Further sources of resistance to common root rot (Cochliobolus sativus) of wheat

1974 ◽  
Vol 14 (70) ◽  
pp. 666 ◽  
Author(s):  
GB Wildermuth
Keyword(s):  
Bread Wheat ◽  
Root Rot ◽  
First Record ◽  
Cochliobolus Sativus ◽  
Wheat Cultivars ◽  
Common Root ◽  
Sources Of Resistance ◽  
Common Root Rot ◽  
High Level

One cultivar of einkhorn, one cultivar of emmer, three cultivars of durum and 43 cultivars of bread wheat were screened for resistance to common root rot (Cochliobolus sativus). The emmer cultivar, Yaroslav and the white-grained bread wheat cultivars, Festival and Mexico 120, showed a high level of resistance. This is the first record of resistance in white-grained cultivars and the advantage of using whitegrained rather than red-grained cultivars as sources of resistance in Australia is indicated. It is considered that the major source of resistance in Festival, Gamut and Spica has been derived from Pusa cultivars.

RESISTANCE IN WHEAT TO COCHLIOBOLUS SATIVUS, A CAUSE OF COMMON ROOT ROT

1965 ◽  
Vol 45 (4) ◽  
pp. 343-351 ◽  
Author(s):  
B. J. Sallans ◽  
R. D. Tinline
Keyword(s):  
Root Rot ◽  
Practical Method ◽  
Cochliobolus Sativus ◽  
Common Root ◽  
Fusarium Spp ◽  
Natural Field ◽  
Common Root Rot ◽  
Record Data ◽  
Disease Rating ◽  
High Level

Resistance in wheat to Cochliobolus sativus, the main cause of common root rot in cereals, was shown to be a heritable character. Crosses were made between Thatcher, McMurachy, Willet, 492 (P.I. 94562-1), and 182 (PI. 4309), all of which have shown some resistance to C. sativus but can become heavily infected. The crosses gave rise to both highly resistant and highly susceptible lines that were consistent in their root-rot reaction at four or five locations over 2 years. A simple, practical method was evolved to determine the root-rot reactions of lines and it was basic to their selection. It relies upon natural field infections and is oriented to obtain a high level of disease of the plants. The pedigree method of plant breeding was used to overcome the problem posed by the tendency for many plants to escape infection. Isolations of organisms from lesions gave assurance that the observed resistance was for C. sativus and not for Fusarium spp., which may also cause common root rot. A simplified disease rating was used to record data on the basis of two classes, essentially, resistant and susceptible.

Inoculum density of Cochliobolus sativus in soil and common root rot of wheat cultivars in Queensland

1988 ◽  
Vol 39 (4) ◽  
pp. 569 ◽  
Author(s):  
RD Tinline ◽  
GB Wildermuth ◽  
DT Spurr
Keyword(s):  
Root Rot ◽  
Dry Weight ◽  
Threshold Level ◽  
Inoculum Density ◽  
Cochliobolus Sativus ◽  
Wheat Cultivars ◽  
Common Root ◽  
Common Root Rot ◽  
High Inoculum ◽  
Seeding Time

Common root rot was assessed in wheat cultivars grown at field sites in Queensland having low, intermediate and high inoculum densities of Cochliobolus sativus. The densities at seeding time in the upper 10 cm of the profile, were 3, 77 and 132 viable propagules per g soil respectively. Both incidence and intensity of disease at tillering, flowering and firm dough stages of plant development appeared closely related to inoculum density. Additional inoculum applied with seed increased disease markedly at the low inoculum density site and slightly at the intermediate site, and had no effect at the high inoculum density site, indicating a threshold level for maximum disease in the test. Reduction in dry weight of plants at the low and high sites paralleled the disease levels at the tillering and flowering stages. The relative reactions of the cultivars were expressed consistently: Songlen and Timgalen invariably were more diseased than Kite and QT2338/9. The results suggest that cultivars may be evaluated for resistance in the field from tillering onward if disease levels are adequate. C. sativus was the dominant fungus isolated from the subcrown internodes of plants from non-inoculated subplots. Its frequency of isolation was much less from the low inoculum density site than the intermediate and high inoculum density sites, and lower from Kite and QT2338/9 than from Songlen and Timgalen. Fursariurn chlamydosporum was isolated from subcrown internodes with increasing frequency as the season progressed. However, it was considered to be a secondary invader of the plant material.

