Severity Of Common Root Rot Research Articles

Identification of Fungal Species Associated with Crown and Root Rots of Wheat and Evaluation of Plant Reactions to the Pathogens in North Dakota

Common root rot (CRR) and crown rot (CR), caused by Bipolaris sorokiniana and Fusarium species, respectively, can cause significant yield losses in cereal crops. To assess the prevalence, incidence, and severity of these diseases in North Dakota, wheat samples were collected from spring wheat fields across the state in 2012, 2013, and 2014. Based on sub-crown internode symptoms, a greater incidence and severity of CRR was observed in 2012 (warm and dry year) than in 2013 and 2014. Also, the Northwestern Glaciated Plains and Northwestern Great Plains ecoregions showed greater CRR incidence and severity compared to the Northern Glaciated Plains and Lake Agassiz Plains ecoregions in the state. Bipolaris sorokiniana and Fusarium species including F. acuminatum, F. avenaceum, F. culmorum, F. graminearum, F. equiseti, F. pseudograminearum, F. oxysporum, F. redolens, F. sporotrichioides, and F. solani were isolated and identified from the root and crown tissues of the wheat samples. B. sorokiniana was isolated more frequently than other fungal species in all sampled years and ecoregions of North Dakota. F. acuminatum, F. avenaceum, F. culmorum, F. equiseti, F. graminearum, F. pseudograminearum, and F. redolens were pathogenic causing infections on seedlings of the two wheat genotypes (ND652 and Alsen), whereas isolates of F. oxysporum and F. solani were non-pathogenic and considered as secondary invaders associated with the root and crown rot diseases. Evaluation of some spring wheat genotypes for reactions to one B. sorokiniana isolate at seedling and adult plant stages, and one F. culmorum isolate at the seedling stage indicated that susceptibility to these pathogens varied among different wheat genotypes tested. This study provides useful information on fungal species associated with root and crown rots of wheat in North Dakota and on resistant/susceptible reactions of some spring wheat lines to the different fungal isolates evaluated.

The In-Silico Development of DNA Markers for Breeding of Spring Barley Varieties That Are Resistant to Spot Blotch in Russia

The fungal pathogen Cochliobolus sativus Drechs. Ex Dastur, anamorph Bipolaris sorokiniana (Sacc.) Shoemaker is one of the most common barley pathogens worldwide and causes spot blotch and root rot in barley. Spot blotch is considered to be the major biotic stress hampering the commercial production of barley. During high disease severity, which occurs in the northwestern region of Russia once every three to four years, yield losses for barley may reach 40%. An increase in common root rot severity results in yield losses that can reach 80%. The goal of the current study was to identify significant markers that can be employed as diagnostic DNA markers to breed C. sativus pathogen-resistant varieties of barley. In 94 spring barley cultivars and lines, the resistance of seedlings and adult plants to the impact of C. sativus on their leaves and roots was investigated. Five genomic regions associated with resistance to Spot blotch were identified (on chromosome 1H (50–61.2 cM), 2H (68.7–69.68 cM), 3H (18.72–26.18 cM), 7H (7.52–15.44 cM)). No significant loci were determined to be associated with root rot. According to obtained data, 11 significant SNPs were converted into KASP markers and 6 markers located on chromosome 3H were determined to possess good accuracy and the potential to be employed in marker-assisted selection.

Screening of barley breeding lines for resistance to common root rot disease through incidence and severity parameters

Cochliobolus sativus, the causal agent of common root rot (CRR), is a devastating fungal pathogen of barley that can cause significant yield losses worldwide. The development of resistant cultivars has proven difficult, therefore, in this work, CRR-resistant barley germplasm was developed by crossing three resistant-by-susceptible cultivars currently used in Europe and West Asia. Following greenhouse evaluations of 150 doubled haploid lines derived from these crosses, 40 lines were evaluated under artificial infection conditions using incidence and severity parameters during two consecutive seasons. Data showed significant differences among barley lines with a continuum of resistance levels ranging from highly susceptible to resistant which were consistent in both seasons. However, five promising lines had slightly lower CRR disease than the others. Additionally, significant differences (P <0.05) in mean incidence and severity values were found among lines, with values being consistently higher in the susceptible ones. However, CRR severity increased linearly as incidence increased in both seasons. All together, the present study suggests that, the newly identified resistance lines can serve as potential donors for ongoing CRR resistance breeding program to generate high-yielding commercial barley cultivars, and that the positive correlation between CRR parameters I and S may be beneficial for many types of studies on this disease.

