. Minnesota plant diseases. Plant diseases. 370 Minnesota Plant Diseases. Later in the year the winter spores are formed in the usual way for the downy mildews, i. e., from breeding organs. The winter spore has a thick coat and remains in the leaf after the latter falls. In the spring the decay of the leaf sets the spore free, and in moist conditions it produces numerous swimming spores; the infection of the vines follows in the usual way. The destruction of fallen leaves, to avoid future infection, is therefore seen to be of im- Fig. 198. Downy mildew of grape. A. Section of a leaf
. Minnesota plant diseases. Plant diseases. 370 Minnesota Plant Diseases. Later in the year the winter spores are formed in the usual way for the downy mildews, i. e., from breeding organs. The winter spore has a thick coat and remains in the leaf after the latter falls. In the spring the decay of the leaf sets the spore free, and in moist conditions it produces numerous swimming spores; the infection of the vines follows in the usual way. The destruction of fallen leaves, to avoid future infection, is therefore seen to be of im- Fig. 198. Downy mildew of grape. A. Section of a leaf with spore-bearing threads emerg- ing from an air-pore. B. Greatly enlarged sucker threads, h. C. Formation of swarm soores in the so-called summer spores; 1, summer spore (is really a spore-case) ; 2, same with protoplasm divided into regular areas; 3, areas of 2 are seen separated, and the whole mass escaping from the spore-case; 4, an escaped and free area of the protoplasm which becomes the swarm spore, 5. D. Formation of egg-spores by the breeding act. Highly magnified. After Millardet. The treatment for black rot is usually recommended for this disease. The sprayings may be at longer intervals. (See Black Rot of Grapes.) Disease-resisting varieties may also be used. It has been rec- ommended that the vine be treated in the fall or early spring, be- fore the buds commence to open, with an iron sulphate Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Freeman, Edward Monroe, 1875-. Saint Paul, Minn.
Size: 1418px × 1762px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectplantdi, bookyear1905
