THE MONTHLY BULLETIN 



CALIFORNIA STATE COMMISSION OF HORTICULTURE 



DEVOTED TO HORTICULTURE IN ITS BROADEST SENSE, WITH SPECIAL 

 REFERENCE TO PLANT DISEASES, INSECT PESTS, AND 

 THEIR CONTROL. 



Sent free to all citizens of the State of California. Offered in exchange for bulletins 

 of the Federal Government and experiment stations, entomological and mycological 

 journals, agricultural and horticultural papers, botanical and other publications of a 

 similar nature. 



A. J. Cook, State Commissioner of Horticulture Censor 



E. J. VosLER, Secretary State Commission of Horticulture Editor 



ASSOCIATE EDITORS. 



Geo. p. Weldon Chief Deputy Commissioner 



Harry S. Smith Superintendent State Insectary 



Frederick Maskew Chief Deputy Quarantine Officer 



Entered as second class matter December 29, 1911, at the post office at Sacramento, 

 California, under the act of July 16, 1894. 



Spotting- of Citrus Fruits. — For a number of years past, especially 

 during moist, cool weather, lemons and sometimes oranges, develop 

 after coming to the packing house peculiar surface spots, usually known 

 as "green spots." These spots may later turn reddish or brownish. In 

 these spots there is merely a slight sinking of the tissue between the oil 

 cells. The grade of the fruit is lowered on account of its appearance, 

 but the keeping quality is usually not seriously injured. These spots 

 do not increase in size after once forming. Mr. J. D. Culbertson, more 

 than a year ago, discovered that typical green spots could be developed 

 by pressing and rolling lemon fruits against boards so as to cause 

 injuries. In December, 1914, he also discovered that the oil from one 

 lemon pressed out upon the uninjured surface of another, produced a 

 sinking of the tissue between the oil cells as in the typical spots. It had 

 been noticed by a number of packing house men previous to this, that 

 whenever a strong odor of lemon oil could be detected at the washer, 

 spotting of this kind was apt to follow. This led to the suspicion that 

 the oil might have something to do with the injury. 



In February of this year, I began some experiments in pressing oil 

 from the rind of one lemon onto the uninjured rind of others in jars. 

 When these were picked green, it was found that a very small amount 

 of lemon oil was sufficient to cause in a few hours the sinking of the 

 tissue between the oil cells, which would in time develop the typical 

 green spotting. Other fruits on which no oil was pressed when put in 

 jars developed no spots. Green spots were also brought about by pres- 

 sufficient to cause a visible break in the rind, 

 sure on the surface of the rind sufficient to liberate the oil, but not 



It had also been noticed that green fruits picked while wet or while 

 covered with dew in the early morning were more apt to develop spots 

 than those picked the same day when dry. This may possibly be 

 explained by the result of my experiments with oil on fruit in moist 



