110 JOURNAL^ OF AGRICULTURE OF P. R. 



the marks occur in great numbers the appearance of the fruit is 

 marred. The cause is difficult to ascertain because of the absence 

 of any fungus-fruiting bodies, and the minute character of the mark- 

 ings, which are probably due, however, to surface infections by some 

 fungus, much after the nature of melanose. The withertip fun- 

 gus is again suspected. 



Leaves may show at times, irregular brown, very slightly raised 

 areas which are caused by gum infiltrations. The initial cause is 

 not certain, but in some instances is due to sun-burning. 



Citrus trees commonly harbor a great variety of mosses, lichens, 

 and other epiphytes (air plants). Several species of orchids and 

 bromeliads grow on the trunks and limbs, as well as a number of 

 ferns. None of the.se plants do any harm to the trees. On the leaves, 

 several simple moss-like plants occur abundantly in shaded and damp 

 parts of the grove, .and may have some slight influence by cutting 

 off light. Circular, silvery .spots due to lichen growth (StrigtiJa 

 sp.) occur in similar situations. 



Various minor fungi, occurring for the most part on dead wood, 

 are recorded in the appendix. The several entomogenous fungi, 

 which might at times, because of tlu-ir al)undaii('(>. come undei' the 

 suspicion of the grower^ are also enumerated and briefly described 

 at the same point. It is desirable that the grower should be famil- 

 iar with these beneficial forms, in order that sucli protection as is 

 possible may be given them. 



BIBLIOGRAPHY. 



The hi-ief list of references given here merely aims to mention 

 such publications as it is thought will be of value to the Porto Rican 

 citrus growers, and which are at the same time easily obtainable. 

 There is, of course, a wide range of other publications on all the 

 various phases of the subject, in large part technical, the substance 

 of which, however, will be found in the ones listed. 



Citrus fruits and their culture. Hume. Published by Orange-.Tudd Co., New 



York. 

 Citrus fruits. Coit. Published by McMillan, New' York. 

 California citrus culture. Cooke. l*ul)lishod by Calif onii;i State Cnnmiission of 



Horticulture, Sacramento. 

 Citrus scab in Porto Rico. Bui. 17, Insular Experiment Station. 

 The handling of Porto Rican oranges, grapefruit, inn! pincMpjilos. Rul. 7, Tnan- 



lar Experiment Station. 

 Scale insects and their control. Circular 9, Insular Experiment Station. 

 Wood rot of citrus trees. Circular 10, Insular Experiment Station. 



