bluuebunny/crossref_metadata_2025 huggingface dataset:
SELFING STUDIES WITH PHYSIOLOGIC RACES OF WHEAT STEM RUST, PUCCINIA GRAMINIS VAR TRITICI
Authors: Johnson T.
Published: August 2008

Forty-two cultures of wheat stem rust (Puccinia graminis var. tritici Erikss. and Henn.), comprising 34 physiologic races, were subjected to selfing studies each of which involved the inoculation of barberry plants with the sporidia of a race, and the determination of the races in the uredial cultures derived from the aeciospores. In all of the cultures studied, the pathogenic properties expressed on the differential hosts appeared to be inherited according to the same principles. On the varieties Marquis and Kota (Triticum vulgare), pathogenicity of the races in the progeny tended to resemble that of the parent race. On Reliance (T. vulgare), avirulence was a dominant character, virulence a recessive one. On the durum wheats Arnautka, Mindum, and Spelmar, virulence was a dominant and avirulence a recessive character. On Einkorn (T. monococcum) and on Vernal (T. dicoccum), avirulence was dominant to virulence. In the progenies of some races, pathogenic variation occurred though it did not transgress the circumscribed limits of the parent race; the population therefore consisted chiefly of substrains (biotypes) of the same race.
PHOSPHORYLASE IN THE CHLOROPLASTS OF WHEAT
Authors: Shaw Michael
Published: August 2008

Phosphorylase activity was demonstrated in the chloroplasts of wheat, bean, and sunflower by incubating living starch-free sections with glucose-1-phosphate in acetate buffer at pH 5.8–6.0.
FRUCTIFICATION OF PORIA COCOS (SCHW.) WOLF ON POPLAR
Authors: Fritz Clara W.
Published: August 2008

The subterranean sclerotia of Porta cocos (Schw.) Wolf have been known in North America for more than one hundred and fifty years, but sporophores of the fungus are rare. This paper reports the First fruit bodies of this fungus found in Canada. They developed on poplar pulpwood bolts during storage; the history of the logs from the time of cutting up to the finding of the sporophores is recorded.
BOG AND LAKE STUDIES ON THE LAURENTIAN SHIELD IN MONT TREMBLANT PARK, QUEBEC
Authors: Potzger J. E. , Courtemanche Albert
Published: August 2008

The study includes five bogs and one small lake. Preferred kettletype bogs were located very effectively by plane. The deepest section of the kettle lake was determined with a Bendix Depth Finder. The initial tree invaders in the whole park were chiefly jack pine (Pinus banksiana), paper birch (Betula papyrifera), a minor representation of spruce–fir (Picea–Abies), and oak (Quercus) characterized by an attention-demanding minor peak. After one or two foot-levels spruce–fir increased to considerable prominence, then declined to negligible representation in all bogs and in the lake by mid-profile. The pine peak at about mid-profile was uniformly very prominent over the whole area. In the topmost one-third to one-fifth of the profiles, pine declined steadily. The small representation of pine at topmost levels pictures very well its status in the region today. Mont Tremblant Park is a forest transition zone. In the range of 50 miles from Lac Puant bog to Lac Tacoma bog, abundance of spruce and fir pollens (especially that of black spruce) increase markedly as one proceeds northward. Pollens of beech (Fagus), oak, maple (Acer), and especially hemlock (Tsuga) and yellow birch (Betula lutea) show marked decrease northward. In the southern half of the transect hemlock is represented in the profiles by a decided pine–hemlock peak. Paper birch has erratic fluctuations in its prominent representation over the whole profile. From the forest type indicated at lowest levels we must infer an initial warm period. This is attributed to ocean invasion of the St. Lawrence Valley and slow retreat of continental glaciers. The combination of these factors delayed the forest invasion of the Canadian Shield until the boreal spruce–fir period, so characteristic of lowest levels in bogs farther south, had passed. Slight deterioration of climate thereafter with development of local glaciers on the Shield apparently accounts for the first minor rise of spruce and fir. A warm–dry period at mid-profiles is indicated by the universal prominent pine peak accompanied by extreme decline of spruce and fir. The succeeding increase in hemlock and white–red pine (later replaced by minor peaks of beech–maple) suggests a monster climate with increasing coolness. Continued cooling during more recent times in turn favored spruce, fir, and yellow birch. Pine, hemlock, beech, and oak declined to a status of minor elements in the forest association. The erratic fluctuations of paper birch and its abundance at all levels show little correlation with major climatic changes.
THE OCCURRENCE OF FUSARIUM SPECIES IN CANADA: IV. TAXONOMY AND PREVALENCE OF FUSARIUM SPECIES IN THE SOIL OF CEREAL PLOTS
Authors: Gordon W. L.
Published: August 2008

A taxonomic study was made of 12,485 isolates of Fusarium that were obtained from a total of 1674 soil samples taken from two series of permanent cereal plots during the years 1936–1942. Isolates of Fusarium averaged approximately 16% of total fungus isolates. A total of 16 species, varieties, and forms of Fusarium, classified in eight sections of the genus, were isolated. These species, varieties, and forms are F. dimerum Penz., F. merismoides Cda., F. poae(Pk.) Wr., F. sporotrichioides Sherb., F. avenaceum (Fr.) Sacc., F. concolor Rg., F. semitectum Berk. & Rav., F. acuminatum Ell. & Ev., F. equiseti (Cda.) Sacc., F. culmorum (W. G. Sm.) Sacc., F. sambucinum var. coeruleum Wr., F. sambucinum f. 6 Wr., F. oxysporum Schlecht, em. Snyder & Hansen, F. oxysporum var. redolens (Wr.) Gordon, F. solani (Mart.) App. & Wr. em. Snyder & Hansen. The majority of the species isolated were encountered each year. F. oxysporum and F. equiseti, together, accounted for approximately 75% of the total Fusarium isolates. Average concentrations per gram of soil of these two species were approximately 4800 and 2300 'units', respectively. Average concentrations per gram of soil of each of the remaining species isolated were below 600 units. Except for F. dimerum and F. merismoides, the species, varieties, and forms that were obtained from soil have been isolated previously from the basal parts and seed of cereals in the Prairie Provinces.
INVESTIGATIONS OF RHIZOCTONIA CROCORUM (PERS.) DC. IN RELATION TO THE VIOLET ROOT ROT OF CARROT
Authors: Whitney N. J.
Published: August 2008

