38 



as regularly and as perfectly as any manufacturing establishment 

 turns out its wares. The most important diseases of the rose are 

 as follows : — 



Powdery Mildeio (^SplKerotheca pannosa^ (Wallr.) Lev.). 

 This occurs as a white powdery mass on the upper surface of 

 the leaves, causing them to curl and become distorted. The most 

 skilled growers, however, succeed, as a rule, in handling the con- 

 ditions of the house so intelligently that the mildew is prevented. 

 In case it becomes troublesome through lack of uncontrollable con- 

 ditions, the standard remedy to apply, and one which is very 

 effectual, consists in evaporating sulphur over a lamp. A more 

 practical, as well as a more efficient method of applying sulphur, 

 is to repeatedly paint the pipes with a mixture of sulphur and oil. 



Black Spot (Actinonema Bosce, (Lib.) Fr.). 



Black spot occurs on 

 tlie leaves, causing them 

 to turn more or less yel- 

 low and resulting in their 

 falling off (see Fig. 9). 

 Certain spraying mixtures 

 have been recommended 

 for black spot, but the 

 most satisfactory method 

 of treatment is to keep 

 the leaves picked oft" and 



Fig 9. —Black spot of rose. 



avoid a close atmosphere at night and on wet, dull days. 



Bronzing of Hoses. 

 Rose leaves frequently become spotted and turn yellow and 

 drop off without being affected with the black spot fungus. This 

 happens to those leaves near where the stem has been cut, and is a 

 purel}' functional disorder due, apparently, to the starvation of 

 that particular leaf. It resembles somewhat the black spot, and 

 is termed " bronzing." In all probability it is a correlated growth 

 phenomenon resulting from pruning. 



Eel Worms. 

 Rose growers are sometimes troubled with eel worms, and in 

 same instances large losses have resulted (see Fig. 10). In one 

 instance, to our knowledge, a rose establishment which had pro- 



