A SLIDE TECHNIQUE FOR THE STUDY OF FUNGI AND ACTINOMYCETES IN SOIL WITH SPECIAL REFERENCE TO HELMINTHOSPORIUM SATIVUM

1953 ◽  
Vol 31 (6) ◽  
pp. 718-724 ◽  
Author(s):  
S. H. F. Chinn
Keyword(s):  
Special Reference ◽  
Soybean Meal ◽  
Fusarium Culmorum ◽  
Natural Soil ◽  
Penicillium Notatum ◽  
Amended Soils ◽  
Helminthosporium Sativum ◽  
Stachybotrys Atra ◽  
Slide Technique ◽  
Germ Tubes

A slide technique suitable for studying the behavior of fungi and actinomycetes both qualitatively and quantitatively in soil is described. Besides Helminthosporium sativum, eight other fungi and one actinomycete were used to demonstrate the applicability of the method which was used for both natural and soybean meal amended soils. In the natural soil spores of Penicillium notatum, Stachybotrys atra, and the actinomycete only germinated. However, lysis or disintegration of the germ tubes of the two fungi was observed on the fourth day. Growth of the actinomycete was continuous to at least the seventh day. In the amended soil only one fungus failed to germinate. Of those that germinated, only Fusarium culmorum and the actinomycete were capable of continued growth and sporulation. Lysis or disintegration of the germ tubes of the others was noticed on the fourth day.

OVERWINTERING OF CERTAIN CEREAL PATHOGENS IN ALBERTA

1937 ◽  
Vol 15c (12) ◽  
pp. 547-559 ◽  
Author(s):  
W. R. Foster ◽  
A. W. Henry
Keyword(s):  
Winter Wheat ◽  
Fusarium Culmorum ◽  
Soil Surface ◽  
Freezing And Thawing ◽  
Tilletia Caries ◽  
Helminthosporium Sativum ◽  
Favorable Conditions ◽  
Germ Tubes ◽  
Continuous Freezing ◽  
Hardened Condition

Helminthosporium sativum, Fusarium culmorum, Ophiobolus graminis, Leptosphaeria herpotrichoides, Wojnowicia graminis, Erysiphe graminis, Tilletia caries, and Tilletia foetens readily overwinter under natural conditions at Edmonton, Alberta, Canada. The first five of these overwinter at Edmonton in both spore and vegetative stages and are highly resistant to cold. Even in a non-hardened condition several of them survived severe frost. Young germ tubes of H. sativum for instance continued growth after being frozen solid overnight. Fresh agar cultures of H. sativum, F. culmorum and O. graminis grew vigorously after exposure to sub-zero temperatures. Agar cultures of H. sativum and F. culmorum were viable after a 17-day exposure to temperatures ranging from about 0° F. to —50° F.Conidia of H. sativum proved less resistant to freezing and thawing than to continuous freezing. They survived longer than conidia of F. culmorum and F. graminearum. Mycelia of all foot-rot fungi grown on sterilized barley seeds were viable in one case after three months of continuous freezing, and in another after 40 alternate freezings and thawings. H. sativum and F. culmorum growing in soil survived 61 alternate freezings and thawings.H. sativum, F. culmorum and L. herpotrichoides, retained their viability more readily on the soil surface than when buried at depths of from 2 to 12 in. Well aerated soil seemed to favor the survival of H. sativum, although other factors besides aeration probably are involved. Strains of H. sativum from high latitudes were not better adapted to low temperatures than strains from lower latitudes.The bunt fungi, T. caries and T. foetens, are shown to be capable of overwintering at Edmonton in the form of mycelia in winter wheat. Infection of winter wheat from soil-borne spores may occur in western Canada, but in these experiments soil-borne spores did not survive to infect wheat in the spring.Erysiphe graminis overwinters in the perithecial stage at Edmonton. In the studies made, ascospores were differentiated in the spring, when favorable conditions prevailed and before the first infections of winter wheat were observed.

