SOME FACTORS AFFECTING THE VIRULENCE OF ARTIFICIAL INOCULUM OF HELMINTHOSPORIUM SATIVUM P. K. AND B. AND OF FUSARIUM CULMORUM (W. G. SM.) SACC.

1941 ◽  
Vol 19c (2) ◽  
pp. 42-48 ◽  
Author(s):  
L. E. Tyner
Keyword(s):  
Fusarium Culmorum ◽  
Corn Meal ◽  
Wheat Seedlings ◽  
Factors Affecting ◽  
Helminthosporium Sativum ◽  
Effect Of Age

Investigations were conducted on the virulence of inoculum of Helminthosporium sativum P. K. and B. and of Fusarium culmorum (W. G. Sm.) Sacc. as affected by the size of the vessel in which the inoculum was increased, the amount of corn meal present in the medium, and the period of incubation. Inoculum of either pathogen containing 12% corn meal caused more disease on wheat seedlings than that with 5%. H. sativum, 14 days old, was more virulent than after 21, 28, or 35 days' incubation, but in the case of F. culmorum, there was no definite tendency with respect to the effect of age. The size of container was unimportant if desiccation was avoided.

STUDIES ON FOOT AND ROOT ROT OF WHEAT: VII. SOME FACTORS AFFECTING THE HEALTH OF WHEAT SEEDLINGS IN NUTRIENT SOLUTIONS

1943 ◽  
Vol 21c (1) ◽  
pp. 18-25 ◽  
Author(s):  
L. E. Tyner ◽  
W. C. Broadfoot
Keyword(s):  
Nutrient Solution ◽  
Root Rot ◽  
Fusarium Culmorum ◽  
Hydrogen Ion ◽  
Soil Culture ◽  
Wheat Seedlings ◽  
Factors Affecting ◽  
Ion Concentrations ◽  
Helminthosporium Sativum ◽  
Nutrient Solutions

The effect of iron tartrate on the development of chlorosis in wheat seedlings in nutrient solutions, and also the effect of extracts of Helminthosporium sativum P. K. & B. and Fusarium culmorum W. G. Sm. on disease expression, were studied under greenhouse conditions. Iron tartrate was effective in preventing chlorosis. Less iron was required in summer plantings than in winter plantings. Also, less iron was required in solutions with the higher hydrogen ion concentrations. Under the conditions employed, manganese effected no amelioration of chlorotic symptoms in the presence of a deficiency of iron.Sterilized and unsterilized filtered extracts of the pathogens mentioned added to crocks of the nutrient solution inhibited the growth of wheat seedlings, an effect in soil culture which is interpreted as an index of pathogenicity.

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.

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.

ON THE PREVALENCE OF PATHOGENIC FORMS OF HELMINTHOSPORIUM SATIVUM AND FUSARIUM CULMORUM IN THE SOIL OF WHEAT FIELDS AND ITS RELATION TO THE ROOT ROT PROBLEM

1934 ◽  
Vol 10 (3) ◽  
pp. 264-274 ◽  
Author(s):  
G. B. Sanford ◽  
W. C. Broadfoot
Keyword(s):  
Root Rot ◽  
Fusarium Culmorum ◽  
Black Soil ◽  
Seedling Stage ◽  
Infested Soil ◽  
Wheat Seedlings ◽  
Virulent Strains ◽  
Crown Tissue ◽  
Helminthosporium Sativum ◽  
Pot Culture

A total of 227 isolates of Helminthosporium sativum and 286 of Fusarium sp. (culmorum type) were obtained from the diseased crown tissue of wheat stubble in five fields located in the black soil belt of central Alberta, and an attempt was made to determine their relative virulence on wheat seedlings and on mature plants. The experiment was carried out under greenhouse conditions, with a range of soil temperature. Sterilized, artificially infested soil in open pot culture was used. The results indicated that the Helminthosporium isolates were as a rule moderately to weakly pathogenic, and that most of the Fusarium isolates were only weakly pathogenic to wheat plants in the seedling stage. Some isolates of each pathogen exhibited extreme virulence, but judging from the results on seedling plants, virulent strains were rather rare in the fields studied. On mature plants both fungi showed about equal degrees of virulence, which was on the whole weak, and the results were not considered significant for the purpose of the study. More isolates of the greater degrees of virulence were obtained from certain fields than from others. In view of the great susceptibility of seedling plants in sterilized re-infested soil and the variable results, presumably caused by association effects of contaminants of the soil in open pot culture, it was concluded that the object of the study could not be attained by means of data based on the seedling stage, or by the technique employed. The possibility of significant results being secured in sterilized re-infested soil, protected from contamination, and based only on mature plants, is discussed in relation to the root rot problem.

