520 A MANUAL OF THE PENICILLIA 



open lenticels and found severe washing to be especially conducive to 

 infection. A period of pre-storage before washing was found beneficial. 

 Kung-Hsiang (1942) demonstrated that the blushed side of apples was less 

 susceptible to infection than the green side ; increased resistance was thought 

 to result from the greater amount of pectic substances present in blushed 

 areas. Barnum (1922) suggested that PenicilUum reached the tissue of the 

 apple only after entering the cut end of the stem and growing through its 

 full length. This has not been confirmed by other w^orkers. 

 ^; PenicilUum expansum occurs less frequently as a cause of rot in other 

 mature fruits. Ciferri in Italy (1924) described P. malivorum from quinces 

 in terms which leave no doubt as to its close relationship to P. expansum, 

 whatever its minor differences. English (1940) reported it as a cause of 

 decay of pears in Washington. Christoff and Christova (1939) reported 

 P. expansum from quinces, pears, and apples in Bulgaria. English and 

 Gerhardt (1942) found P. expansum as a cause of decay in sweet (Bing) 

 cherries, and concluded that it could be effectively controlled by exposure 

 to practicable concentrations of CO2. The same authors (1946) attempted 

 unsuccessfully to control blue-mold on cherries by means of ultra-violet 

 irradiation. Thom (1930) reported P. expansum in its coremiform phase 

 to be the usual type of Penicillium-rot occurring upon grapes in storage. 

 Investigations involving similar observations have been made in other 

 countries. Mathieu (1924) reported blue and green Penicillia on grapes in 

 France. Not only was the flavor of the grape pulp affected adversely 

 by the mold, but also that of the must made from the moldy grapes. Agui- 

 lera (1926), in Spain, found grapes already packed in barrels to become 

 spoiled by PenicilUum "glaucum" which attacked the stalks and fruit. 

 PenicilUum nearly always produced the first signs of rot. 



It is safe to assume that PenicilUum expansum occurs wherever apples 

 and other non-citrus fruits are grown and held in storage, even for limited 

 periods. 



Anslow, Raistrick, and Smith (1943) reported the production of the anti- 

 biotic patulin by PenicilUum expansum as well as P. patuUmi, the previ- 

 ously reported source (see p. 537). The antibiotic was found to completely 

 inhibit the growth of various "damping-off" fungi belonging to the genus 

 Pythium at concentrations of 1:400- to 500,000, and its possible use in 

 combating such pathogens was discussed. Prior to this, van Luijk (1938) 

 in Holland, had demonstrated the production of substances inhibitory to 

 Pythium by unidentified Penicillia isolated from vegetable mold. Appar- 

 ently these Penicillia found their way into Professor Westerdijk's collection 

 where they were correctly identified, since we received two strains of P. 

 expansum marked "v. Luijk a" and "v. Luijk (3," respectively, from Baarn 

 in 1946. In all probability van Luijk's inhibitory substance represented 