A simple approach to assess common root rot severity incidence data in wheat

Common root rot (CRR) of wheat, caused by Cochliobolus sativus, produces discoloration of the subcrown internodes (SCIs) and is directly related to yield losses. It is critical to clearly define and standardize the CRR assessment methods to avoid subjectivity and variability between assessors. Therefore, in this study, a comparison between the incidence (I; proportion of diseased SCIs) and the severity (S; proportion of SCI showing CRR symptoms) was investigated to explore the possibility of simplifying disease rating. Assessments were made visually at multiple sample sites in artificially- and naturally-inoculated research and production fields for three growing seasons. Significant differences (P = 0.001) in mean I and S values were found among cultivars, with values being consistently higher in the susceptible ones. However, CRR severity increased linearly as incidence increased in both Triticum durum and T. aestivum wheat. Their slopes and intercepts of the I–S relationship were consistent over the three growing seasons. This result may be considered a significant contribution for CRR assessment in wheat breeding programs.

Root rot severity and fungal populations in spring common, durum and spelt wheat, and Kamut grown under organic management in western Canada

Fernandez, M. R., Fox, S. L., Hucl, P., Singh, A. K. and Stevenson, F. C. 2014. Root rot severity and fungal populations in spring common, durum and spelt wheat, and Kamut grown under organic management in western Canada. Can. J. Plant Sci. 94: 937–946. A 3-yr field study (2010 to 2012) was conducted in the Brown soil zone of southwest Saskatchewan to determine the reactions of common, durum and spelt wheat cultivars currently registered in western Canada, and of Kamut wheat, to common root rot (CRR) under organic management. The genotypes selected for this study are often grown by organic producers in this region. Over the 3 yr of this study, Cochliobolus sativus, the main causal agent of CRR, was the fungus most frequently isolated from discoloured subcrown internodes, followed by Fusarium spp. The latter constituted an overall total of over 19% of all isolations and consisted of at least 12 different species, the most frequently detected of which were F. equiseti, F. avenaceum, F. acuminatum and F. oxysporum. The relative prevalence of the most commonly isolated genera/species agrees most closely with previous studies conducted under organic management. In general, C. sativus was less common in Kamut than in durum and spelt wheat, and it was more frequently isolated from durum than common wheat. In contrast, there were few differences in the isolation of Fusarium spp. among wheat species. Their isolation was greater for common wheat and Kamut than for durum wheat. For all 3 yr, the greatest mean CRR severity was observed in spelt wheat, followed by durum wheat and Kamut, with common wheat having the lowest average severity. For individual cultivars, the durum wheat AC Avonlea, Kyle and Transcend had the greatest CRR severity of all cultivars in this species and CDC Verona the lowest. Common wheat cultivars AC Elsa, CDC Kernen and Red Fife had the greatest CRR severity and Superb and Unity the lowest severity within their species. Under organic conditions, avoiding growing cultivars with high susceptibility to CRR is recommended given the expected presence of this disease in most fields and environments.

A simple method for assessing severity of common root rot on barley.

Common root rot caused by Cochliobolus sativus is a serious disease of barley. A simple and reliable method for assessing this disease would enhance our capacity in identifying resistance sources and developing resistant barley cultivars. In searching for such a method, a conidial suspension of C. sativus was dropped onto sterilized elongated subcrown internodes and incubated in sandwich filter paper using polyethylene transparent envelopes. Initial disease symptoms were easily detected after 48h of inoculation. Highly significant correlation coefficients were found in each experiment (A, B and C) between sandwich filter paper and seedling assays, indicating that this testing procedure was reliable. The method presented facilitates a rapid pre-selection under uniform conditions which is of importance from a breeder’s point of view.

