90 SEVENTEENTH REPORT. 



spots may cause a cracking of the flesh or the cucumbers may be 

 guailed and deforaied. 



Ou the 3'oung fruit the iufection seems to occur principally at 

 the blossom end, there often being a number of spots at this point. 

 This fact may be due to the blossom holding drops of moisture at 

 this end of the fruit and thus allowing more chance of infection. 



In the field the fungus will produce typical lesions in from two 

 to three days under favorable weather conditions, i. e. heat and 

 moisture. It was found by experiment that many of the spots 

 which were unnoticeable at the time of picking would develop after 

 the fruit had been in the crate for 24 hours, since the mass of 

 pickles generates a certain amount of heat and moisture, thus 

 furthering the growth of any fungus present. This fact explains 

 some of the difficulty exix'rienced in trying to cull out all infected 

 fiiiits from diseased fields. 



On the stem the lesions appear first as a slight crack at the sur- 

 face, accompanied by a gradual splitting if growth is rapid. These 

 lesions often attain a length of from .5-1 cm. but are usually onlv 

 from 4-6 mm. long. They occasionally extend rather deeply into 

 the stem and may cause it to break off but ordinarily the injury 

 is superficial. The surface of the spot is not densely covered with 

 spores as it is in the fruit but has more of a brownish, roughened 

 appearance. Spores are present together with the conidiophores 

 but do not produce a dense felt as on the fruit. 



The character of the disease on the petioles is exactly similar to 

 that on the stem. In both cases the lesions are slower to develop 

 than on the fruit, a iJeriod of 5 to 7 days being required before 

 typical lesions occur under ordinary conditions. 



On the leaves the fungus is not so conspicuous as on the other 

 parts of the plant. It appears as a brown translucent spot which 

 tears out very easily. 



DESCRIPTION OF THE FUNGUS, 



The causal organism, Cladosporiinii cucumeriinnii. was isolated 

 from diseased fruits sent to the writer from Big Kapids. Inocu- 

 lations into healthy cucumbers produced typical lesions in about 

 five days, and from these the fungus was reisolated, thus proving 

 its pathogenicity. 



It consists of a much branched, closely septate, granular my- 

 celium, which is occasionally enlarged and swollen so that the seg- 

 ments appear nearly globular. This last character is murli more 

 common on certain culture media tlian on the ])lan(. 



