Hypoxylon Mammatum Research Articles

Germination of ascospores of Hypoxylon mammatum in living aspen

Ascospores of Hypoxylon mammatum germinated in the sapwood of naturally occurring trembling aspen. Observed germination never exceeded 7%. There appeared to be no clear relationships between percentage germination and the age of the wound, location in the sapwood, age of the tree, or weather conditions during the incubation period.

Isolation of Hypoxylon mammatum from aspen stem sections

Hypoxylon mammatum developed in noninoculated aspen stem sections which had the top ends dipped in paraffin and were then placed in moist sand, at 24C and 90% humidity for 3 months. The development of the fungus in the stem sections might have been due to the presence of ascospores or mycelium on or in the outer tissues of the stems.

Alteration of Sugar Translocation in Aspen by Hypoxylon mammatum

Alteration of Sugar Translocation in Aspen by Hypoxylon mammatum

Benzoic and salicylic acids isolated from a glycoside of aspen bark and their effect on Hypoxylon pruinatum

Benzoic and salicylic acids, isolated from an unknown glycoside of aspen bark, were identified as the main fungistatic factors of this compound against Hypoxylon pruinatum (Klotzsche) Cke. The identity of the carboxylic acids was established by thin-layer chromatography and ultraviolet and infrared spectrophotometry.On a malt agar medium, benzoic acid inhibited the growth of the fungus at 1 × 10−3 M, whereas salicylic acid at the same concentration stimulated growth. Complete inhibition of growth of the fungus was obtained with benzoic acid at a concentration of 4 × 10−3 M and with salicylic acid at 5 × 10−3 M. Total inhibition was also obtained when both benzoic and salicylic acids, each at a concentration of 2 × 10−3 M, were simultaneously present in the malt agar medium.On a synthetic medium, benzoic acid and glucose, each at a concentration of 1 × 10−3 M, inhibited the growth of the fungus. At this concentration salicylic acid had no effect.When ammonium nitrate was replaced simultaneously by asparagine, alanine, and glutamine, benzoic acid at 2 × 10−3 M, and glucose at 3 × 10−3 M promoted the growth of the fungus. The same growth was also obtained when benzoic acid at 1 × 10−3 M and glucose at 1 × 10−3 M were both added to the medium.

Factors affecting canker development on Populus tremuloides artificially inoculated with Hypoxylon pruinatum

A technique was devised for obtaining extensive canker development on wounded greenhouse-grown aspens (Populus tremuloides Mich.) inoculated with mycelium of Hypoxylon pruinatum (Klot.) Cke. Cankers developed rapidly only on water-stressed plants, and under such conditions often averaged 75 mm in length within 10 days. Alcohol treatment of stems before inoculation did not affect the course of canker development. Cankers developed most rapidly on plants watered every third or every fifth day, and developed least in plants watered daily. Stem wounds exposing the wood were essential for canker development. Wounds required an 8-day period before inoculation to heal sufficiently to inhibit canker development. Wound sites midway on the stem were most susceptible to canker development, while sites near the growing point were the least susceptible. Time for symptom appearance was prolonged in inoculated plants of larger diameters.

Pathogenicity and taxonomy of Hypoxylon mammatum

Typical cankers with stromata were produced when aspen were inoculated with isolates of Hypoxylon mammatum (H. pruinatum) from aspen, but isolates from alder and willow were incapable of producing typical cankers on aspen. Isolates from willow produced cankers initially, but these were eventually callused over. Isolates from alder and aspen were not able to incite cankers on alder. Dimensions of the perithecia and ascospores of the fungus on aspen are not sufficiently different from those on birch, willow, and alder to justify maintaining H. pruinatum as a species separate from H. mammatum.

