Natural senescence of the root cortex of spring wheat in relation to susceptibility to common root rot (Cochliobolus sativus) and growth of a free-living nitrogen-fixing bacterium

1982 ◽  
Vol 66 (1) ◽  
pp. 13-20 ◽  
Author(s):  
J. W. Deacon ◽  
S. J. Lewis
Keyword(s):  
Spring Wheat ◽  
Root Rot ◽  
Cochliobolus Sativus ◽  
Nitrogen Fixing ◽  
Common Root ◽  
Free Living ◽  
Root Cortex ◽  
Common Root Rot

The effect of soil salinity on common root rot of spring wheat and barley

1993 ◽  
Vol 73 (1) ◽  
pp. 323-330 ◽  
Author(s):  
L. J. Duczek
Keyword(s):  
Spring Wheat ◽  
Soil Salinity ◽  
Root Rot ◽  
Salinity Gradient ◽  
Cochliobolus Sativus ◽  
Liquid Media ◽  
Common Root ◽  
Inoculum Level ◽  
Common Root Rot ◽  
The Relationship

Samples were taken from several sites across a salinity gradient from areas where plants were visibly unaffected to the edge of saline areas where no plants grew, from commercial fields located near Saskatoon in 1984, 1987, 1990 and 1991. There was a significant (P = 0.05) positive correlation for wheat and barley between salinity and common root rot in all years, except 1991 (1984: r = 0.445, n = 26; 1987: r = 0.390, n = 54; 1990: r = 0.244, n = 75; 1991: r = 0.247, n = 40). The correlation between inoculum level and disease was not significant, except for one barley field in 1990. However, when inoculum level was used as a covariate, the significance of the relationship between salinity and common root rot increased. Growth of Cochliobolus sativus was unaffected on solid and liquid media until conductivity levels were higher than 30–50 mmhos cm−1. Since wheat and barley do not grow at levels higher than 10–15 mmhos cm−1, salinity would have a greater affect on plants than on the pathogen. The relationship between salinity and disease is consistent with the theory that stress increases common root rot in plants. However, the variation in salinity only explains about 20% of the variation in common root rot. Key words: Cochliobolus sativus, common root rot, salinity, cereals

scholarly journals Response of wheat root pathogens to crop management in eastern Saskatchewan

2007 ◽  
Vol 87 (4) ◽  
pp. 953-963 ◽  
Author(s):  
M. R. Fernandez ◽  
P. Basnyat ◽  
R. P. Zentner
Keyword(s):  
Spring Wheat ◽  
Root Rot ◽  
Soil Tillage ◽  
Cochliobolus Sativus ◽  
Oilseed Crop ◽  
Relative Role ◽  
Common Root ◽  
Common Root Rot ◽  
Previous Crop ◽  
Tillage System

A survey of common root rot in spring wheat (Triticum aestivum L.) and durum wheat (T. turgidum L. var. durum) crops was conducted in eastern Saskatchewan from 1999 to 2001 to investigate the association of agronomic practices with disease and fungal populations, in particular Fusarium species associated with Fusarium head blight (FHB), which is a disease of increasing importance in this region. Spring wheat preceded by summerfallow, or grown after a sequence that included summerfallow and a cereal crop, had increased levels of Cochliobolus sativus and lower levels of most Fusarium spp. in discoloured subcrown internodes. Cropping sequences that included at least one noncereal crop in the previous 2 yr resulted in higher percentage isolations of F. avenaceum and F. graminearum than sequences which did not include noncereal crops. Highest levels of F. avenaceum, the most common FHB pathogen in the province, were observed when the previous crop was a pulse. Tillage system effects depended on the previous crop. When wheat was preceded by an oilseed crop, C. sativus decreased as the number of tillage operations decreased, whereas F. avenaceum and M icrodochium bolleyi increased with a reduction in tillage. Associations of fungal isolations with previous glyphosate use were negative for C. sativus and positive for F. avenaceum and M. bolleyi, although these effects varied depending on tillage system. Increased levels of important Fusarium pathogens were thus associated with current trends in production practices, namely continuously cropped diversified rotations and less reliance on mechanical soil tillage. Further investigation into the relative role of tillage intensity and glyphosate use versus cropping sequence on Fusarium populations in underground wheat tissue is needed. Key words: Common root rot, wheat, Cochliobolus sativus, Fusarium, tillage, glyphosate, crop rotation, nitrogen