Sustaining productivity of a Vertosol at Warra, Queensland, with fertilisers, no-tillage or legumes. 9. Production and nitrogen benefits from mixed grass and legume pastures in rotation with wheat

Reduced supplies of nitrogen (N) in many soils of southern Queensland that were cropped exhaustively with cereals over many decades have been the focus of much research to avoid declines in profitability and sustainability of farming systems. A 45-month period of mixed grass (purple pigeon grass, Setaria incrassata Stapf; Rhodes grass, Chloris gayana Kunth.) and legume (lucerne, Medicago sativa L.; annual medics, M. scutellata L. Mill. and M. truncatula Gaertn.) pasture was one of several options that were compared at a fertility-depleted Vertosol at Warra, southern Queensland, to improve grain yields or increase grain protein concentration of subsequent wheat crops. Objectives of the study were to measure the productivity of a mixed grass and legume pasture grown over 45 months (cut and removed over 36 months) and its effects on yield and protein concentrations of the following wheat crops. Pasture production (DM t/ha) and aboveground plant N yield (kg/ha) for grass, legume (including a small amount of weeds) and total components of pasture responded linearly to total rainfall over the duration of each of 3 pastures sown in 1986, 1987 and 1988. Averaged over the 3 pastures, each 100 mm of rainfall resulted in 0.52 t/ha of grass, 0.44 t/ha of legume and 0.97 t/ha of total pasture DM, there being little variation between the 3 pastures. Aboveground plant N yield of the 3 pastures ranged from 17.2 to 20.5 kg/ha per 100 mm rainfall. Aboveground legume N in response to total rainfall was similar (10.6–13.2 kg/ha per 100 mm rainfall) across the 3 pastures in spite of very different populations of legumes and grasses at establishment. Aboveground grass N yield was 5.2–7.0 kg/ha per 100 mm rainfall. In most wheat crops following pasture, wheat yields were similar to that of unfertilised wheat except in 1990 and 1994, when grain yields were significantly higher but similar to that for continuous wheat fertilised with 75 kg N/ha. In contrast, grain protein concentrations of most wheat crops following pasture responded positively, being substantially higher than unfertilised wheat but similar to that of wheat fertilised with 75 kg N/ha. Grain protein averaged over all years of assay was increased by 25–40% compared with that of unfertilised wheat. Stored water supplies after pasture were <134 mm (<55% of plant available water capacity); for most assay crops water storages were 67–110 mm, an equivalent wet soil depth of only 0.3–0.45 m. Thus, the crop assays of pasture benefits were limited by low water supply to wheat crops. Moreover, the severity of common root rot in wheat crop was not reduced by pasture–wheat rotation.

Effect of Organic Amendments on Soilborne and Foliar Diseases in Field-Grown Snap Bean and Cucumber.

Several paper mills in Wisconsin have programs for spreading paper mill residuals (PMR) on land. A growing number of vegetable farmers recognize the agronomic benefits of PMR applications, but there have been no investigations on the use of PMR for control of vegetable crop diseases. Our objective was to determine the effect of PMR amendments on soilborne and foliar diseases of cucumber and snap bean grown on a sandy soil. Raw PMR, PMR composted without bulking agent (PMRC), or PMR composted with bark (PMRBC) were applied annually in a 3-year rotation of potato, snap bean, and pickling cucumber. Several naturally occurring diseases were evaluated in the field, along with in situ field bioassays. All amendments suppressed cucumber damping-off and Pythium blight and foliar brown spot of snap bean. Both composts reduced the incidence of angular leaf spot in cucumber. In a separate field experiment planted with snap bean for two consecutive years, all amendments reduced common root rot severity in the second year. In a greenhouse experiment, the high rate of PMRBC suppressed anthracnose of snap bean. These results suggest that the application of raw and composted PMR to sandy soils has the potential to control several soilborne and foliar diseases.