Violet root rot of carrot, caused by Rhizoctonia crocorum (Pers.) DC, appears in Ontario in midsummer, and by the fall progresses to cause deep lesions in the fleshy root of the carrot. Isolation of the fungus from diseased carrot was successful only from mature infection bodies. Of all the media tried meat–malt agar supported the best growth of R. crocorum. While three types of hyphae were produced only those of the subiculum propagated the fungus, and only the subiculum and sclerotia were capable of initiating a parasitic attack on carrots. R. crocorum can infect any part of a carrot root, does not require a wound infection court, and can spread uniformly over the carrot regardless of where primary infection occurs. Although the development of the carrot, the growth of R. crocorum, and the incidence of infection reached a maximum within the pH range of from 5.5 to 6.5, both host and fungus tolerate, and infection occurs within, a much wider pH range. The cardinal temperatures for infection were 5°, 20°, and 30 °C., and there was a close correlation between the temperatures for best growth of the fungus and the host and that for maximum infection. Infection did not occur until the plants were eight weeks old, after which the disease spread until the carrots matured. Initial penetration occurred by hyphal tips forcing their way between the cells of the periderm. Both intercellular and intracellular hyphae were formed abundantly but they did not become established beyond the cambium. Infection bodies began in cells of the periderm where intracellular hyphae accumulated in masses prior to breaking through the outer layer of periderm cells. Two types of histological response to infection were observed: In one a cork layer, formed beneath the infection bodies, resulted in the development of shallow lesions, whereas in the other the infected tissues were broken down and deep lesions were formed in the carrot.
STUDIES OF NEMATODES IN RELATION TO BROWN ROOT ROT OF TOBACCO IN ONTARIO
Authors: Mountain W. B.
Published: August 2008

The root-lesion nematode, Pratylenchus spp. is proved to be the primary causal agent of the brown root rot disease of tobacco in Ontario. The root lesions resulting from nematode attack are undoubtedly further broken down by the activity of other soil organisms. At least two species of Pratylenchus are involved, differing significantly in pathogenicity and morphology. Nine other parasitic and potentially dangerous nematode genera also were found associated with tobacco roots in Ontario, but they occurred in very low numbers. The effect of the preceding crop upon brown root rot of tobacco was found to be related to nematode populations; and for eight preceding crops, significant effects upon the growth of tobacco occurred only in the presence of high populations of parasitic nematodes. Since Pratylenchus minyus Sher and Allen, 1953, is the more pathogenic species, the relation between this nematode and the tobacco host was studied in some detail. The optimum soil temperature for this nematode is at least 100° F. and it causes little stunting of tobacco below a soil temperature of 70° F. In a resistant variety of tobacco studied, an unusual mechanism of resistance upholds a host–parasite equilibrium wherein, despite high populations of parasitic nematodes within the roots, normal plant growth is maintained.
TRANSLOCATION PATH AND PLACE OF ACTION OF 3-(4-CHLOROPHENYL)-1:1-DIMETHYLUREA IN BEAN AND TOMATO
Authors: Minshall Wm Harold
Published: August 2008

Except for a short time lag in the appearance of symptoms, a graded concentration series of CMU in water produced similar effects on intact plants and on excised tops of tomato and kidney-bean. When applied to roots, CMU had ready access to the vascular system and was quickly carried in the xylem to the tops. Wherever a lethal concentration was reached, the CMU killed the tissues of the leaves. As roots of treated plants lived for some days after the leaves were killed, the foremost toxic action of CMU must have taken place in the leaves.
DECAY IN POPLAR PULPWOOD IN STORAGE
Authors: Fritz Clara W.
Published: August 2008

Deterioration of poplar pulpwood (a mixture of Populus tremuloides Michx. and P. balsamifera L.) on Manitoulin Island, Ontario, was studied in field, pit, and block pile storage with reference to the reaction of the rot fungi present in the living tree to storage conditions, and the penetration of fungi which attack wood subsequent to felling. The rots found most prevalent in the living trees, and the most important from the standpoint of volume of wood affected, were the white trunk rots caused by Fomes igniarius var. populinus (Neu.) Campb., Radulum casearium (Morgan) Lloyd, Polyporus dryophilus var. vulpinus (Fr.) Overh., a rot associated with a non-Basidiomycete designated in this paper as Fungus X, and the brown rot produced by Poria cocos (Schw.) Wolf. The first four rots may survive in storage, but are not appreciably active. Butt rots caused by Armillaria mellea (Vahl.) Quél., Pholiota spectabilis (Fr.) Quél., and a gray–brown butt rot were not uncommon, but of limited importance both on account of the amount of wood attacked and the practical inactivity of the causal agents in storage. The only tree-rot fungus found likely to cause damage in storage was P. cocos; it produces brown rot and is capable of spreading vigorously in stored wood. Other tree rots occurred, but were of minor importance. Stereum purpureum Pers. was the first fungus to infect the wood after the trees were felled; it spread rapidly and fruited during the first summer. It was followed by three species of Polyporus, P. adustus (Willd) Fr., P. hirsutus (Wulf.) Fr., and P. versicolor (L.) Fr. These became established in the wood during the first summer; they fruited on field and pit logs during the second season, and were fruiting luxuriantly on block pile logs which had been stored three years. They produce white rots and in some logs caused advanced decay in two years' storage. Other storage rot and staining fungi were isolated from the bolts under study, but during the period of observation did not effect wide spread penetration. The same pattern of decay and succession of fungi were found in all types of storage investigated.
INVESTIGATIONS ON THE GENERA BEAUVERIA VUILL, AND TRITIRACHIUM LIMBER
Authors: MacLeod D. M.
Published: August 2008

