. This seedling disease is very destruc- 

 tive and very few volunteer seedlings survive. There are certain 

 places on the island, however, where seedlings are plentiful under the 

 large trees, and there it would probably not be difficult to grow a 

 nursery. 



AVOCADOS. 



The 2-year-old trees in the miscellaneous orchard average 11 feet 

 high with a spread of 7 feet. (PI. IV, fig. 2.) Fifty more have been 

 planted and a nursery containing about 1,000 ])lants has been started. 



RUBBER. 



The condition of the rubber trees is very much as in the last report. 

 The Central American rubber trees (Castilloa elastica) which have 

 been planted three years in very rich soil are now 16 feet high with a 

 spread of 12 feet (PI. V, fig. 1), while the others j^lanted in the usual 

 heavy clay soil are only 4 to 6 feet high. Trees which were sent to 

 Arecibo and Bayamon have made growth similar to the best of these 

 when on cultivated and fertilized soil. Some of the trees in the station 

 plantation have been fertilized with stable manure, without percep- 

 tible change in growth and the result so far is negative. The experi- 

 ments have brought out the following facts which correspond with the 

 experience of the horticulturist in Florida. The Castilloa succeeds best 

 when not transplanted or when transplanted very young, so as not to 

 disturb the roots. A tree six to twelve months old is severel}' stunted 

 by transplanting. The methods of planting in sod and keeping a 

 small circle clean around the trees has not proved successful, except in 

 soil which would have grown any other tropical tree under the same 

 conditions. Hevea hraziliensis has made but slow growth. ManiJiot 

 glaziovii has made a fairly good growth near San Juan, where a few 

 trees are planted in a yard. It is of com-se cultivated and probably 

 fertilized. Small seedlings in the station nursery have been attacked 

 by the cassava bud-maggot, which, however, does not damage larger 



trees. 



MISCELLANEOUS PLANTS. 



The following report does not include all of the plants under experi- 

 ment by the horticultural department. Many have been omitted 

 because it was thought that the conditions imder which they were 

 planted and the care received afterwards were wholly unsuitable. The 

 same may be said about some of those reported upon, because a field 

 test made here can not be taken as a criterion for the whole island. 

 The chief aim of these experiments is to secure data for a report upon 

 plants which may be of economic interest. This will bring them to 