RELATIVE DECLINE OF OPHIOBOLUS GRAMINIS, HELMINTHOSPORIUM SATIVUM AND FUSARIUM CULMORUM IN THE SOIL

1960 ◽  
Vol 40 (2) ◽  
pp. 288-294 ◽  
Author(s):  
G. Semeniuk ◽  
A. W. Henry
Keyword(s):  
Fusarium Culmorum ◽  
Wheat Crop ◽  
Natural Soil ◽  
Large Measure ◽  
Wheat Seedlings ◽  
Helminthosporium Sativum ◽  
Loam Soil ◽  
Marked Decline ◽  
Relative Decline ◽  
Micro Organisms

The relative decline of three cereal root pathogens, Ophiobolus graminis Sacc., Helminthosporium sativum P. K. B., and Fusarium culmorum (W. G. Sm.) Sacc., in natural and sterilized black loam soil, was studied using inoculum grown in a sterilized soil-cornmeal medium. Since the severity of infection of wheat seedlings by the above fungi proved directly proportional to the amount of inoculum added to natural soil, it was used as a measure of the amount of effective inoculum in the soil at a given time. It was found by this means that inoculum of all three pathogens diminished greatly in amount in natural soil during the first few days following its addition, with that of O. graminis declining least, that of H. sativum more, and that of F. culmorum most. The decline rate was proportional to the amount of inoculum. After one week the decline had progressed further, but it was less for O. graminis than for the other two pathogens. In 3–4 weeks the amount of all three had reached a near-zero quantity. In sterilized soil the decline was similar to that in natural soil after the sterilized soil became recontaminated. However, that of F. culmorum was less pronounced here than in natural soil. Marked decline of O. graminis also occurred in natural soil supporting a seedling wheat crop. In large measure the decline studied appeared to be a quantitative degenerating process resulting from the activity of soil micro-organisms.

RECOVERY IN WHEAT FROM EARLY INFECTIONS BY HELMINTHOSPORIUM SATIVUM AND FUSARIUM CULMORUM

1959 ◽  
Vol 39 (2) ◽  
pp. 187-193 ◽  
Author(s):  
B. J. Sallans
Keyword(s):  
Fusarium Culmorum ◽  
Seedling Stage ◽  
Field Conditions ◽  
Partial Recovery ◽  
Helminthosporium Sativum ◽  
Early Seedling

The tendency of wheat plants to recover from initial stunting by Helminthosporium sativum and Fusarium culmorum was studied under field conditions by comparing areas of the successively formed leaves of the main culm. The yields of grain were taken as the over-all measure of the influence of disease on the plants.H. sativum when applied to seed caused significant reduction in areas of the first and second leaves of the seedlings. Successive leaves were progressively larger in relation to those of the uninoculated plants. The two varieties in the experiment were about equally stunted in the early seedling stage. Reward made a notable recovery as indicated by increased areas of the later leaves and a substantially greater yield of grain than in the controls. Thatcher made only a partial recovery and its yield of grain was slightly depressed.F. culmorum produced less stunting than H. sativum in seedling leaves, and recovery as indicated in the later leaves was less marked though significant.H. sativum and F. culmorum on the same plants caused more initial stunting of leaves followed by greater recovery than with either fungus alone.

STUDIES ON FOOT AND ROOT ROT OF WHEAT: IV. EFFECT OF CROP ROTATION AND CULTURAL PRACTICE ON THE RELATIVE PREVALENCE OF HELMINTHOSPORIUM SATIVUM AND FUSARIUM SPP. AS INDICATED BY ISOLATIONS FROM WHEAT PLANTS

1934 ◽  
Vol 10 (1) ◽  
pp. 115-124 ◽  
Author(s):  
W. C. Broadfoot
Keyword(s):  
Root Rot ◽  
Cultural Practices ◽  
Fusarium Culmorum ◽  
Cultural Practice ◽  
Root Tissue ◽  
Fusarium Spp ◽  
Crown Tissue ◽  
Helminthosporium Sativum ◽  
Relative Prevalence ◽  
Marked Tendency

The crown and root tissue from 43,305 of 47,360 plants examined in this investigation yielded Helminthosporium sativum, Fusarium culmorum and other Fusarium spp., either alone or in combination with these or other fungi and bacteria. It was the exception for any mature plant, the surface tissue of which was disinfected, to be free from fungi or bacteria. None of the various crop sequences or cultural practices used in this study appeared to significantly affect more than another the relative prevalence of either H. sativum or Fusarium spp., as indicated by isolations from the crown tissue of wheat. However, as there was a marked tendency at certain stations each year for H. sativum or Fusarium spp. to predominate, it was concluded that certain factors of the environment were more effective than the crop sequence in modifying the relative prevalence of the two fungi mentioned in the crown and root tissue of wheat plants.