A thorough review of the literature shows that 32 alleged species have been involved in the genera Beauveria and Tritirachium. Fourteen of these are reduced to synonymy with B. bassiana and B. tenella; ten belong to the form genus Tritirachium; one, "Tritirachium epigaeum", is regarded as uncertain as to genus; and seven are excluded from both. Beauveria stephanoderis, B. laxa, B. globulifera, B. effusa, B. vexans, B. doryphorae, B. delacroixii, and B. acridiorum are strains of B. bassiana; while B. densa, B. melolonthae, B. brongniartii, and B. shiotae are strains of B. tenella. The species T. dependens, T. album, T. spicatum, T. oryzae, T. heimii, T. brumpti, T. musae, T. purpureum, T. cinnamomeum, and T. roseum are characteristic of the form genus Tritirachium. Beauveria peteloti, B. rileyi, B. paranense, B. coccorum, B. coccospora, T. rubrum, and T. viannai are characteristic of neither genus. The above conclusions are based on a study of the cultural and morphological characteristics of numerous Beauveria isolates from 70 insect and four rodent species. Most characteristics adopted by earlier investigators to differentiate between Beauveria species are not valid as criteria upon which to establish species. Moreover, these characteristics are unstable and can be changed simply through monospore culturing or by transferring cultures from one type of medium to another. From a review of the literature, it is evident that: members of the genus Beauveria are primarily parasitic on insects, whereas members of the genus Tritirachium are primarily saprophytes.
STUDIES ON HEARTWOOD FORMATION AND STAINING IN SUGAR MAPLE, ACER SACCHARUM MARSH.
Authors: Good H. M. , Murray P. M. , Dale H. M.
Published: August 2008

Parenchyma cells of maple wood may live for more than a century though a considerable proportion die earlier. A few cells succumb each year making "heartwood" formation gradual. Post mortem deposits, primarily in the parenchyma cells, account for the deepened color of older maple wood. The pH, water content, and mineral content of the wood do not change appreciably with aging. Maple wood often becomes deeply stained. The stain is due to deposits in the parenchyma cells which, if killed before senescence sets in, produce a post mortem deposit which is darker and larger than that produced by cells dying of old age. Stained wood is distinctly alkaline and contains substantial amounts of minerals which accumulate in the stained region. These regions also have a higher moisture content than normal wood. The consistency with which stain is produced in advance of spreading decay fungi suggests that staining and the related chemical changes exert a considerable influence on decay in sugar maple.
STUDIES IN WOOD-INHABITING HYMENOMYCETES: II. CORTIC1UM VELLEREUM ELLIS AND CRAGIN
Authors: Nobles Mildred K. , Nordin Vidar J.
Published: August 2008

Corticium vellereum Ellis and Cragin was isolated frequently from rots of various types in living trees of Acer saccharum Marsh., which indicates that it invades wood already attacked by other fungi. A description of the characters by which cultures of C. vellereum may be identified is presented. The fungus is heterothallic and of the tetrapolar type of interfertility.
STUDIES OF WESTERN TREE RUSTS: II. MELAMPSORA OCCIDENTALIS AND M. ALBERTENSIS, TWO NEEDLE RUSTS OF DOUGLAS FIR
Authors: Ziller W. G.
Published: August 2008

Observations at selected field locations and results of repeated inoculations have shown that Douglas fir is an aecial host of Melampsora occidentalis Jacks. A brief account of the rust's life history is given and the aecial state is described from a specimen obtained by inoculation. Arthur's diagnosis of the aeciai state of M. albertensis Arth. is replaced by a new description based on a specimen obtained by inoculation. Caeoma occidentale Arth. is shown to represent the pycnial and aecial states of Melampsora occidentalis, not M. albertensis. The aecial states of M. albertensis and M. occidentalis, both occurring on Douglas fir needles, are identical in gross morphology and time of appearance in nature, but can easily be distinguished from each other by spore size.
THE INFLUENCE OF LIGHT AND DARKNESS ON THE METABOLISM OF RADIOACTIVE GLUCOSE AND GLUTAMINE IN WHEAT LEAVES
Authors: Bidwell R. G. S. , Krotkov G. , Reed G. B.
Published: August 2008

C14-Labelled glucose or glutamine was fed to wheat leaves in light or darkness, and several hours later the distribution of activity among the various plant constituents was determined following their separation by paper chromatography. From these data it was concluded that complete oxidation of glutamine to carbon dioxide proceeded at a greater rate in light than in darkness. In light glucose carbon was prevented from reaching pyruvic acid and the Krebs cycle to any great extent, but this block could be reversed by the application of ammonium nitrate to the leaves. Light or darkness had no effect on the respiration of glucose by Staphylococcus aureus.
MICROFUNGI: I. CORDANA, BRACHYSPORIUM, PHRAGMOCEPHALA
Authors: Hughes S. J.
Published: August 2008