INHERITANCE OF THATCHER-TYPE RESISTANCE TO COMMON ROOT ROT IN SPRING WHEAT

1968 ◽  
Vol 48 (5) ◽  
pp. 479-486 ◽  
Author(s):  
Hugh McKenzie ◽  
T. G. Atkinson
Keyword(s):  
Triticum Aestivum ◽  
Spring Wheat ◽  
Root Rot ◽  
Recessive Gene ◽  
Cochliobolus Sativus ◽  
Common Root ◽  
Wheat Stem Sawfly ◽  
Common Root Rot ◽  
Resistant Varieties ◽  
Stem Solidness

Inheritance of reaction to common root rot, caused chiefly by Cochliobolus sativus, was studied in F3 populations of wheat, Triticum aestivum, from crosses between the root-rot-resistant, hollow-stemmed varieties, Thatcher and Pembina, and the moderately root-rot-susceptible, solid-stemmed variety, CT 733. The results indicated that the resistance of Thatcher and Pembina, which appear to have the same gene complement, is controlled by a major recessive gene and one or two minor genes.No association was found between inheritance of root-rot reaction and the inheritance of stem solidness which determines resistance to the wheat stem sawfly (Cephus cinctus). Therefore, there should be no difficulty in incorporating root-rot resistance into sawfly-resistant varieties.

The impact of crop rotation and N fertilizer on common root rot of spring wheat in the Brown soil zone of western Canada

2005 ◽  
Vol 85 (3) ◽  
pp. 569-575 ◽  
Author(s):  
M. R. Fernandez ◽  
R. P. Zentner
Keyword(s):  
Fusarium Head Blight ◽  
Crop Rotation ◽  
Spring Wheat ◽  
Root Rot ◽  
Triticum Aestivum L ◽  
Cochliobolus Sativus ◽  
Common Root ◽  
Head Blight ◽  
Common Root Rot ◽  
The Impact

From 2000 to 2003, spring wheat (Triticum aestivum L.) grown in southwest Saskatchewan 1 or 2 yr after summerfallow, and after lentil (Lens culinaris Medik), flax (Linum usitatissimum L.), or continuously with and without fertilizer N was examined for root rot by measuring discoloration of subcrown internodes. Discolored tissue was also plated on nutrient agar for fungal identification. In general, common root rot was present at consistently highest levels in wheat grown after lentil, and at lowest levels in wheat grown continuously with low N fertility. The most common fungal species isolated from affected subcrown internodes were Cochliobolus sativus (Ito and Kurib.) Drechs. ex Dast. and Fusarium spp. Among the latter, F. avenaceum (Fr.) Sacc., F. equiseti (Corda) Sacc. and F. pseudograminearum O’Donnell & T. Aoki were most frequent. Fusarium avenaceum is one of the most common fusarium head blight pathogens in Saskatchewan. Wheat after lentil had one of the highest levels of this fungus. Continuous wheat grown with recommended N rates and wheat grown after summerfallow had in most cases similar root rot levels, but the frequency of fungi differed. Among the crop rotations examined, it appears that the most favourable for development of root rot in wheat was a wheat-lentil rotation. This cereal-pulse system may also contribute to a build-up of F. avenaceum inoculum for the development of fusarium head blight, an important emerging disease of cereals in Saskatchewan. Key words: Crop rotation, common root rot, wheat, Cochliobolus sativus, Fusarium, nitrogen

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.

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