STUDIES ON FOOT- AND ROOT-ROT OF WHEAT: VI. METHODS OF SECURING INFECTION OF WHEAT SEEDLINGS FOR STUDY IN NUTRIENT SOLUTIONS

1938 ◽  
Vol 16c (6) ◽  
pp. 253-261 ◽  
Author(s):  
W. C. Broadfoot ◽  
L. E. Tyner
Keyword(s):  
Nutrient Solution ◽  
Fusarium Culmorum ◽  
Spore Suspension ◽  
Hypodermic Needle ◽  
Culture Solution ◽  
Wheat Seedlings ◽  
Nutrient Culture ◽  
Entire Plant ◽  
Helminthosporium Sativum ◽  
Nutrient Solutions

The two foot-rot diseases of wheat caused by Helminthosporium sativum P. K. & B. and Fusarium culmorum W. G. Sm. were studied in nutrient culture solutions instead of in the usual substrates of soil or sand. The most satisfactory results were obtained by first germinating the grains in a specially designed tray, then securing infection of the young plants by adding inoculum to the tray, after which the seedlings were transplanted to the nutrient culture solution. Infection of the seedlings was distinctly increased when sucrose was added to a nutrient solution infested previous to the time of transplantation. Infection was less satisfactory when the seed was immersed in a spore suspension, dried, and germinated on the tray. Very unsatisfactory infection was secured by adding a spore suspension in water, with or without sugar, to the nutrient solution at the time of transplanting the seedlings. Inoculating the seedlings with a spore suspension by means of a hypodermic needle produced practically no infection. Length of shoot, and particularly the dry and the green weight of the entire plant were reliable quantitative criteria for the evaluation of disease. The first method indicated appears to offer several important advantages in that the degree of infection can be controlled.

THE EFFECT OF CROP DEBRIS ON THE PATHOGENICITY OF CEREAL ROOT-ROTTING FUNGI

1940 ◽  
Vol 18c (7) ◽  
pp. 289-306 ◽  
Author(s):  
L. E. Tyner
Keyword(s):  
Plant Pathogens ◽  
Fusarium Culmorum ◽  
Barley Straw ◽  
Seedling Vigour ◽  
Wheat Seedlings ◽  
Helminthosporium Sativum ◽  
Nitrogen Ratio ◽  
Oat Straw ◽  
Micro Organisms ◽  
Cereal Root

The effect of wheat, oat, and barley straw, composted with soil, on the development of disease on the basal parts of wheat seedlings was studied in a series of greenhouse experiments during three seasons. The pathogens used were Ophiobolus graminis Sacc., Helminthosporium sativum P. K. and B., and Fusarium culmorum (W. G. Sm.) Sacc. The wheat-straw composts were distinctly more favourable to the development of disease than the composts of either oat or barley straw. The least injury occurred on seedlings grown in composts of oat straw. It is suggested that the micro-organisms associated with the decomposition of oat straw bring about some degree of biological control of the plant pathogens also present.Although the amount of straw applied sometimes influenced severity of disease, the effects were not consistent from planting to planting. Apparently the actual carbon to nitrogen ratio had less effect upon disease development than did the chemical nature of the straw.The kind and amount of straw in the composts also influenced seedling vigour. This vigour was, in general, inversely proportional to the degree of infection.The introduction of a short fallow period between plantings decreased infection somewhat and increased vigour.The pathogenicity of the artificial inoculum added at the first planting was practically vitiated before the second planting. Subsequently, the infection ratings tended to increase and were about the same as those in the uninoculated series.

STUDIES ON THE SEEDLING DISEASE OF BARLEY CAUSED BY HELMINTHOSPORIUM SATIVUM P.K. & B.

1956 ◽  
Vol 34 (4) ◽  
pp. 653-673 ◽  
Author(s):  
R. A. Ludwig ◽  
R. V. Clark ◽  
J. B. Julien ◽  
D. B. Robinson
Keyword(s):  
Disease Incidence ◽  
Infested Soil ◽  
Disease Development ◽  
Toxic Activity ◽  
Factors Affecting ◽  
Seedling Disease ◽  
Nutrient Salt ◽  
Helminthosporium Sativum ◽  
Treatment Comparisons

A standard sand – cornmeal – nutrient salt medium, for use in the production of artificial inoculum of Helminthosporium sativum, is described. This inoculum induces uniform plant disease development when thoroughly incorporated with the planting soil. The results presented clearly demonstrate the necessity of using a series of infestation levels in studies of factors affecting disease development in artificially infested soil. It is shown that considerable reliance can be placed on treatment comparisons within an experiment but that comparisons between experiments are much less accurate. The role of a toxin (or toxins) in disease development in barley seedlings has been demonstrated. The toxic activity was found to be distinct from that frequently encountered on addition of organic matter to soil. Results obtained suggest that toxin adsorption by the soil may play an important role in reducing disease incidence and severity.

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.

Sign in / Sign up

Export Citation Format

Share Document