. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. ASCOMYCETES 231 On the willow the area occupied by the mycelium sometimes shows a tendency to retain its chlorophyll longer than other por- tions of the leaf. This stimulating effect of a parasite is, however, best marked in the case of Uncinula Aceris (De C.) Wint., occur- ring on several species of maple (Acer). The yellow leaves in the late autumn may show definite green areas, which will be found to be the parts of the leaf occupied by the fungus (Fig. 95). XXX. COMMON MILDEW O
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. ASCOMYCETES 231 On the willow the area occupied by the mycelium sometimes shows a tendency to retain its chlorophyll longer than other por- tions of the leaf. This stimulating effect of a parasite is, however, best marked in the case of Uncinula Aceris (De C.) Wint., occur- ring on several species of maple (Acer). The yellow leaves in the late autumn may show definite green areas, which will be found to be the parts of the leaf occupied by the fungus (Fig. 95). XXX. COMMON MILDEW OF TREES Phyllactinia Corylea (Pers.) Karst. Palla, E. Ueber die Gattung Phyllactinia. Ber. d. deut. bot. Ges. 17: 64- 72. pi. j. 1899. Salmon, E. S. On Certain Structures in Phyllactinia. Journ. Bot. 37: 449- 454. pi. 402. 1899. This species of mildew is so distinct from those previously dis- cussed that it is by some made the type of a sub- family. As previously stated, no haustoria are present, but special seta- like branches penetrate the host. The perithecium is large and provided with hyaline, rigid, acicular ap- pendages, each with a swol- len base. There are many asci, containing 2 or 3 spores (Fig. 86, e). The de- velopment of the asci has been discussed (Fig. 85). This species occurs more commonly upon shrubs or trees, but it is also para- sitic upon a limited num- ber of herbaceous plants. It is known to be distributed throughout the northern hemisphere, and is frequently one of the more common of the surface Fig. 95. Yellow Leaf of Maple, with Green Areas occupied by Uncinula. 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 Duggar, Benjamin M. (Benjamin Minge), 1872-1956. Boston ; New York : Ginn
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