70 HATCH EXPERIMENT STATION. [Jan. 



upon Ficus rcligiosus, the banyan tree, proved to be simply 

 a sun-burn, though its superficial resemblance to the fungous 

 disease was most perfect. Quite a serious and apparently 

 new spot disease of greenhouse orange trees has been met 

 with, which is of true fungous origin. It is not necessary to 

 describe all these forms in detail, as the treatment is practi- 

 cally the same in each case. 



A So-called Black Spot of fJte Rose. 

 (Plilobolus c7'>/staJIi)ii(s, Tode.) 

 It is not unusual to find rose bushes in the greenhouse 

 thickly dotted over with little black specks, appearing not 

 unlike "fly specks," which occur on all parts of the plants 

 alike, and of course greatly disfigures the blossoms. Micro- 

 scopic examination shows each speck to be a minute sac, 

 filled with Avhat are evidently fungous spores. It would 

 thus appear that we had here a fungous disease, and as such 

 it has been described under several different names. In fact, 

 however, this is in no sense a disease, and the little sacs of 

 spores have no real connection with the rose plant, being at- 

 tached to it simply by cohesion. The sacs of spores or 

 sporangia are produced by a fungus, Pilobolus crystallinus, 

 which is strictly sa})ro})hytic, and grows on decaying ma- 

 nure. As such manure is usually placed u})on the soil under 

 roses, spores of the Pilobolus are introduced in it, and find a 

 favorable place for development. They produce the thread- 

 like filaments which make up a fungous plant, and on the 

 ends of certain of them sporangia are developed. The fila- 

 ment behind each sporangium becomes filled with a watery 

 fluid, which gradually increases in quantity, and exerts a pres- 

 sure on the sporangium at the end. This pressure becomes 

 so great that finally the sporangium, at about the time of its 

 maturity, is forced from the end of the filament with sufficient 

 power to send it a considerable distance. We have seen 

 them on the roof of a rose house at least eight or ten feet 

 from the soil where they were produced. Striking a plant, 

 they adhere to it, and give the appearance of having devel- 

 oped there. We find them particularly on the rose, simply 

 because the practice of covering the soil Avith manure is con- 

 fined to the cultivation of that plant. 