Cordana pauciseptata is illustrated and redescribed from North American collections on wood and bark and from isolations from wood. The history of the genus is reviewed. Brachysporium apicole (syn. Monotospora triseptata, syn. Acrothecium anixiae) and Brachysporium obovatum are discussed, and North American collections as represented in Herb. DAOM are listed. Brachysporium polyseptatum (syn. B. bloxami) is illustrated and B. pendulisporum is described as new. Phragmocephala cookei and P. glandulaeformis (syn. P. minima) are recorded for North America.
THE APPLICATION OF A NUTRITIONAL GROUPING METHOD TO SOIL FUNGI
Authors: Atkinson R. G. , Robinson J. B.
Published: August 2008

In tests with seven different liquid media in which the common nitrogen source was potassium nitrate and the carbohydrate substrate was glucose, at a concentration of only 0.1%, most of the 1914 soil fungi isolated fell into one of three nutritional groups requiring, respectively, for maximum growth amino acids, amino acids plus growth factors, or yeast extract. Relatively few isolates required growth factors alone or a combination of yeast and soil extracts. Most of the isolates grew poorly in the basal medium containing only mineral salts, and glucose, with or without soil extract. Although fungi requiring yeast extract were much less frequently isolated from soil on, rather than remote from, tubers grown in a soybean green-manured plot, isolates requiring amino acids, or yeast plus soil extracts, were correspondingly increased on immature and mature tubers, respectively. In a second plot, however, not specially treated, no differences were observed in the nutritional spectra of fungi isolated from the two kinds of soil environment.
AN APPARATUS FOR DETERMINING THE EFFECTS OF TEMPERATURE AND HUMIDITY ON GERMINATION OF FUNGOUS SPORES
Authors: Hart Mary P. , MacLeod Donald M.
Published: August 2008

An apparatus is described by which fungous spores can be uniformly distributed on microscope slides. A procedure is outlined whereby Petri dishes can be converted into airtight humidity chambers, the humidity of which can be readily checked. It was found that above 94% relative humidity maximum germination among Beauveria bassiana spores occurs at 28 °C.
SEDIMENTARY CHLOROPHYLL DETERMINATION AS A PALEOBOTANICAL METHOD
Authors: Vallentyne J. R.
Published: August 2008

Chlorophyll degradation products which can be extracted from sediments with 90% acetone and which show maximal light absorption in the red end of the spectrum at a wave length of 667 mμ (90% acetone as the solvent) are here collectively defined as sedimentary chlorophyll. A quantitative method is described for the determination of sedimentary chlorophyll. Results from six different sediment profiles are presented. The nature of sedimentary chlorophyll is unknown, except that it consists of at least three chlorophyll degradation products. Sedimentary chlorophyll has been found in samples aged up to 11,000 years. In any one profile the fluctuations in sedimentary chlorophyll content may be used to infer changes in the abundance of chlorophyll-bearing plant tissues, but only with the greatest caution.
THE SEASONAL VARIATION IN CHEMICAL COMPOSITION OF MACROCYSTIS INTEGRIFOLIA AND NEREOCYSTIS LUETKEANA IN BRITISH COLUMBIA COASTAL WATERS
Authors: Wort D. J.
Published: August 2008

Macrocystis integrifolia and Nereocystis luetkeana were collected at Port Hardy and Vancouver, B.C., respectively, at monthly intervals October 1949 through September 1951. Analyses of fronds and of stipes were made for dry weight, ash, total nitrogen, total phosphorus, sulphur, copper, zinc, iron, ether-solubles, algin, mannitol, fucoidin, and laminarin. Generally speaking the fronds had a higher content of all substances measured than did the stipes, and the content of the two species of algae showed parallel variation but differed in values. Dry weight and ash were at maxima in late fall and winter and at minima in April and May. During March total nitrogen, ether-solubles, mannitol, fucoidin, and laminarin were at their highest concentration. The plants in July contained the minima of total nitrogen, phosphorus, and ether-solubles. The maximum for phosphorus occurred in December and during this same month fucoidin was at minimum. The variation of sulphur, copper, zinc, iron, and algin was such that well marked minima and maxima were not evident.
THE NATURE OF THE INHIBITING SUBSTANCE EMITTED BY GERMINATING UREDIOSPORES OF PUCCINIA GRAMINIS VAR. TRITICI
Authors: Forsyth F. R.
Published: August 2008

The self inhibition of germination of urediospores of Puccinia graminis Pers. var. tritici Erikss. & Henn. has been consistently demonstrated in Warburg flasks. Four ways of overcoming the effect of the inhibitory substance have been discovered: use of a sufficiently large volume of water in relation to weight of spores; the placing of a silver nitrate solution in the center well; and the introduction of acetone or ammonia vapor into the flask atmosphere. The vapor of trimethylethylene inhibits germination of the urediospores in the same way that the natural inhibitor does, and the same means can be used to counteract its effects. The similarity of the absorption spectra of the inhibitor and of trimethylethylene in acetone solutions indicates that trimethylethylene is the natural inhibitor. Cyclohexene has formative and inhibitory effects on the germ tubes and these effects can be overcome by vapor of acetone.
SEEDLING BLIGHT, A FUSARIAL DISEASE OF ASPARAGUS
Authors: Graham K. M.
Published: August 2008

