Frederick A. Wolf

Morphology of Polythrincium, Causing Sooty Blotch of Clover

In 1910, the writer first attempted to isolate the fungus that causes the sooty blotch disease of clover, but was unsuccessful. Repeated attempts have been made, without success, in subsequent years. Apparently similar failures have rewarded the efforts of all other investigators, among whom are Killian (5), BaylissElliott and Stanfield (1), and Horsfall (3), who have studied this fungus. It has been necessary, because this organism is so refractory in this regard, to confine the study of its morphology and development to such phases as could be ascertained from ob? servations made in the field and from microscopic examinations of material collected at intervals throughout the year. The fmd? ings that have resulted are not in accord, in certain features, with those of others, and are herein recorded as a contribution to a better understanding of the structure of this unusual fungus.

Mechanism of Apothecial Opening and Ascospore Expulsion by the Cup-Fungus Urnula Craterium

SummaryThe apothecial wall of the cup-fungus Urnula craterium consists of three layers, an outer black, non-elastic, leathery one, a nearly colorless, gelatinous, water-holding, medullary one, and ...

The Cup Fungus, Ciboria Carunculoides, Pathogenic on Mulberry Fruits

A developmental study has been made of a disc fungus that attacks the fruits of Morus alba. From the results obtained, the organism is transferred from Sclerotinia to Ciborio, and is assigned the b...

A study of Botryosphaeria ribis on Willow.

Botryosphaeria Ribis was first described in 1911 by Grossenbacher and Duggar (2) as the cause of cane blight of species of Ribes. This fungus was not reported to attack other species of plants until 1924, when it was collected on Aesculus hippocastaneunm L. and Rosa setipoda Hemsl. and Nils. (8). Subsequent investigations by Shear, Stevens, and Wilcox (6), Stevens (10), Stevens and Shear (9), Reichert and Hellinger (4), Savastano (5), and Smith (7) have extended the host range to include woody species in nearly a score of families and have shown that the organism has a wide geographic distribution. Although Shear 1 in 1916 collected B. Ribis on willow at Arlington, Virginia, the first account of its occurrence on the genus Salix is that of Stevens (10), in 1924, from collections made in four localities in Florida. B. Ribis has subsequently been collected on pussy willow, Salix discolor Muhl., in Arkansas, Georgia, Mississippi, North Carolina and Virginia. Although the organism is apparently widely prevalent on species of Salix throughout the southeastern United States no studies have as yet been made of the morphology and development of B. Ribis in connection with willow canker.

Production, in Venezuela, of indigenous varieties of tobacco

These varieties, still cultivated in a primitive manner, may have value for hybridizing with Burley and Virginia tobaccos. In Venezuela the leaves are manufactured into cigars or are extracted to produce the masticatories known as “chimo” and “tobacco rope”.

Fungus Spores in East African Lake Sediments. V.

WOLF, FREDERICK A. (Duke Uniiversity, Durham, N.C.). Funigus spores in East African lake sediments. VII. Bull. Torrey Bot. Club. 94: 480-486. 1967.-This study iiivolves the colitent of fungal spores in a 7.78 mneter long core of sediiment taken from Lake Chishi, a Zambian rift lake. This lake is elitirely surrounded by swaamp anld aii abunidant growth of papyrus wvidely occupies its border. The oldest portion of the deposit has an age in excess of 38,000 years. The kilnds of spores founld at each level are illustrated. The population of spores is sparse at all depths. A few kinds occur at widely separated levels aiid are absenit at interveniiig levels. Whether Caesalpiinaceous species and papyrus served as hosts for any of these funigi remains uniklnown. The sediment deposited durinig the past few thousanid years has a large orgaiiic matter coiiteiit that probably was contributed largely by papyrus aind Botryococcus. Factors that appear to be casually related to preservation of spores in sedimeiit, such as organic matter contenit, minieral mnatter content, oxidation, anid chemieal niature of the spore walls are briefly discussed.

The perfect stage of Cercospora sórdida.

