HORTICULTURE. 39 



stock rosistanco to "nial de j;oina," effect of stock on scion, pruning, and plant 

 selection and breeding for special purposes. A detailed statement is given of 

 the work being done or planned in the various lines. 



In order to emphasize the former work by the station, experiments are being 

 carried on to determine more definitely the special growth seasons for different 

 classes of vegetables. Some of the points thus far brought out from this work 

 are that such vegetables as radishes and lettuce with proper culture grow well 

 at all times of tlie year, except in periods of excessive rainfall ; that many 

 others do have certain seasons in which they grow best; that these seasons are 

 usually during the early winter and spring months; that the insect i)ests and 

 diseases are, in a large nieasure, periodic; that tomatoes, melons, cucumbers, 

 and some others can be grown in Porto Rico for a winter or spring market ; 

 and that good seed of many classes of vegetables can be home grown and the 

 better native varieties readily improved. 



Among the orchard fruits giving promise of sufficient merit to warrant fur- 

 ther investigations are the Japanese persinunon, the Peen-to peach, the cheri- 

 nioyer, the loquat, and several of the imported guavas. With a view of study- 

 ing in detail cultural methods, diseases, and various other problems of fruit 

 growing, several new plantings have been made, including a new citrus grove 

 and a cacao grove, with rubber for shade, as well as miscellaneous plantings of 

 cocoanuts. 



Notes are given on the work with cocoanuts, rubber, mangoes, bananas, and 

 pineapples, as well as brief notes on several miscellaneous fruits, including the 

 Barbados cherry, Otaheite gooseberry, anona, rose apple, guava, avocado, and 

 cacao. 



A large number of standard varieties of grapes have been introduced and 

 have made an exceptional gi'owth during the year. It is found that heavy 

 pruning can be done without apparent injury while the vine is in full growth. 

 Pruning semidormant vines caused severe bleeding. By 1 or 2 heavy prunings 

 at the proper time and pinching the buds before the growth fairly begins, it is 

 possible to keep the vines in good bearing condition. Several new varieties of 

 strawberries are being tested, some of which have stood the adverse conditions 

 of drought and excessive rains and give promise of producing excellent fruit. 

 The crop is not heavy at any one time, but the bearing period lasts over several 

 months. 



In the cooperative fertilizer experiments, in all the soils thus far tried a com- 

 plete fertilizer has given a marked increase in growth over no fertilizer or one 

 composed of 1 or 2 elements only. In no case has there been less than from 

 10 to 15 per cent gain in favor of a complete fertilizer. No injurious effects 

 have been noticed from using chlorids or organic fertilizers in citrus groves. 

 The " mal de goma " present in some groves seems in almost all cases to be duo 

 to too deep planting, bad drainage, or some allied cause rather than to the 

 ])resence of organic matter. In the station orchard fresh manure has been 

 liberally spread with beneficial results. 



In the work in ])lant improvement, practically all of the standard vegetables 

 are under observation, and all the native strains that give any promise of merit 

 are being tested. Special emphasis is being laid on breeding disease-resistant 

 \ari<>ties. The tomato, eggplant, cucumber, and muskmelon are being given 

 s])ecial attention. Some of the most stubborn diseases, like wilts and mildews, 

 can be overcome by breeding and selection. With choice eggplants grafted on 

 native wild eggplants, the grafts seemed proof against disease and the fruits 

 were large and of excellent quality. The jilants bore several successive crojis 

 and were destroyed only by a newly ai)pearing insect, which did the damage 



53S1S— No. 1—08 i 



