ENEMIES OF THE ROSE 



of the leaf. In the case of black-spot the mycelium is within 

 the leaf. At various points the mycehal threads of the mildew 

 fungus are attached to the surface of the plant by minute 

 branches or suckers which are sent into the outer cells of the 

 leaf or stem from which the fungus obtains its nourishment." 



When the fungus has matured, as it does quickly, these 

 chains of egg-shaped spores are easily carried by the shghtest 

 currents of air to other leaves and thus the trouble spreads — 

 unless we check it, and that, as in many another case, is easier 

 done if "nipped in the bud" because other^vise another spore 

 form soon develops which persists more tenaciously and is more 

 difficult to dislodge. Prof. Massey tells us that sometimes 

 winter spores are produced which "can hve over winter out- 

 doors and may serve to start trouble in the spring." 



"Another source of inoculum for roses in the open is the 

 distribution of the summer spores — formed throughout the 

 year on the roses under glass." These plants in turn are planted 

 out and then these spores may be carried considerable distances 

 by wind, rain, birds, insects, and other agents, and under proper 

 conditions of temperature, moisture, and position, germinate 

 and produce infection. 



Remedies are various,* but probably the most effective and 

 easily apphed and least unsightly is a ground dust mixture 

 consisting of 90 parts sulphur and 10 parts of arsenate of lead. 

 Use a dust gun, and apply upon the first appearance, preferably 

 to all your roses. A week later repeat the dose, and, if necessary, 

 a third time. Then watch out against future recurrence. 

 Powdery mildew can be eradicated after it appears if you attack 

 it properly. 



Black-spot attacks the fohage in the late spring or the summer 

 not only making it unsightly but actually defohating the 

 plants and often seriously checking both growth and bloom. 



Many rose-gardens prove, however, that black-spot can be 

 controlled if one proceeds in earnest. You will recognize irregu- 

 lar circular black splotches on the surface of the leaves which 

 soon after begin to turn yellow and drop off. Cool nights and 

 heavy dews favor its development. 



*Many other formulas are good. See 1922 "American Rose Annual," page — . Also 

 "Enemies of the Rose," by George Massee and F. V. Theobold, 1910, National Rose So- 

 ciety of England. 