Throughout the southeastern United States the foliage of trumpet creeper, Tecoma radicans (L.) Juss., is commonly attacked by the imperfect fungus Cercospora sordida Sacc. This organism was first known to mycologists about 1880, from collections made in Georgia by H. W. Ravenel, who sent specimens to P. A. Saccardo for identification. He, in turn, described it in Michelia, in 1880, and illustrated it the following year in Fungi italici. Subsequently this fungus is listed from collections in New Jersey by J. B. Ellis (Ellis and Everhart, 1885), in Alabama, by G. F. Atkinson (1891), and in Texas, by F. D. Heald and F. A. Wolf (1912), and is among their exsiccati. These facts and other pertinent information on Cercospora are contained in the comprehensive accounts of Solheim (1929) and Lieneman (1929). The present studies, extending over a period of years, are herein recorded as a part of series of observations by the writer on the life history and development of imperfect fungi having perithecial stages that are initiated by spermatia and ascogonia. Some of these observations, involving species of Cercosporella, Lecanosticta, Marssonia, Polythrincium, Ram.ularia, Septocylindrium, Septoria, and Cercospora, have already been published, but a considerable number of others, as yet unpublished, clearly establish that spermatia and ascogonia are precursors of the ascogenous stage.

Cercospora leafspot of Red Bud.

One of the most conspicuous diseases of red bud, Cercis canadensis L., within the area comprising the Duke Forest, is a leaf spot whose cause is commonly designated Cercospora cercidicola Ellis. It appears from the records of collections that this fungus is coextensive in range throughout the eastern United States with that of its host. The writers interest in this disease has centered, for several years, in the developmental morphology of the pathogen. It has been found that the fungus possesses not only a conidial stage but also an ascigerous stage. The former may be found on living leaves throughout the entire period from April to October, and the latter matures in March on decaying leaves, beginning its development, however, during the preceding autumn, with the formation of spermatia and carpogonia.

Two Unusual Conidial Fungi

It occasionally happens, during the routine of collecting and identifying fungi, that a species having an unusual type of conidium and conidiophore is encountered. The two species given brief consideration herein are believed to be quite unlike any with which even well-trained and experienced students of fungi are acquainted, and consequently they are worthy of mention. One of them has been identified as Cephaliophora tropica Thaxter, and the other, as an hitherto undescribed species to which is given the name Ypsilonia corticalis.

Life Histories of two Leaf-Inhabiting Fungi on Sycamore

Leaf and twig blight of sycamore, Platanus occidentalis L., caused by Gnomonia veneta (Sacc. & Speg.) Kleb. is a widely prevalent disease. For a number of years it was assumed that this disease was the most common malady involving sycamore within the Duke Forest. During the past three years, however, my observations have indicated that this disease has been confused with another leaf blight disease, mainly caused by Stigmina Platani (Fuckel) Sacc., that is locally of considerably more consequence. Whilst studying this Stigmina disease it became apparent furthermore that the Stigmina leaf blight fungus is commonly associated with another pathogen, Cercospora platanifolia Ellis & Ev. Both StigmlinaF Platani and Cercospora platanifolia have long been known to mycologists, but as a result of the present study each has been found to possess a perithecial stage that matures in spring on decaying infected leaves. The life histories of these associated leaf-inhabiting fungi are therefore recorded at this time as a contribution to our knowledge of the diseases of sycamore. Appearance of the Disease Complex.--Lesions induced by Cerospora platanifolia are first noted about mid-June, those by Stigmina Platani toward the close of July. In the case of the former very irregular, minute, brown, necrotic spots develop (FIG. 14). They are sparse at first and about 1 mrm. in diameter, but eventually several hundred lesions may appear on a single leaf. At this stage many of the spots will have fused. Infection by Stigmina is first apparent by the presence of scattered, pale-green areas, if affected leaves are viewed from the upper leaf surface, the lower leaf surface of the corresponding areas being covered with a thin, weft-like, black coating (FIG. 14).