ASYMMETRICA-FASCICULATA 519 



experiments, areas of soft brown rot are quicldy formed (fig. 130B and C) 

 and rapidly extend to involve the whole fruit (fig. 130A). The develop- 

 ment of these areas is usually accompanied by the formation of prominent 

 coremia which subsequently' develop powdery masses of blue-green conidia. 



The organisms responsible for the decay of apples, grapes, and other 

 non-citrus fruits have been studied by many investigators over a period of 

 many years. Wehmer (1895) discussed, as Penicillium glaucum, coremi- 

 form structures occurring upon apples and grapes in Hannover. Eustace 

 (1908) studied the apple-rot fungus as it occurred upon fruit in storage in 

 New York. Brooks, et. al. (1920), Fisher (1922), and others in the U. S. 

 Department of Agriculture, studied the organisms and devised methods 

 for their control. 



Difficulties arising from extended storage and shipment of fniit to East- 

 ern markets and abroad has necessitated thorough investigation of the 

 blue-mold apple rot problem in the Pacific Northwest. Heald and Ruehle 

 (1931) found Penicillium expansum capable of rotting apples twice as fast 

 as any other species and reported it to be responsible for 75 per cent of the 

 losses of Washington apples in storage. Heald (1927), Heald and Baker 

 (1932), and Baker and Heald (1932b) discussed methods of controlling 

 blue-mold, with particular reference to the handling, cleaning, and packing 

 of apples. The same authors showed that sodium hypochlorite was very 

 toxic to conidia of P. expansum, and later (1934) recommended, as a control 

 measure, that apples be dipped in a rinse containing NaOCl (containing 

 0.4 per cent available CI) after the apples had been washed in a HCl cleaner 

 to remove spray residues. Wellman and Heald (1940) investigated the 

 potentialities of many additional chemicals, including several dyes, but 

 made no recommendation for commercial practices. Smock and Watson 

 (1941) and Watson (1943) demonstrated that daily exposures to low con- 

 centrations of ozone in storage areas markedly reduced infection and 

 rotting of apples by P. expansum. 



The mechanism of attack in the destruction of fruit by Penicillium 

 expansum has received considerable attention. Nobecourt (1922) attri- 

 buted the break down of tissue to cytolytic enzymes secreted by the molds, 

 which affords an easy path of entry. Fisher (1922) concluded that P. ex- 

 pansum could not penetrate the uninjured surface of the apple but recog- 

 nized that minute injuries were sufficient to permit invasion. Morse and 

 Lewis (1910), Anderson (1920), and others express similar views, but all 

 agree that sound apples in close contact with rotting fruit can become in- 

 fected without actual wounding. Kidd and Beaumont (1925) and Baker 

 and Heald (1932a) demonstrated that lenticels provide a common route 

 of entry for P. expansum into otherwise sound apples. English, el al. 

 (1946) found that washing procedures generally increased the number of 