Incidence of seedling blight in Ontario can be correlated with proximity of mature plantations or with the presence of debris from a previous asparagus crop. As the disease was detected on seedlings grown in soil from "volunteer" plants growing in isolated habitats, the pathogen is considered to be indigenous. The pathogen penetrates directly into the embryonic region of the root tip, or through stomata on the hypocotyl, and colonizes the host both intercellularly and intracellularly. Its limitation to the cortex is regarded as unusual among the parasitic fusaria, which are mainly vascular. The fungus was identified as Fusarium oxysporum sensu Snyder & Hansen var. redolens (Wr.) Gordon. In comparison with F. moniliforme Sheldon, found to cause a root tip necrosis of asparagus seedlings, the cortical Fusarium produced less growth on basal medium plus cellulose but more growth on sucrose, and showed a greater ability to hydrolyze starch. Differing nutrient preferences are suggested as one explanation for the localized types of colonization exhibited by these two fusaria. The optimum soil temperature for disease incidence was established at 25°-30 °C. The effect of temperatures above 30 °C. is considered to be twofold: (1) inhibiting growth of the pathogen and (2) permitting the host to escape by inducing its more rapid emergence. Below 20 °C, the pre-emergence phase of the disease is favored by a retardation of the rate of emergence. Both low and high levels of soil moisture retard emergence and favor pre-emergence blight. Under greenhouse conditions, incidence of the disease usually increased more rapidly when leguminous rather than nonleguminous residues were present in the soil and there was some evidence that the saprophytic growth of the pathogen was more profuse on certain nonliving substrates.
POLLEN PROFILES FROM THE QUEEN CHARLOTTE ISLANDS, BRITISH COLUMBIA
Authors: Heusser Calvin J.
Published: August 2008

Five peat sections were excavated from muskegs on Langara, Graham, and Moresby Islands of the Queen Charlottes with the primary purpose of reconstructing the postglacial plant succession and associated climatic and physiographic alterations. A secondary purpose was to support or disprove the geological and zoological data favoring the existence of refugia in which biota survived from preglacial or interglacial time. The oldest pollen record tends to support this contention. The record is older than any derived from sections heretofore studied on the northwest coast. Twenty-three plant entities are represented in the bottom sediments below the lodgepole pine maximum which in these other sections marks the oldest peat. In addition, 27% of the coniferous pollen at the base of the section is constituted of climax forest trees, thus implying the presence of long-established forest when pollen sedimentation began. The number and kinds of pollen in the basal peat favor the interpretation that vegetation persisted in refugia through at least the last glaciation. The pollen profiles further corroborate earlier findings for changes in land–sea level relations and for the following postglacial climatic sequence: early cool-moist, warmer and drier (thermal maximum), and late cooler and wetter.
THE PEACH REPLANT PROBLEM IN ONTARIO: I. SYMPTOMATOLOGY AND DISTRIBUTION
Authors: Koch L. W.
Published: August 2008

In Ontario, serious difficulties are frequently encountered in the establishment of young peach trees as replacements in old orchard sites. Symptoms vary from slight stunting to complete absence of growth. Causal factors described in conflicting reports in literature on the subject and information gained from examination of affected trees attest to the complexity of the problem. The failure of the replanted trees has been ascribed to the activity of insects and nematodes as well as to the effect of nutritional disturbances, toxic agents, and spray residues. The problem is being studied as a co-ordinated investigation by plant pathologists, entomologists, microbiologists, horticulturists, nematologists, and chemists. The account given here is introductory to a series of papers dealing with the various phases of the investigation and includes mainly a review of the literature and a description of the symptoms and effects of the disorder.
THE PEACH REPLANT PROBLEM IN ONTARIO: II TOXIC SUBSTANCES FROM MICROBIAL DECOMPOSITION PRODUCTS OF PEACH ROOT RESIDUES
Authors: Patrick Z. A.
Published: August 2008

Experiments were carried out to evaluate the importance of soil toxins in the peach replant problem and to determine whether the substances produced by the interaction of microorganisms occurring in old peach orchard soils and peach root residues were toxic to living peach roots. A rapid and accurate indication as to whether or not these substances were toxic was obtained by determining their effect on the respiration of excised peach root tips. It was demonstrated that substances which inhibit the respiration of excised peach root tips are produced when peach root residues, and also, chemically pure amygdalin, are acted on by certain microorganisms occurring in old peach orchard soils. Such substances were not produced when the soils were autoclaved before amygdalin was added or when other soils were used in which no breakdown of amygdalin had occurred. Again no such inhibiting substances were produced when other root residues, such as sour cherry, tobacco, or pepper roots, were added to these soils in place of peach root residues or amygdalin. The inhibiting substances were readily obtained by extraction with water and they proved to be highly active physiologic agents; the inhibiting effect on the respiration of peach root tips, which ranged from 40 to 90%, could be detected after tips had been less than half an hour in the toxic leachates. In addition to inhibiting respiration these substances also induced darkening and finally the necrosis of meristematic cells. All of these effects proved to be irreversible after tips had been five hours in the toxic leachates. The root tips were apparently killed after this time. Parallel experiments were carried out also with pure amygdalin, and similar inhibition of respiration and injurious effects on meristematic cells were obtained with microbial degradation products of either amygdalin or peach root residues. Water solutions of amygdalin, emulsin, amygdalin and emulsin combined, and various benzaldehyde dilutions were also tested. Inhibition of respiration and darkening of apical meristems were only obtained, however, in solutions where amygdalin was hydrolyzed by emulsin and in the various concentrations of benzaldehyde in water. They were not obtained in the separate solutions of either the glycoside or the enzyme. It was concluded, therefore, that microbial action on the amygdalin fraction of peach roots is mainly responsible for the toxic factor frequently encountered in old peach orchard soils.
CHRYSOMYXA IN NORTH AMERICA—ADDITIONS AND CORRECTIONS
Authors: Savile D. B. O.
Published: August 2008