The epidemiology of common root rot in Manitou wheat: disease progression during the growing season

1974 ◽  
Vol 52 (7) ◽  
pp. 1757-1764 ◽  
Author(s):  
P. R. Verma ◽  
R. A. A. Morrall ◽  
R. D. Tinline
Keyword(s):  
Triticum Aestivum ◽  
Disease Severity ◽  
Plant Development ◽  
Root Rot ◽  
Growing Season ◽  
Cochliobolus Sativus ◽  
Infection Rates ◽  
Common Root ◽  
Common Root Rot ◽  
Disease Rating

Common root rot in Triticum aestivum cultivar Manitou caused primarily by Cochliobolus sativus was followed during plant development in 1969, 1970, and 1971 at Matador, Saskatchewan. Plants were sampled at intervals, and three variables based mainly on the occurrence of lesions on subcrown internodes were studied: number of diseased plants per square meter; percentage of diseased plants; and disease rating which integrated percentage of diseased plants and disease severity on each plant. All variables increased with time, and the progression curves in all 3 years were hyperbolic, indicating that the increases were like those of a simple interest disease as described by Van der Plank. In two of the years, almost 100% of the plants were diseased considerably before the end of the season. The transformation proposed by Van der Plank for simple interest diseases, log10[1/(1 − x)], was applied to the percentages of diseased plants, and regressions were calculated. The slopes of these lines (infection rates) were as follows: 1969, 0.99% plants per day; 1970, 1.32%; and 1971, 1.96%. In 1969 the onset of disease was later than in 1970 and 1971, and there was correspondingly less disease at the end of the growing season.

EFFECTS OF IMAZALIL SEED TREATMENT ON SUBCROWN INTERNODE LENGTHS AND COLEOPTILE-NODE-TILLERING IN WHEAT

1980 ◽  
Vol 60 (4) ◽  
pp. 1467-1472 ◽  
Author(s):  
S. H. F. CHINN ◽  
P. R. VERMA ◽  
D. T. SPURR
Keyword(s):  
Spring Wheat ◽  
Root Rot ◽  
Seed Treatment ◽  
Cold Hardiness ◽  
Morphological Changes ◽  
Wheat Cultivars ◽  
Soft Or ◽  
Common Root ◽  
Common Root Rot ◽  
Treated Seed

The effects of seed treatment with imazalil at 0.2 and 0.3 g a.i./kg seed on subcrown internode length and occurrence of coleoptile-node-tillers (CNT) was studied in four spring wheat cultivars at two locations in Saskatchewan. Without treatment, Cypress had the longest internodes followed in descending order by Glenlea, Neepawa, and Wascana. Generally, plants from imazalil-treated seed had significantly shorter subcrown internodes. Only a few plants from nontreated seed produced CNT and of these, many were soft or aborted, while the treated seed produced a number of CNT and many of these were firm tillers. The possible importance of these morphological changes in the reduction of common root rot, on drought resistance, cold hardiness, and yield is discussed.

The effect of common root rot on components of grain yield in Manitou wheat

1976 ◽  
Vol 54 (24) ◽  
pp. 2888-2892 ◽  
Author(s):  
P. R. Verma ◽  
R. A. A. Morrall ◽  
R. D. Tinline
Keyword(s):  
Triticum Aestivum ◽  
Grain Yield ◽  
Disease Severity ◽  
Root Rot ◽  
Major Effect ◽  
Kernel Weight ◽  
The Other ◽  
Cochliobolus Sativus ◽  
Common Root ◽  
Common Root Rot

The effects of common root rot (Cochliobolus sativus) on components of grain yield in naturally infected Triticum aestivum cultivar Manitou were studied at Matador, Saskatchewan, by sampling plants at maturity in 1969, 1970, and 1971. Plants were sorted into severe (SE), moderate (MO), slight (SL), and clean (CL) categories based mainly on the extent of lesions on the subcrown internodes. The number of tillers per plant, the number and weight of grains per head, the weight per head, and the 1000-kernel weight in each category were determined. Increasing values of all five components were consistently associated with decreasing disease severity. SE was mostly significantly different from the other three categories in all components except 1000-kernel weight; differences between SL and MO were usually non-significant. CL and SL were mostly significantly different for the number of tillers per plant and weight per head but non-significant for the weight and number of grains per head and 1000-kernel weight. Apparently, the major effect of common root rot was to reduce the number of tillers per plant and number of grains per head.

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