Relationship Among Seed Size, Planting Date, and Common Root Rot in Hard Red Winter Wheat.

A dryland field study was conducted to determine the effect of seed size and planting date of hard red winter wheat on the severity of common root rot caused by Bipolaris sorokiniana (Sacc.) Shoemaker. Seed of cvs. Hawk, TAM 200, TAM 107, Scout 66, and Siouxland 89 were separated into three size categories of small, mixed, and large and were planted in the first weeks of September and October 1994 and 1995. Disease ratings for incidence and severity of subcrown internode infections were made in March and at harvest. At harvest, grain yields were collected. In both years of the study, there was no interaction between seed size and cultivars for any of the measured variables. Overall, seed size had no effect on disease severity or grain yield for either year. However, when sorted by planting date, plants from small seed yielded less than plants from other seed. October plantings showed lower disease indices than September plantings at the March evaluation. At the harvest disease evaluation, there were no differences in disease severity between planting dates for the first year but, in the second year of the study, plants from the October planting had lower disease than those from the September planting. There was no significant correlation among seed size, final yield, and disease index. The results of this study suggest that the expense of planting higher-quality certified seed cannot be justified for producing hard red winter wheat in dryland conditions in the Texas Panhandle, considering the current price of wheat and the average dryland yield.

Crown rot and common root rot in wheat grown under different tillage and stubble treatments in southern Queensland, Australia

In southern Queensland, crown rot caused by Fusarium graminearum Group 1 and common root rot caused by Bipolaris sorokiniana are common soilborne diseases of wheat and barley. The incidence of these diseases was measured in the susceptible wheat ( Triticum aestivum L.) cultivar, Hartog which was grown under no tillage, reduced tillage (two tillage operations plus herbicides) and where stubble was retained or removed by burning (1984–1986) or physically removed (1987–1993). Primary tillage was with blade, disc or chisel implements. The level of crown rot and common root rot was higher where stubble was retained than where it was removed. There was a significant interaction in incidence of crown rot between stubble management and some types of tillage. Where there was no tillage, incidence of crown rot was significantly higher where stubble was retained (32.2%) than where it was removed (4.7%) whereas under disc tillage, there was no significant difference in disease level between stubble treatments (12–17%). Incidence of crown rot was not affected by the type of tillage employed. The incidence of deadheads (heads without grain) caused by crown rot was lowest in the no tillage plots (4.3%) and highest in the reduced (19.3%) and conventional (12.2%) disc tillage stubble retained treatments. Available soil water (depth of 1.2 m) at sowing and anthesis was lowest in the conventional disc stubble retained plots and highest in the no tillage stubble retained plots. It is hypothesised that the high levels of deadheads were due to moderate to high levels of disease and low available soil water at planting and anthesis. Although incidence of crown rot was high under no tillage, incidence of deadheads was lower than in other treatments due to the higher availability of soil water. Severity of common root rot was lower in stubble removed, than in stubble retained, treatments and also lower in no tillage than in any of the other tillage treatments.

Oat residue and soil compaction influences on common root rot (Aphanomyes euteiches) of peas in a fine-textured soil

Management of common root rot (Aphanomyces euteiches Drechs.) in peas (Pisum sativum L.) is sought primarily by host crop avoidance for several years. Soil compaction is known to aggravate A. euteiches disease in peas but effects on infection and subsequent symptom development are not sufficiently known to assist in cultural control. Several isolated observations have noted that oat crop residues may suppress A. euteiches infection and disease in pea roots. The individual and combined influence (a factorial combination of two factors each at two levels) of a prior oat crop and soil compaction were studied for their effects on common root rot severity in processing peas grown in an A. euteiches disease nursery on a fine-textured soil in the northern Corn Belt of the USA. A previous crop of summer oats relative to prior-year peas significantly suppressed common root rot and increased pea fresh vine weight 210% at peak bloom stage. Both fresh vine weight and green pea yield were reduced as much as 63% by soil compaction and increased as much as 48% by a prior oat crop. Greater soil bulk density at the 10 to 25-cm depth identified wheel traffic compaction patterns in each year. A 10-fold reduction of saturated hydraulic conductivity in the 10 to 25-cm compacted zone and high soil-water potentials within the upper 60 cm both confirmed an impaired water drainage, especially during infiltration events. These observations support the use of a previous full season or summer oat crop jointly with chisel plowing, plus the prevention of excessive traffic during secondary tillage and planting, to reduce common root rot in a field infested with A. euteiches. Shallow incorporation of oat shoot and root residue by chiseling could be a crucial component of the cultural control of the disease. R Rodriguez Kabana Section editor