Chrysomyxa ledi var. glandulosi Savile on Ledum glandulosum, C. ledi var. groenlandici Savile on L. groenlandicum, and C. ledi var. vaccinii Ziller on Vaccinium parvifolium are recognized as new varieties distinct from C. ledi var. ledi on L. palustre. Host and range extensions are given for several taxa, notably C. ledi var. rhododendri and C. woronini. The biology of the latter species is discussed.
THE PRODUCTION OF MUTATIONS BY THE IRRADIATION OF MONTCALM BARLEY
Authors: Lawrence Thomas
Published: August 2008

Five radiation sources were used to induce mutations in barley. All treatments were given at a dosage of 10,000 r. equivalent. The radiation sources with their respective dose-rates in the region of the irradiated seeds were: a betatron (181.8 r./min.), an X-ray machine (201 r./min.), radium-beryllium (5.3 r./min.), and two Co60 sources (4.5 r./min. and 75.75 r./min.). None of the radiation sources used was more effective than the X-ray treatment in producing mutations. The betatron and the high dose-rate treatments from Co60 appear to be somewhat less effective than X-rays. Over 30 different mutant types were produced, including a number of vital mutants, such as stiff-strawed and early-maturing types. These appear promising as new varieties, but require further agronomic evaluation. It is concluded that mutation induction will become a useful new approach for plant breeders.
THE SEED PRODUCTION CAPACITY AND EFFICIENCY OF RED PINE CONES (PINUS RESINOSA AIT.)
Authors: Lyons L. A.
Published: August 2008

The seed capacity of red pine cones varies from about 30 to over 110, depending on the size of the cone and its position in the tree crown, and is determined by the number of ovules that are structurally complete at the time of pollination. These ovules occur in a central "productive" region and constitute less than one-half of the total. The remaining ovules, most: of which are in the proximal part of the cone, never become structurally perfect, and do not contribute to seed production. Abortion of ovules in the productive region usually reduces seed production efficiency to 50–60%, and is accompanied mainly by withering of the nucellus in the first year and failure to produce archegonia early in the second year. The extent of ovule abortion during the first year varies indirectly with cone size, seed capacity, and height in tree.
LABORATORY DETECTION OF CORYNEBACTERIUM SEPEDONICUM, CAUSAL AGENT OF BACTERIAL RING ROT OF POTATOES
Authors: Katznelson H. , Sutton M. D.
Published: August 2008

Studies are described on the laboratory detection of bacterial ring rot of potatoes caused by Corynebacterium sepedonicum (Spieckermann and Kotthoff) Skaptason and Burkholder. A cultural–microscopic procedure, involving the preincubation of aseptically removed infected material on a suitable medium, was found in general to be more reliable than direct examination of Gram-stained smears from diseased material. This was especially noticeable with lightly infected potatoes. The use of both methods would likely decrease the possibility of incorrect diagnosis. A serological method also was found to be of value in detecting ring rot in tubers and in plant extracts. Antiserum for one typical strain of C. sepedonicum (CS850) agglutinated all strains tested, and also reacted with all infected samples examined but not with uninfected material. This organism might be used to prepare bulk antiserum for distribution to various laboratories engaged in the diagnosis of bacterial ring rot. Attempts to isolate a phage for C. sepedonicum were unsuccessful.
ON THE MECHANISM OF INDOLEACETIC ACID OXIDATION BY WHEAT LEAF ENZYMES
Authors: Waygood E. R. , Oaks Ann , Maclachlan G. A.
Published: August 2008

Partially purified enzyme preparations of wheat leaves oxidize indoleacetic acid completely in the presence of manganese and a monohydroxyphenol or resorcinol. A characteristic feature of the oxygen uptake is an induction period followed by a rapid oxygen uptake which ceases when 1 mole of oxygen is consumed per mole indoleacetic acid added. One mole of carbon dioxide is evolved per mole indoleacetic acid. There is no lag in carbon dioxide evolution, but it is not given off anaerobically. Oxygen, blue light, and acetaldehyde overcome the induction period. Hydrogen peroxide formed in a final aerobic dehydrogenase step is utilized to provide a source of manganic ions which act as an electron acceptor in an initial oxidative step.
NATURAL HYBRIDIZATION BETWEEN CARDUUS ACANTHOIDES AND CARDUUS NUTANS IN ONTARIO
Authors: Moore R. J. , Mulligan G. A.
Published: August 2008

A survey was made of the occurrence of natural hybrids between two species of introduced thistles, Carduus acanthoides L. var. acanthoides and C. nutans L. var. nutans, in Grey County, Ontario. The population of one field was studied in detail. Specimens were taken and their morphological variation was evaluated by means of a hybrid index. These species have different chromosome numbers: C. acanthoidcs L., 2n = 22; C. nutans L., 2n = 16. All the intervening numbers were found in the hybrids. There is a clear correlation between chromosome number and hybrid index: plants with the chromosome number of a first generation hybrid have an index intermediate between those of the parental species. The chromosome numbers of seedlings raised from seed collected from hybrid plants were determined. It was found that seedlings with the number 2n = 22 were much more frequent than those with other numbers. It is suggested that both ecological and gametic selection are acting in this area to favor production and survival of plants with the chromosome number and morphology of C. acanthoides.
PURIFICATION AND ELECTRON MICROSCOPY OF VIRUSES CAUSING CHERRY YELLOWS AND RELATED DISEASES
Authors: Willison R. S. , Weintraub M. , Ferguson J. D.
Published: August 2008