AN ANTIBIOTIC-PRODUCING BACTERIUM OF THE GENUS PSEUDOMONAS

1954 ◽  
Vol 1 (2) ◽  
pp. 118-124 ◽  
Author(s):  
S. H. F. Chinn
Keyword(s):  
Pure Culture ◽  
Fusarium Culmorum ◽  
Antibiotic Activity ◽  
In Vitro Studies ◽  
Gram Positive ◽  
Gram Negative ◽  
Helminthosporium Sativum ◽  
Pathogenic Organisms

A Gram-negative rod, conforming; to Pseudomonas viscosa (Frankland and Frankland) Migula, was isolated in practically pure culture from a sample of wheat that did not show the usual mixture of epiphytes. In vitro studies revealed an unusual antibiotic spectrum against a variety of Gram-positive and -negative bacteria as well as against Helminthosporium sativum and Fusarium culmorum. Comparative.studies of the organism and P. aeruginosa, P. fluorescens, and P. chlororaphis indicated that it possessed greater antibiotic activity than any of these three species of Pseudomonas. Application to the control of some plant pathogenic organisms is suggested.

Behavior of zoospores of Phytophthora megasperma var. sojae and P. drechsleri in soil

1972 ◽  
Vol 50 (11) ◽  
pp. 2125-2130 ◽  
Author(s):  
R. S. Mehrotra
Keyword(s):  
Fluorescence Microscope ◽  
Natural Soil ◽  
Moderate Degree ◽  
Percentage Germination ◽  
Phytophthora Megasperma ◽  
Potential Capacity ◽  
Perfusion Apparatus ◽  
Phytophthora Drechsleri ◽  
Germ Tubes ◽  
Modified Soil

Experiments done with the modified soil perfusion apparatus indicate the potential capacity of the zoospores and cysts of Phytophthora drechsleri and P. megasperma var. sojae as inoculum units in soil. The results indicate that although zoospores/cysts do not retain infectivity for months, those of P. drechsleri do not lose it very rapidly. Experiments done to find out the period of motility of zoospores have shown that some zoospores of P. drechsleri and P. megasperma var. sojae remained motile for up to 30 and 24 h respectively. Saprophytic behavior of the two species of Phytophthora has been studied with the help of a fluorescence microscope and using a fluorescent dye. Cysts of P. drechsleri and P. megasperma var. sojae germinate to a moderate degree in natural non-amended soil. Germination ranged from 30 to 50% in the case of P. drechsleri and 15 to 25% in P. megasperma var. sojae. Amending the soil with 0.4% glucose, 0.4% asparagine increased the percentage germination of cysts in natural soil. Germ tubes of a small percentage of cysts in the two species terminate in miniature sporangia-like structures.

CYTOLOGICAL STUDIES OF HELMINTHOSPORIUM SATIVUM

1956 ◽  
Vol 34 (3) ◽  
pp. 321-327 ◽  
Author(s):  
S. B. Hrushovetz
Keyword(s):  
Helminthosporium Sativum ◽  
Germ Tubes

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.

STUDIES ON FOOT AND ROOT ROT OF WHEAT: I. EFFECT OF AGE OF THE WHEAT PLANT UPON THE DEVELOPMENT OF FOOT AND ROOT ROT

1933 ◽  
Vol 8 (5) ◽  
pp. 483-491 ◽  
Author(s):  
W. C. Broadfoot
Keyword(s):  
Root Rot ◽  
Fusarium Culmorum ◽  
Wheat Plant ◽  
Seedling Stage ◽  
Critical Studies ◽  
Helminthosporium Sativum ◽  
Unsterilized Soil ◽  
Micro Organisms ◽  
Effect Of Age ◽  
Made In

Studies were made to determine whether, in sterilized inoculated soil, Marquis wheat plants became more or less susceptible during the post-seedling stage to Ophiobolus graminis, Helminthosporium sativum, and Fusarium culmorum. While it was found that the plants in the seedling stage were more susceptible than at later stages, there was, with the technique used, no evidence that the plants become more or less susceptible during the post-seedling stage. The reasons for indefinite evidence on this important question are given. In sterilized soil, in open pot culture, inoculum of O. graminis was definitely more virulent when alone than when mixed singly or in combination with H. sativum, F. culmorum or Leptosphaeria herpotrichoides. The virulence of all pathogenes mentioned decreased progressively in sterilized soil, the greatest decrease taking place during the first 40 days, after which they were only slightly pathogenic and at the end of 120 days inoculum of O. graminis was impotent. The virulence of inoculum when added to unsterilized soil was greatly reduced in contrast with that in sterilized soil, and after 10 days it was practically at a minimum. These results emphasize the necessity of protecting inoculated sterilized soil against contamination by other micro-organisms in critical studies made in soil. They also throw light on the much recognized difficulty of producing foot rot in the field by prepared inoculum added to such soil.

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