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.

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.

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.

STUDIES ON THE CONTROL OF ROOT-ROT DISEASES OF CEREALS: IV. INFLUENCE OF MECHANICAL SEED INJURY ON INFECTION BY FUSARIUM CULMORUM IN WHEAT

1936 ◽  
Vol 14c (12) ◽  
pp. 438-444 ◽  
Author(s):  
J. E. Machacek ◽  
F. J. Greaney
Keyword(s):  
Root Rot ◽  
Field Experiments ◽  
Fusarium Culmorum ◽  
Western Canada ◽  
Wheat Seed ◽  
Fusarium Root Rot ◽  
Field Plots ◽  
Made In ◽  
Experimentally Induced

The results of field experiments made in 1932, 1933, and 1934, to determine the effect of mechanical seed injury on the incidence of root rot caused by Fusarium culmorum and on yield in wheat are presented.Successful positive attacks of Fusarium root rot were experimentally induced in field plots. The tests showed that reduced emergence, increased root rot, and reduced yield uniformly followed the planting of injured wheat seed; and that the amount of disease increased and the yield decreased with an increase in the degree of seed injury. In these experiments Mindum and Marquis wheat seemed equally affected by seed injury.The investigation suggests that the large annual losses in yield caused by root-rot diseases of cereals in Western Canada may be substantially reduced by sowing clean, vigorous, sound seed.

A study of factors influencing the genetics of reaction of barley to root rot caused by Helminthosporium sativum

1969 ◽  
Vol 47 (3) ◽  
pp. 429-443 ◽  
Author(s):  
E. Cohen ◽  
S. B. Helgason ◽  
W. C. McDonald
Keyword(s):  
Root Rot ◽  
Seed Weight ◽  
Field Resistance ◽  
Controlled Environment ◽  
Drastic Reduction ◽  
Similar Nature ◽  
High Positive Correlation ◽  
Polygenic Inheritance ◽  
Helminthosporium Sativum ◽  
Made In

The inheritance of seedling reaction to root rot, caused by the 514 isolate of Helminthosporium sativum, was studied in crosses and backcrosses among the barley varieties CI.8969 and CI.8873, which show resistance, and the variety Olli, which is susceptible. The study was carried out under a controlled environment in growth cabinets. The data from reaction tests of F3 and backcross families were analyzed by Elston's procedure for testing a one-locus hypothesis, and by Powers' partitioning method. Polygenic inheritance for seedling reaction was indicated, but subsequent experiments showed that seed weight strongly influenced the reaction, which could account for the polygenic interpretation. Based on a drastic reduction of resistance in greenhouse-produced seed, irrespective of seed weight, a high positive correlation of seed weight with resistance in field-produced seed, and other evidence of a similar nature, it was assumed that resistance was related to a principle, present in the seed or on the seed surface, the quantity of which was influenced by seed size and modified by environment. Whether there was a genotypic influence on the quantity of the resistance principle, aside from that affecting seed weight, was not established conclusively. A field study involving the same materials, made in an area known to produce natural root-rot infection, showed that no correlation existed between the disease indices of the entries in the seedling stage in the growth-cabinet tests, and their reaction to the disease in the field. CI.8873 showed field resistance, whereas CI.8969 did not.

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.

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.

OCCURRENCE AND SPORULATION OF HELMINTHOSPORIUM SATIVUM P.K.B. IN THE SOIL

1931 ◽  
Vol 5 (4) ◽  
pp. 407-413 ◽  
Author(s):  
A. W. Henry
Keyword(s):  
Microscopic Examination ◽  
Soil Types ◽  
Direct Microscopic Examination ◽  
Field Soils ◽  
Helminthosporium Sativum ◽  
Unsterilized Soil ◽  
Micro Organisms

Helminthosporium sativum, one of the most prevalent fungous pathogenes affecting the roots and other parts of wheat and related grass plants, grows and fruits readily as a saprophyte on various substrata. It might therefore be expected that it would be found in abundance in the soil. Attempts to isolate it directly from field soils by plating have been successful, but only in a small percentage of the trials. Failures are apparently largely attributable to the fact that this fungus does not sporulate commonly in ordinary field soils. This has been shown by direct microscopic examination of the soil and by artificial cultures. From a study of the latter it has been found that H. sativum will sporulate quite readily on several different soil types including sand if they are sterilized, but not if they are not sterilized.The fact that soils capable of supporting sporulation of this fungus may be rendered ineffective by adding small amounts of unsterilized soil, suggests that sporulation is inhibited by the saprophytic micro-organisms of the soil. It would appear that if H. sativum occurs in the soil, it must be present chiefly in the form of mycelium. Inability to form spores probably lessens the capability of this fungus to survive as well as to multiply in the soil.

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.

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