Virus entities associated with necrotic ring spot, yellows, and green ring mottle of sour cherry, tatter leaf of sweet cherry, prune dwarf, and two viroses of rose have been purified and concentrated from cucumber leaves and/or peach and cherry petals and peach leaves by differential centrifugation. To prevent inactivation of the virus, the Prunus tissues were homogenized with 0.1% potassium cyanide in 2.5% sodium bisulphite. Infective extracts of some of the entities were also prepared by ammonium sulphate precipitation and from aqueous chloroform–amyl-alcohol emulsion. Particles ranging from less than 10 to more than 100 mμ in diameter were observed with the electron microscope in extracts from both healthy and virus-infected sources. In the former, prepared by differential centrifugation, particles were distributed about a series of peaks at 10 mμ intervals and, in the latter, about a single mode characteristic of the entity under examination. Particles associated with different entities ranged from 28 mμ diameter for rose mosaic to 50 mμ for some tatter leaf and green ring mottle isolates. In extracts known to contain two viruses, characteristic distributions of each component of the mixture could be determined if the mean particle diameter of one virus was known and differed from that of the other entity by 5 mμ or more. Evidence based on particle characteristics, supplemented by cross protections and comparative symptomatology suggests that the necrotic ring spot virus is not necessarily involved in the etiology of cherry yellows, prune dwarf, tatter leaf, or green ring mottle.
STUDIES IN WOOD-INHABITING HYMENOMYCETES: III.STEREUM PINI AND SPECIES OF PENIOPHORA SECT. COLORATAE ON CONIFERS IN CANADA
Authors: Nobles Mildred K.
Published: August 2008

The Section Coloratae of the genus Peniophora is represented in Canada by Peniophora septentrionalis Laurila, frequently associated with a red stain and white rot in Picea spp., P. pithya (Pers.) J. Eriksson, not previously recorded from North America, and P. separans Burt, of which only two collections, made in 1921, were known. Descriptions of sporophores and cultures, with results of interfertility tests and records of hosts and geographical distribution, are presented for these species, for Stereum pini (Schleich. ex Fr.) Fr., associated with a red stain and white rot in Pinus spp., and for an undetermined species isolated from saprot in Pinus banksiana.
A VIRUS LATENT IN TURNIPS
Authors: MacKinnon J. P.
Published: August 2008

Green peach aphids reared on turnip stecklings acquired a virus that was transmitted to plants of Physalis floridana Rydb. and P. pubescens L., hosts used in potato leaf roll studies. Symptoms on these hosts consisted of a yellowing of the veins of the leaves. Nicandra physalodes L., when infected, showed severe stunting and chlorosis. The virus was carried without symptoms on turnips and showed only slight stunting on several species of Brassica. It was not transmitted by mechanical inoculation and it does not appear to be similar to any of the viruses previously reported in turnips. The aphid Myzus persicae (Sulzer) acquired the virus during a seven-hour feeding period, and after a latent period of approximately 23 hr., transmitted the virus during a one-hour test-feeding period. Once infective, aphids remained so for several days.
PHOTOSYNTHETIC INDUCTION IN MARINE ALGAE
Authors: Clendenning K. A. , Haxo F. T.
Published: August 2008

Effects of dark time and of oxygen supply upon photosynthetic induction in Ulva were investigated polarographically and manometrically. Under continuously aerobic conditions, the induction period was of about two minutes' duration following one day in darkness in flowing sea water; beyond 10 min., length of the aerobic dark period had little effect. The induction period was lengthened by dark anaerobiosis, but was not eliminated entirely by dark aeration or oxygenation treatments. Aerobic induction periods of similarly brief duration were observed in Ulva, Gigartina, and Gelidium fronds which corresponded with those established previously for leaves and unicellular algae. Aerobic induction is attributed to an initial lack of "CO2-acceptor" which is regenerated photosynthetically. Interpretations are provided for the widely different induction periods and saturating carbon dioxide concentrations which had been observed in earlier studies of photosynthesis in attached marine algae.
STUDIES IN AMERICAN ORCHIDS. I
Authors: Garay Leslie A.
Published: August 2008

Sixteen species of tropical American orchids are described as new, and nine new combinations of taxonomic importance are proposed. These are arranged in systematic order as follows: Xerorchis trichorhiza (Krzl.) comb. nov.; Sobralia kermesina sp. nov.; Cranichis Asplundii sp. nov.; Spiranthes decora sp. nov.; Spiranthes Wendlandiana (Krzl.) comb. nov.; Erythrodes Ortgiesii (Hort.) comb. nov.; Physosiphon Bangii (Schltr.) comb. nov.; Lepanthes hemirhoda sp. nov.; Lepanthes macrantha sp. nov.; Lepanthes palmaritoensis sp. nov.; Lepanthes pendens sp. nov.; Lepanthes Vareschii sp. nov.; Pleurothallis Killipi sp. nov.; Pleurothallis pachypus (Lehm. & Krzl.) comb. nov.; Pleurothallis Tunguraguae var. minor var. nov.; Epidendrum Cuatrecasasii sp. nov.; Scaphyglottis flaccida (Krzl.) comb. nov.; Orleanesia maculata sp. nov.; Polycycnis ornata sp. nov.; Maxillaria cuencana nom. nov.; Maxillaria pleuranthoides (Schltr.) comb. nov.; Rodriguesia Strobelii sp. nov.; Dipteranthus planifolius (Rchb.f.) comb. nov.; Telipogon ochraceus sp. nov.; Telipogon roseus sp. nov.
CYTOTAXONOMY AND SEX DETERMINATION OF RUMEX PAUCIFOLIUS
Authors: Löve Áskell , Sarkar Nina
Published: August 2008

