30 



THE MONTHLY BULLETIN. 



Green Spot of Orange. — In the September, 1915, number of The 

 IMonthly Bulletin may be found an article by Professor H. S. FaAvcett, 

 entitled ''Spotting of Citrus Fruits." This article gives the results 

 of experimental work proving that the oil from the rind coming in 

 contact with the surface of the fruit produces the characteristic spot- 

 ting. Recently the subject of spotting has received considerable 

 attention by growers and packers in the Fair Oaks section, who 

 noticed a very general injury to oranges picked early in the season, 

 and there was much speculation as to the cause. 



Some experimental work by Mr. E. J. Vosler and the writer gave 

 exactly the same results as that done by Professor Fawcett. The 

 accompanying illustration shows the result of placing some oil from 



Fig. 14. — Green spot produced on orange by smearing the 

 oil from the peel of another orange on the surface of the 

 fruit when green. (Original.) 



another orange on the surface of a fruit without bruising in the least. 

 This orange, after being treated, was placed on a shelf in the labora- 

 tory and the typical spot developed within twenty-four hours. In 

 this case there was no moisture present exce])t. that of the ordinary 

 steam-heated room. A half dozen fruits treated all developed typical 

 cases. 



It is interesting to note that experiments conducted in a grove at 

 Fair Oaks, to determine the effect of the oil upon oranges before 

 being i)icked, proved that the same injury would result but not to 

 quite so severe a degree. Some fruit treated on the south side of a 

 tree where the oil rapidly evaporated caused no injury, while on the 

 north side several typical cases resulted. 



The fact that injury may occur to fruit on the trees makes it douI)ly 

 advisable to prune in such a way as to avoid all possible bruising of 

 the fruit, before picking, from Avinds, etc., for such bruising may 

 result in the liberation of oil and consequent spotting. — G. P. W. 