Decarboxylation of Benzoic Acid by Hypoxylon pruinatum

Decarboxylation of Benzoic Acid by Hypoxylon pruinatum

NOTES ON HYLPOXYLON CANKER OF ASPEN IN ALBERTA

The rate of canker growth, caused by HYPOXYLON PRUINATUM (Klotzsch) Cke. (H. MAMMATUM (Wahl.) Miller) and the intensification of the disease were investigated on trembling aspen, POPULUS TREMULOIDES Michx. in Elk Island National Park, Alberta. In 1963, 45.1 per cent of the trees on a 1/3-acre plot were either killed or infected. This number increased to 49.0 per cent during the following three years. All stem cankers were located below the 9 foot level and 75.0 per cent were facing north or northeast. The disease was not confined to a particular crown class. Infected, trees were killed in 4 to 8 years. Fifteen cankers were sectioned to study the nature of canker growth. The rate of girdling was not related to either the diameter or dominance of the tree. The cankers grew at a faster rate on dominant and co-dominant trees during the initial year of infection than on intermediate and overtopped trees. The disease did not cause increment loss during the infection period.

EJECTION AND DISSEMINATION OF ASCOSPORES OF HYPOXYLON PRUINATUM

The duration of ejection of ascospores of Hypoxylon pruinatum was dependent on the moisture condition of perithecial stromata, which in turn was affected by relative humidity and air temperature. Times of peak spore collection were usually correlated with times of high relative humidity and low air temperature, but when stromata were kept moist, peak spore collections occurred on a 12-h cycle regardless of relative humidity and air temperature, presumably because of overcrowding of perithecia with spores. Felling aspen bearing Hypoxylon cankers did not significantly reduce the numbers of spores liberated from these cankers until after 23 months. Eradicating cankers from an isolated aspen stand over a several year period did not reduce the number of new infections in that stand because cankers overlooked in the surveys continued to liberate spores, and probably because spores were brought in by wind from outside the stand. The pattern of ascospore movement in a deciduous forest was traced from a known source and the significance of this movement in relation to long distance dissemination is discussed.

FACTORS AFFECTING THE GERMINATION OF SPORES OF HYPOXYLON PRUINATUM

The optimum temperature for germination of ascospores of Hypoxylon pruinatum was 32 °C. and for conidia was 25 °C. Ascospores germinated best at pH 6.1. Both conidia and ascospore germination was inhibited on both unwounded and freshly wounded aspen bark. Inhibition was greatest on freshly wounded bark. Ascospore germination was 1.9% after 96 h on 2% malt agar containing 660 p.p.m. pyrocatechol, while complete inhibition occurred at 330 p.p.m. of the chemical in distilled water. Experiments suggest that the 48-h delay in spore germination was not due to the direct action of contaminating microorganisms.

INHIBITION OF HYPOXYLON PRUINATUM (KLOTZSCHE) CKE. BY ASPEN BARK MEAL AND THE NATURE OF ACTIVE EXTRACTIVES

The inhibitory power of poplar bark against the growth of Hypoxylon pruinatum (Klotzsche) Cke. was demonstrated on autoclaved bark meal agar. Activity varied with the species, time of cutting, and locality, but was highest in the bark of Populus tremuloides Michx. Maximum activity occurred in the roots and decreased towards the top of the tree. Neutral, basic, and acid fractions obtained from active ethyl acetate extracts of aspen bark showed seasonal quantitative variations which were characteristic for each fraction and for the part of the tree sampled. The acid fraction contained three active compounds: pyrocatechol, an undetermined phenol, and a glycoside (R). The neutral fraction contained an active glycoside (W). Glycoside (R) was mainly concentrated in the lower stem and glycoside (W) in the upper stem. The concentration of the two glycosides in the bark varied with locality. The influences of pH, temperature, and different chemicals on the fungistatic action of pyrocatechol were investigated to elucidate their rôle in disease resistance. In wilting tests, poplar leaves showed a light necrosis at 1320 p.p.m. of pyrocatechol, whereas 165 p.p.m. were lethal to tomato plants.

