. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. FUNGI IMPERFECTI 357 Control. It appears that the only practical methods of prevent- ing this disease are to obtain healthy plants at the outset, to avoid planting where raspberries or other related plants have grown, and to remove and burn old canes as promptly as possible. The results with spraying have not thus far been successful. XLVIII. ROSE LEAF BLOTCH Actinonema Rosa (Lib.) Fr. Cobb, N. A. Black Spot of the Rose. Dept. Agl. N. S. Wales. Miscel. Publ. (2d Ser.) 6661 2-27. //
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. FUNGI IMPERFECTI 357 Control. It appears that the only practical methods of prevent- ing this disease are to obtain healthy plants at the outset, to avoid planting where raspberries or other related plants have grown, and to remove and burn old canes as promptly as possible. The results with spraying have not thus far been successful. XLVIII. ROSE LEAF BLOTCH Actinonema Rosa (Lib.) Fr. Cobb, N. A. Black Spot of the Rose. Dept. Agl. N. S. Wales. Miscel. Publ. (2d Ser.) 6661 2-27. ///. 1904. Scribner, F. L. Black Spot of Rose Leaves. U. S. Dept. Agl. Rept. (1887): 366-368. pis. 8, 9. The rose leaf blotch, or spot, is perhaps the most common and injurious rose fungus aside from the powdery mildew (p. 224). This disease is characterized by more or less irregular brown spots, fairly well defined, on the upper sur- faces of the leaves (Fig. 175), varying from a few millimeters in diameter to areas covering more than one half the entire leaflet. In this darkened area there are distributed a small number of pyc- nidia, producing numerous, ellip- tical, two-celled, hyaline conidia. This spot may be controlled by the use of any standard copper spray, but it is not, of course, de- sirable to spray for a few weeks preceding the blossoming period. Control measures should there- fore look to preventing the dis- ease from securing a start previous to the blossoming season. There is considerable difference in the susceptibility of the dif- ferent host varieties. As a rule the bushy sorts are more severely injured and the climbing roses are often immune. If cuttings are selected from healthy plants, even susceptible varieties may be generally propagated with little fear of serious Fig. 175. Leaf Blotch of Rose. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance o
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