ASYIVIMETRICA-VELUTINA 391 



pect, most of these studies have centered upon ways and means of reducing 

 or preventing this rot. As early as 1908, Powell, et al., in the U. S. De- 

 partment of Agriculture, showed that the mold, while always present in 

 citrus producing areas and hence common on the mature fruit, entered as 

 a wound parasite and was unable to penetrate sound fruit. The importance 

 of careful handling in harvesting, storage, and marketing the fruit was 

 recognized and the system of distribution was altered to effect great reduc- 

 tions in losses due to green rot. Subsequent to this Shiver, Fulton, and 

 Bowman (also of the Department of Agriculture) demonstrated that losses 

 could be further reduced by washing the fruit in boric acid or borax solu- 

 tions. The practice has been widety adopted in this country and abroad. 

 Nattrass (1935), working in Cyprus, reported fruits dipped in cold satu- 

 rated borax solution or in 1 per cent "shirlan" (cold) to remain almost free 

 of infection. Tzereteli and Tchanturia (1939) found an 8 per cent solution 

 of borax to give good control in the Georgian Soviet Republic. Tompkins 

 and Trout (1932), in laboratory experiments, successfully reduced losses by 

 storing fruit in air containing low concentrations of acetaldehyde or am- 

 monia. An ammonia concentration sufficient to prevent mold growth was 

 developed by the dissociation of ammonium bicarbonate crystals. Nat- 

 trass (1935) and Tchanturia and Tzereteli (1940) have suggested the use of 

 iodine preparations to combat P. digitatum and P. ilalicum infections. 

 Childs and Siegler (1946) used thiourea and thioacetamide in 5 per cent 

 aqueous solutions and quinosol in 8 per cent solutions for momentary dips. 

 Losses in some varieties were reduced from 40 per cent to 2 per cent or lower. 

 Gioelli (1932) reported marked differences in susceptibility of fruits pro- 

 duced on plots receiving different fertilizers. Fruit from areas receiving 

 potash only or iron sulfate rotted less rapidly than those from plots receiving 

 nitrogenous fertilizers. 



Fulton (1929) investigated the effect of ultraviolet radiations on 27 

 species of fungi, including Penicillium digitatum. An exposure of five 

 seconds at 6 inches killed 907 out of 1000, whereas an exposure of 45 seconds 

 killed 998 out of 1000 spores of this species when spread on the surface of 

 agar plates. Spores on the surface of citrus fruits were likewise killed with- 

 out apparent injury to the fmit. Decay of inoculated fruits was only 

 moderately reduced by exposure to ultraviolet, however, since the light 

 could not kill spores in areas accidentally shaded or penetrate the rind to 

 destroy mycelium already beginning to grow. 



Exposure to ethylene gas has, for a considerable time, been Iviiown to 

 hasten the coloring process in citrus fruits (Denny, 1924). Further, it was 

 commonly observed that the fruit in a crate containing scattered fruits 

 rotting with green mold appeared to "ripen" faster than in like crates con- 

 taining only sound fruit. It was not until 1940, however, that Biale (Univ. 



