172 The Plant World. 



Neither one had any eflfect when they were used to inoculate 

 apples. 



Alternaria sp. — In the genus Alternaria we have a great 

 variation in food habit. Some are parasitic, some saprophytic, 

 and some facultative parasites or saprophytes. 



Alternaria is one of the forms which has been found to 

 cause a rot* and leaf spotf of apples. This form has been 

 worked upon at the Station this year but did not appear in the 

 trap cultures. The two forms which did appear differed from 

 this Alternaria in cultural characters ond food habit. No. 1 

 forms a thin, brown colony which lies close to the medium. 

 No. 2 forms a gray, loose colony. 



To get something of the habits of these two form.s of Alter- 

 naria, inoculations were made on apples, which had been care- 

 fully sterilized by wiping with absorbent cotton moistened in 

 mercuric chloride solution (1-1000). A small incision was made 

 in the apple by means of a sterile scalpel and the spores trans- 

 ferred to the opening. After ten days the gray Alternaria had 

 formed quite an extended zone of rotten tissue. The other 

 Alternaria was not able to produce a rot. 



Oospora sp. — This fungus when it appeared in the plates, 

 formed small, shiny, radiate colonies, which soon became cir- 

 cular, due to the production of numerous spores. It was also 

 used to make inoculations of apples, but it always failed to pro- 

 duce a rotting of the tissues. 



Penicillium expansum Lk. — Penicillium is known to be sapro- 

 phytic and to grow on almost every substratum w^hich contains 

 sugar. It is known to be very destructive among stored apples. 

 No inoculations were made with any other of the fungi which 

 appeared. 



(Continued in August Number.) 



♦Longyear; Bulletin Colorado Experiment Station. 105:1-62. 



fCooper: Alternaria on the Apple — Leaf and Fruit, Thesis, University of Nebraska, 1908. 



