CITKTJS CULTURE IX PORTO RICO 



13 



Apparently grapefruit was not used for stock in the island's first 

 nurseries, and perhaps none of the trees of the early introduction 

 from Florida were budded on grapefruit stock. That it soon be- 

 came popular is attested by the fact that many of the grapefruit 

 trees in 20-year-old groves are budded on grapefruit stock. Field 

 studies did not show that grapefruit has been used as a budding 

 stock for orange. 



Some years after grapefruit began to be extensively used as a 

 stock, a few growers started to use the seedling or so-called native 

 grapefruit. No differences could be detected between the trees 

 budded on this and other grapefruit stock in two small groves, 12 to 

 14 years old, which were observed. The growth of the seedling tree 

 indicates that it may prove to be a desirable stock. In addition to 

 having vigor and health, it is immune to scab. Grapefruit when 



Figure 6. — Grapefruit budded on grapefruit stock. Typical 

 bud union. 



budded on grapefruit stock and grown in good soil is characterized 

 by (1) vigorous growth and large size, indistinguishable from trees 

 budded on lemon stock, and (2) a smooth bud union and a trunk 

 which is seldom constricted below the union like the sour orange or 

 enlarged like the lemon. 



As a result of observations made in many groves, it is concluded 

 that the rough lemon may be used as stock for both orange and grape- 

 fruit. It may be planted in any soil that is suitable for citrus grow- 

 ing, and is preferable to other stocks in extremely light sandy and 

 in very impervious soils. The indications are that time of fruiting 

 may be controlled more readily with trees budded on lemon stock 

 than on sour-orange stock. Trees which are budded on lemon stock 

 are said to be more likely to produce coarse fruit than are those 

 budded on the other stocks. This was not found to be the case, but 

 may be in a more extensive study when more fruit is available. The 



