. Bulletin - Massachusetts Agricultural Experiment Station. Agriculture -- Massachusetts. Fig. 2. The street in figure 1, as it would appear without elms. 64,468 known diseased elms have been destroyed programs to September 1942. in eradication. Fig. 3. Elm affected with Dutch Elm Disease. Fig. 4. Streaking of infected wood. Fig. 5. The fungus in culture. Fig. 6. A. Smaller European bark beetle. B. Native bark beetle. C. Larva or grub. (All great'.y en'areed.) Fig. 7. Work of carrier beetles. (Somewhat rediced.) Fig. 8. Natural graft of elm roots. (Photographs from Mass. Exp. hta. Bui. 343. Fi
. Bulletin - Massachusetts Agricultural Experiment Station. Agriculture -- Massachusetts. Fig. 2. The street in figure 1, as it would appear without elms. 64,468 known diseased elms have been destroyed programs to September 1942. in eradication. Fig. 3. Elm affected with Dutch Elm Disease. Fig. 4. Streaking of infected wood. Fig. 5. The fungus in culture. Fig. 6. A. Smaller European bark beetle. B. Native bark beetle. C. Larva or grub. (All great'.y en'areed.) Fig. 7. Work of carrier beetles. (Somewhat rediced.) Fig. 8. Natural graft of elm roots. (Photographs from Mass. Exp. hta. Bui. 343. Figs. 3 and 8 furnished by Division of Forest Pathology. U S D A. Fig. 6 from Cornell Ext.' Bui. 290.) Symptoms of the disease include: Wilting, curling, yellowing, and early falling of leaves; Brown streaking of infected wood. Trees may die suddenly or grad- ually. A wood-staining fungus living in the water-conducting channels causes the disease. Death of trees results from a toxin produced by the fungus. Trees affected with Dutch Elm* Disease may appear similar to elms affected with other wilt diseases— Therefore, laboratory study of wood showing streaking is necessary to prove which dis- ease fungus is present. The smaller European and native elm bark beetles serve as car- riers of the fungus. The beetles engrave breeding galleries in weakened trees and later the young emerge to feed on tender green twigs. Other means of spread include direct contact between diseased and healthy trees — natural grafts of roots and branches. All known diseased elms are being destroyed. The final goal of the eradication program is the protection and preservation of disease-free elms. The public is urged to cooperate by sending specimens from the wilted parts of trees to —. 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
Size: 1468px × 1702px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthormassachusettsagricult, bookcentury1900, bookdecade1900
