Fern Diseases 259 



spot are found minute black pimples, which are 

 really the pycnidia or fruiting sacs of the fungus. 



The Organism. Fhyllosticta pteridis was first de- 

 scribed by Halsted* in 1893. Since that time the 

 fungus has received no further attention from plant 

 pathologists, hence little is known of its life history. 

 It is probable that spraying with Bordeaux mixture 

 will protect the healthy foliage. 



Algje Parasites on Ferns 



Caused by species of Oscillatoria. 



In damp houses and overwatered soils, the pro- 

 thalia of ferns are often overrun by certain algse 

 which chokes them. This is accomplished by shut- 

 ting out the air and light, interfering with their 

 development and causing them to be completely 

 sterile. As a result, many of the prothalia die. 

 As a control measure, soil sterilization is recom- 

 mended, see pp. 32-43. 



Gardenia {Gardenia jasminoidesyj 



Cultural Considerations. Gardenias are very sen- 

 sitive and easily injured if the temperature falls too 

 low during cold nights. By the end of August, it is 

 advisable to maintain some heat at night so that 

 the temperature may be maintained at about 65 

 degrees F. The plants require an abundance of 

 ventilation. However, the ventilators should be 



•Halsted, B. D, New Jersey Agr. Expt. Sta., Fourteenth Ann. 

 Rept.: 420-421, 1893. 



