RHIZOPUS EOT OF STRAWBERRIES IN TRANSIT. H 



arrival in good order. Some of the remainder was held in the car two or three 

 days and part of it at a commission house, and it deteriorated very rapidly. 

 owing to the attacks of Rhizopus nigricans. The fruit leaked badly, many of 

 the peaches becoming completely penetrated and overgrown by the rot fungus. 

 In this case the fungus appeared to grow readily from one fruit to another, 

 possibly through the stem end. 



It is significant that in all cases where the rot caused by Rhizopus 

 nigricans is described it is characterized by the loss of a large quan- 

 tity of liquid from the decaj^ed tissue. Behrens (2) and Wormald 

 (17) speak of this in discussing the rot of tomatoes, Halsted (7) in 

 quince, Orton (11) in potatoes, and Waite in pears and peaches. 



The observations recorded above show that Rhizopus is the chief 

 and in some sections practically the only cause of rot of straw- 

 berries in transit. They show that the percentage of moisture in the 

 air makes no difference in the rate of growth of the fungus inside the 

 berry. Also, that while the growth of Rhizopus is very slow at 10° 

 C. (50° F.) or below, the rate increases rapidly with the rise of tem- 

 perature above that point, so that at favorable temperatures a straw- 

 berry infected with Rhizopus is destroyed in a few hours. Micro- 

 scopic studies by one of the writers (13), as well as inoculation 

 experiments and field observations, indicate that Rhizopus does not 

 usually penetrate the uninjured epidermis of the strawberry. 



From this work it is apparent that no method of drying the air of 

 the container in which the strawberries are shipped, by ventilation 

 or otherwise, will retard the decay of the fruit once the fungus has 

 entered, but that rot of strawberries in transit may be diminished 

 greatly by reducing the amount of infection hy Rhizopus or by keep- 

 ing the berries at a low temperature from the time they are picked 

 until sold. The importance of low temperature in shipping straw- 

 berries was demonstrated by Parker Earle during the period from 

 1866 to 1872 (3 and 4). Earle found that strawberries cooled to 

 50° F. in a specially constructed cooling house previous to shipment 

 might be sent long distances in refrigerator cars in practically perfect 

 condition. 



PRESENT SHIPPING PRACTICES. 1 



To appreciate the general lack of complete refrigeration and the 

 importance of reducing infection by Rhizopus, it is necessary to 

 know something of the methods of handling strawberries now in 

 general use. 



1 Descriptions of the development of refrigerator transportation of truck produce were 

 published in 1901 by F. S. Earle (3) and W. A. Taylor (15). Of particular interest in 

 this connection are the descriptions (3, p. 444 ; 15, p. 575) of the early work of Parker 

 Earle in shipping strawberries under refrigeration. So far as the writers have been able 

 to learn, Parker Earle designed the first refrigerator chest for shipping strawberries by 

 express and was the first to demonstrate the effectiveness of precooling. His letter 

 (3, p. 444—445) places the beginning of this work about 1866, and it was mentioned by 

 Ilolcomb in 1870 (10). 



