. Minnesota plant diseases. Plant diseases. 278 Minnesota Plant Diseases. of the tree interfered with but the tree is usually stunted and may eventually die. The leaves of the diseased shoots contain less leaf-green and are paler in color than the ordi- nary leaves. The exact method of the infection by spores in this country is not yet known. A similar disease on the silver fir in Europe has recently been thoroughly investigated. It is found that the cluster-cup spores of the silver fir brooms can- not infect the silver iir leaves but can cause infection on certain plants be- longing to the pi
. Minnesota plant diseases. Plant diseases. 278 Minnesota Plant Diseases. of the tree interfered with but the tree is usually stunted and may eventually die. The leaves of the diseased shoots contain less leaf-green and are paler in color than the ordi- nary leaves. The exact method of the infection by spores in this country is not yet known. A similar disease on the silver fir in Europe has recently been thoroughly investigated. It is found that the cluster-cup spores of the silver fir brooms can- not infect the silver iir leaves but can cause infection on certain plants be- longing to the pink family, e. g., the common chick- weeds. Here the fungus gives rise to the summer- and winter-spore stages. From the winter- spore forms infec- tion of the silver fir takes place. The commencement of the characteristic broom-like growth of the branches takes place in the following year. No experiments have yet been carried on to determine wheth- er or not the American fungus on the balsam fir is or is not identical with the European form on the silver fir. All brooms should be removed and burned especially before the formation of the cluster-cup spores in the spring. (See F'ig. 23.) The poplar rust [Melampsora populina (Jacq.) Wint.]. The poplar rust is exceedingly abundant in Minnesota and in some cases probably efifects considerable damage of young poplars. Fig. 137.—Poplar leaf rust (Melampsora populina). A poplar leaf showing the fine, black spots of the crust- like clusters of winter spores on the under surface. 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: 1338px × 1868px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectplantdi, bookyear1905
