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.

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.

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.

Effects of cultivation on Rhizoctonia root rot, cereal cyst nematode, common root rot and yield of wheat in the Victorian Mallee

1991 ◽  
Vol 31 (3) ◽  
pp. 367 ◽  
Author(s):  
RFde Boer ◽  
JF Kollmorgen ◽  
BJ Macauley ◽  
PR Franz ◽  
Boer RF De
Keyword(s):  
Grain Yield ◽  
Root Rot ◽  
Dry Weight ◽  
Cyst Nematode ◽  
Cereal Cyst Nematode ◽  
Common Root ◽  
Common Root Rot ◽  
Root Diseases ◽  
Rhizoctonia Root Rot ◽  
Direct Drilling

The effects of method, time and number of cultivations on root diseases and yield of wheat were studied in a field experiment, in 1985, on a calcareous sandy loam in the Victorian Mallee. The incidence and severity of rhizoctonia root rot (Rhizoctonia solani) were higher in direct-drilled wheat than in wheat sown after cultivation. Compared with direct drilling, the severity of rhizoctonia root rot in seedlings was reduced by 40% with cultivation 20 weeks before sowing; by 70% with cultivation 1 day before sowing; and by 90% with 2 cultivations, the first at 16 weeks and the second 1 day before sowing. Cultivation generally increased the incidence of common root rot (Bipolaris sorokiniana) but had no significant effects on the severity of damage by the cereal cyst nematode (Heterodera avenae) or the number of nematode cysts produced, compared with direct drilling. The incidence and severity of root diseases, and the number of H. avenae cysts produced, were not significantly different in wheat sown after rotary hoeing than in wheat sown after scarifying. The severity of damage by H. avenae, the number of nematode cysts and the incidence of common root rot were higher (45, 70 and 36%, respectively) when scarifying was done 1 day before sowing, compared with scarifying 20 weeks earlier. Differences in sowing depth probably caused this effect since seed was sown deeper (as indicated by subcrown internode lengths) and plant emergence was less in the latter treatment. The timing and number of cultivations with a rotary hoe, however, did not significantly affect the severity of damage by H. avenae, the number of nematode cysts or the incidence of common root rot. The incidence of common root rot was correlated (r = 0.71) with the subcrown internode lengths, indicating that the deeper the seed was sown the greater the proportion of plants with the disease. Dry weight of seedlings and grain yield were negatively correlated (r = -0.79 and -0.66) with the severity of damage caused by H. avenae. Plant dry weight and grain yield were, however, not correlated with the severity of rhizoctonia root rot or the incidence of common root rot.

The transfer and characterization of resistance to common root rot from Thinopyrum ponticum to wheat

Genome ◽  
2004 ◽  
Vol 47 (1) ◽  
pp. 215-223 ◽  
Author(s):  
Hongjie Li ◽  
Robert L Conner ◽  
Qin Chen ◽  
Haiyan Li ◽  
André Laroche ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Root Rot ◽  
Triticum Aestivum L ◽  
Genomic In Situ Hybridization ◽  
Cochliobolus Sativus ◽  
Common Root ◽  
Thinopyrum Ponticum ◽  
Common Root Rot ◽  
Kernel Color

Common root rot, caused by Cochliobolus sativus (Ito and Kurib) Drechs. ex Dastur, is a major soil-borne disease of spring and winter wheat (Triticum aestivum L. em Thell.) on the Canadian prairies. Resistance to common root rot from Thinopyrum ponticum (Podp.) Liu and Wang was transferred into wheat via crossing with Agrotana, a resistant wheat – Th. ponticum partial amphiploid line. Evaluation of common root rot reactions showed that selected advanced lines with blue kernel color derived from a wheat × Agrotana cross expressed more resistance than the susceptible T. aestivum 'Chinese Spring' parent and other susceptible wheat check cultivars. Cytological examination revealed 41 to 44 chromosomes in the advanced lines. Genomic in situ hybridization, using total genomic DNA from Pseudoroegneria strigosa (M. Bieb) A. Löve (St genome) as a probe, demonstrated that the blue kernel plants had two pairs of spontaneously translocated J–Js and Js–J chromosomes derived from the J and Js genome of Th. ponticum. The presence of these translocated chromosomes was associated with increased resistance of wheat to common root rot. The lines with blue aleurone color always had a subcentromeric Js–J translocated chromosome. The subtelocentric J–Js translocated chromosome was not responsible for the blue kernel color. The genomic in situ hybridization analysis on meiosis revealed that the two spontaneous translocations were not reciprocal translocations.Key words: Cochliobolus sativus, genomic in situ hybridization, blue kernel color.

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