The western North American dioecious species Rumex paucifolius is shown to be a tetraploid with 2n = 28 chromosomes. It is the third tetraploid known within the subgenus Acetosa, and the first polyploid dioecious taxon of that group, the others having either 2n = 14 ♂, 15 ♀ (R. Acetosa and relatives), or 2n = 8 ♂, 9 ♀ (R. hastatulus). The sex chromosomes of R. paucifolius are of the XX:XY type, the male sex being heterogametic. The X is a large chromosome, while the Y is the smallest chromosome of the complement. The mechanism of sex determination of R. paucifolius follows the Melandrium–Acetosella scheme with strongly epistatic male determinants in the Y–chromosome. Other dioecious Acetosae follow the Drosophila–Acetosa scheme of sex determination with a balance between the number of X and autosome complements, the Y being sexually inert. It is concluded from the observed cytogenetical and morphological differences that R. paucifolius should constitute a section of its own, Paucifoliae, which should be placed as far as possible from the section Acetosa, though within the same subgenus. The other American dioecious endemic, R. hastatulus, is placed in a subsection of the section Acetosa.
THE NATIVE PLANTS OF CHURCHILL, MANITOBA, CANADA
Authors: Ritchie J. C.
Published: August 2008

The object of the paper is to provide as complete an account as is possible of the native vascular plants of a circumscribed area near Churchill, Manitoba, on the west coast of Hudson Bay. Preceded by an account of earlier major collections and reports, brief surveys of the topographical, geological, and climatic features of the region are presented. Associated with the four main topographical types there are discrete groups of plant communities; they are described in general, qualitative terms. An annotated account of the 270 entities of native vascular plants found in the area is submitted, in which autecological notes and data of distribution are appended to the name of each species. There are seven additions to the known flora of Manitoba; one new variety is described. The geographical affinities of the flora are examined, in broad outline, and it is shown that the flora consists of 53% arctic and subarctic plants, 45.5% boreal and 1.5% cosmopolitan species. Six species have amphi-Atlantic areas, and nine belong to that group of plants which have their main areas in North America with outlying stations in Northwest Europe.
CYTOLOGICAL STUDIES OF HELMINTHOSPORIUM SATIVUM
Authors: Hrushovetz S. B.
Published: August 2008

Cytological studies of Helminthosporium sativum P.K. & B. showed that a mechanism exists for the perpetuation of heterokaryons. Septa are laid down in such a way that usually the hyphal tips and mycelial cells are initially multinucleate. Hyphal fusions occur in all parts of the colony and nuclei have been observed in the bridging hyphae. Two or more nuclei generally enter the young conidiophore and several nuclei invariably enter the young conidium before the latter is delimited from the conidiophore. The multicellular, multinucleate conidia exhibit polar or bipolar germination but only the nuclei in the terminal cells of the conidium enter the germ tubes; the remaining cells and their nuclei subsequently degenerate. Germination of complete conidiophores or portions of conidiophores was also observed.
CONTRIBUTION TOWARDS A MONOGRAPH OF THE GENUS STELIS SW.
Authors: Garay Leslie A.
Published: August 2008

The various categories within the genus Stelis are discussed. In Part I the history of the genus is given as well as an analysis of the Lindleyan classification which is shown to be artificial. A system of classification is proposed using what appears to be more constant and therefore more significant characteristics. In Part II new species are described and arranged according to the proposed system. These species are as follows: Stelis convallarioides sp. nov.; Stelis Jamesoni Lindl. var. parviflora, var. nov.; Stelis papillosa sp. nov.; Stelis cochlearis sp. nov.; Stelis navicularis sp. nov.; Stelis rhomboidea sp. nov.; Stelis sanguinea sp. nov.; Stelis genychila sp. nov.; Stelis tenuipetala sp. nov.; Stelis cryptochila sp. nov.; Stelis violascens sp. nov.; Stelis ecallosa sp. nov.
PHOTOPERIODIC RESPONSE IN GERMINATION OF SEED OF CERTAIN TREES
Authors: Vaartaja O.
Published: August 2008

Unstratified seeds of Betula pubescens Ehr. and B. verrucosa Ehr. exhibited low or no germination at temperatures from 10° to 20 °C. unless exposed to continuous illumination or illumination interrupted only by a short daily dark period. Germination was high even under a short primary light period if the long dark period was divided into two short ones by an additional daily light period. Besides these true photoperiodic responses, germination was slightly correlated to illumination intensity and to the amount of light. Germination was somewhat reduced when the illumination intensity was either decreased or increased from an optimum. At temperatures of 20° to 25 °C., germination was fair, even under a short daily light period. At still higher temperatures no light was needed for maximum or nearly maximum germination. Seeds of three other tree species also germinated better if exposed to long light periods, but the differences were small or not significant statistically. In most of the experiments the effect of temperature was separated from that of light by using running water as the germination medium. The antibiotic Rimocidin as well as various other chemicals and ultrasonic treatments failed to affect the germination of B. verrucosa.
STUDIES ON RUBUS VIRUS DISEASES IN BRITISH COLUMBIA: III. SEPARATION OF COMPONENTS OF RASPBERRY MOSAIC
Authors: Stace-Smith Richard
Published: August 2008

It has been shown that the mosaic disease of red raspberry is the result of multiple infection by two separate viruses. Since these viruses, tubus yellow-net and black raspberry necrosis, have a common, vector, the aphid Amphorophora rubi Kalt., and are both nonpersistent, they are usually transmitted together and the complex nature of the mosaic disease can best be demonstrated by synthesis.