Microorganisms Associated with Hypoxylon Pruinatum

Microorganisms Associated with Hypoxylon Pruinatum

Microorganisms Associated with Hypoxylon pruinatum

Microorganisms Associated with Hypoxylon pruinatum

SOME INOCULUM FACTORS IN PATHOGENICITY STUDIES OF HYPOXYLON PRUINATUM (KLOTZSCHE) CKE. ON POPULUS TREMULOIDES MICHX.

Inoculum type was an important factor in pathogenicity studies of Hypoxylon pruinatum (Klotzsche) Cke. on Populus tremuloides Michx. The percentages of infection from bark meal and mycelial inocula were superior to that from agar plug inoculum, irrespective of whether the bark wounds were superficial or exposed the cambium and xylem. In experiments with mycelial inoculum it was demonstrated that autoclaved and living bark without inhibiting microorganisms were favorable to the growth of the pathogen. However, mycelial growth and infection were prevented when an abundance of bark saprophytes was applied to the host before inoculation. It appeared that the susceptibility or resistance of living bark to infection may have been more closely related to microbiological than chemical factors of the host tissues.

Further Effects of Bark Saprophytes on Hypoxylon Canker

Further Effects of Bark Saprophytes on Hypoxylon Canker

Pleospora Associated with Hypoxylon pruinatum

Pleospora Associated with Hypoxylon pruinatum

ACTI-DIONE AND NATURAL BARK EXTRACTS IN THE CONTROL OF HYPOXYLON CANKER OF POPLAR

Canker attack by Hypoxylon pruinatum (Klotzsch) Cke. did not occur when inoculations were made on dormant cuttings of Populus trichocarpa Torrey and Gray that had been dipped in a 1/10,000 aqueous solution of Acti-dione concentrate, and provided with a continuous water supply. However, the antibiotic was not successful in disease control when water was withheld temporarily from the dipped and inoculated cuttings. Canker spread was arrested when water was supplied to these partially dried cuttings, although it was evident that the antibiotic had caused injury to the developing shoots and roots. The results demonstrated that successful control by Acti-dione was dependent on the maintenance of normal water relations in the experimental trees.The Acti-dione tests are discussed in relation to the excellent control obtained in earlier experiments by the application of extracts of bark saprophytes to susceptible host material.

Inhibition of Hypoxylon pruinatum by pyrocatechol isolated from bark of aspen.

Pyrocatechol has been identified as one of two main substances isolated from bark of aspen (Populus tremuloides Michx.) which inhibited Hypoxylon pruinatum (Klot.) Cke. Total inhibition of this fungus was obtained at a dosage of 640 parts per million. Tests with bark extract from two localities showed that inhibition was maximal in samples obtained in the dormant season and from the base of the trees.

THE RELATION OF BARK MOISTURE TO THE DEVELOPMENT OF CANKER DISEASES CAUSED BY NATIVE, FACULTATIVE PARASITES: VII. SOME EFFECTS OF THE SAPROPHYTES ON THE BARK OF POPLAR AND WILLOW ON THE INCIDENCE OF HYPOXYLON CANKER

It has been shown that saprophytes were prevalent at the nodes, lenticels, and other irregularities on 1-, 2-, and 3-year-old bark of Populus trichocarpa Torrey and Gray and Salix sp. Antagonism tests demonstrated that the extracts of natural bark and two of the most common saprophytes inhibited the growth of Hypoxylon pruinatum (Klotzsch) Cke. However, the extracts of surface-sterilized bark were found to promote the cultural growth of the pathogen. No differences were observed in the behavior of the extracts obtained from dormant and actively growing bark tissues.The results of inoculation experiments demonstrated that Hypoxylon canker did not develop when the saprophytes were present on watered greenwood cuttings of black Cottonwood and willow. However, the saprophytes were not effective in preventing infection and canker growth on cuttings with below-normal levels in bark turgor. Surface-sterilized cuttings proved susceptible to the disease at all levels of bark turgor.Possible relationships between the temperature and moisture requirements of the pathogen and representative bark antagonists, and the epidemiology of canker diseases caused by facultative parasites, are discussed.