JAMAICA. 



J3 U L Tj K T 1 N 



OF TIIF, 



DEPARTMENT OF AGRICULTURE. 



Vol. II. MAY, 1901. Part 5. 



CITRUS FRUIT CULTURE. II.* 



By J. W. Mills, with notes by Prof. E. W. Hilgard. 

 Notes on Diseases of the Orange. 



Three diseases of the orange tree are widely known in California. 

 First in importance come two kinds of " gummosis," or " gum disease/' 

 that which attacks roots and trunks just above the surface of the 

 ground, and second, that which is called " scaly bark" gum disease. 

 The former has existed in Southern California since 1875. Tt makes 

 its appearance where the ground has been allowed to remain wet close 

 to the trees for long periods. E. W Holm' s, of Riverside, says that 

 he has seen fifteen ^ er cent, of a seedling orat ge orchard become affec- 

 ted after heavy applications of nitrogenous manures followed by irriga- 

 tion close to the trees during hot weather. All the affected parts 

 should be cut out so as to remove every trace of diseased tissue In 

 some cases this requii-es repeated cuttings and the use of an antiseptic 

 wash. 



The " scaly bark" gum disease is the most prevalent form in souih- 

 ern California. It attacks the trunk of the tree, and also some of the 

 branches. If not checked at once, it will kill the tree. The new bark 

 is unhealthy, and the disease soon penetrates to the centre of the limb 

 or the trunk of the tree. 



Antiseptic Washes for Gummosis. — The treatment for both forms of 

 gum disease is the same. Use one part of crude carbolic acid, to four 

 parts of wuter. The Florida Experiment Station uses a wash of lime, 

 crude carbolic acid, and salt. Slack one peck of lime in two gallons 

 of water, and add, of crude carbolic acid four ounces, and of salt three 

 pounds. If too thick, add a little more water. 



In cases of the root form of gummosis, the soil should not be thrown 

 back upon the roots after cutting out the diseased tissue, until the 



*Univer8lty of California, Agricultural Experiment Station, Bulletin No. 138. 

 Continued from Bulletin of Juno & July 1903, page 168. 



