4' BULLETIN 531, U. S. DEPARTMENT OF AGRICULTURE. 



refrigeration can not be transported to distant markets without loss. 

 Although berries may be in the best of condition when picked, they 

 often decay before reaching the consumer, owing largely to the ac- 

 tivity of rot-producing organisms. 



FUNGI. 



Bacterial rots are rare in strawberries. This may be due to the 

 high acid content of the fruit. On the other hand, ripe strawberries, 

 especially if injured, furnish a favorable substratum for the growth 

 of man} 7 ' fungi. Among the less important fungi found were species 

 of Alternaria, Botrytis, Cladosporium, Dematium, Fusarium, Mucor, 

 Patellina, and Penicillium. All these fungi will grow on strawberry 

 tissue, and under unusually favorable conditions some of them may 

 cause appreciable damage. 



Botrytis, long known to occur commonly on strawberries and fre- 

 quently found in fruit from some sections, is not of first importance 

 as a cause of decay in transit. Berries affected by Botrytis in the 

 field are recognized readily and should be thrown out as culls. The 

 growth of Botrytis in the ripe strawberry is so slow that but 'little 

 damage occurs in the short time between picking and marketing. 



Penicillium, which occurs frequently in small quantity, has been 

 abundant in only one case which has come under the observation of 

 the writers. In a shipment from Florida in the spring of 1916 in 

 which the berries were very soft, owing apparently to the effect of 

 the severe sand storm previously mentioned, Penicillium was very 

 common. It is uncertain whether this was due to the condition of 

 the berries or to some unusual opportunity for infection. 



By far the most important cause of rot of strawberries in transit 

 is a species of Rhizopus. Not only is this fungus the most common 

 one on strawberries from every section studied by the writers, but in 

 some instances it is almost the only fungus present. During the 

 spring of 1916 the writers examined more than 14,000 decayed straw- 

 berries shipped on various dates from three localities in Florida. 

 Most of these were kept until quite rotten, and more than 90 per cent 

 of them developed only Rhizopus. 



In addition, several hundred inoculations on strawberries of various 

 varieties have been made, and in no case has Rhizopus failed to pro- 

 duce typical rot when introduced into a Avound (fig. 1). No similar 

 results could be obtained with any of the other fungi found. 



RHIZOPUS NIGRICANS. 



In his recent monograph of the genus Rhizopus, Hanzawa (8) used 

 physiological as well as morphological characters in distinguishing 

 the species. The writers have not investigated the physiology of this 

 fungus sufficiently to compare with Ilanzawa's results, but so far as 