Effect of chloride fertilization on Bedford barley and Katepwa wheat

Recent studies in the northern Great Plains have confirmed that the chloride (Cl−) component of fertilizers can reduce disease severity and increase grain yield for wheat (Triticum aestivum) and barley (Hordeum vulgare). Field studies were conducted in Manitoba in 1989 and 1990 to determine the effect of rates of 25 and 50 kg Cl− ha−1 (applied as KCl or NaCl) applied with or without Cochliobolus sativus inoculum on plant nutrient status, disease severity and grain yield for Katepwa wheat and Bedford barley. Chloride application, regardless of placement or source, increased the Cl− concentration in plant tissue sampled at the boot to heading stages. Rates of 25 and 50 kg Cl− ha−1 resulted in significant reductions in the severity of common root rot for barley in two of six experiments and for wheat in one of four experiments. Chloride applications did not reduce spot blotch severity on barley in either of two experiments conducted. Inoculum did not have a consistent effect on any of the parameters measured. The application of 50 kg Cl− ha−1 significantly increased grain yield for barley by an average 393 kg ha−1 in two of eight experiments, but did not increase grain yield for wheat in any of eight experiments. Yield responses to Cl− were not related to soil Cl− content, Cl− concentration in plant tissue or observed reductions in disease. Key words: Chloride, fertilizers, barley, wheat, disease, yield

Penicillium bilaji and phosphorus fertilization effects on the growth, development, yield and common root rot severity of spring wheat

A strain ofPenicillium bilaji Chalabuda (PB) has recently been commercially released as a seed inoculant to increase phosphorus (P) uptake by wheat (Triticum aestivum L.). The purpose of this study was to compare the effects of drill applied P (15 kg P ha−1) with PB seed inoculation on early growth, development, P uptake, and grain yield of ‘Stoa’ spring wheat at four sites in North Dakota.

Effects of tillage systems and crop rotations on root and foliar diseases of wheat, flax, and peas in Saskatchewan

The dynamics of root and foliar diseases were studied in spring and winter wheat, peas, and flax and under zero, minimum, and conventional tillage at Indian Head, Saskatchewan, from 1987 to 1990. No disease was observed on flax during the 4 yr. Year-to-year variation was more important than tillage systems in explaining the incidence of bacterial leaf spot and foot rot of peas. Tan spot and septoria leaf blotch were the most important foliar diseases of wheat. Disease ratings (0–9) of the leaf spots were greater on winter wheat (average 2.2) than on spring wheat (average 1.9) and also greater on spring wheat following a cereal (average 2.0) than following peas or summer fallow (average 1.7). Hot and dry weather did not enhance development of foliar diseases, and no consistent effects of tillage on leaf disease ratings were observed. However, take-all and common root rot were affected by crop management. Incidence of take-all was greater on winter wheat (8%) than on spring wheat (1%) and also greater on winter wheat under conventional (11%) than minimum (8%) or zero tillage (6%). Severity of common root rot of spring wheat was greater following either spring (24%) or winter wheat (25%) than peas (22%) and summer fallow (15%). The severity of common root rot varied from year to year. In 3 of the 4 years, minimum-till and zero-till reduced the severity of the disease.Key words: Zero till, minimum till, conventional till, crop rotation, disease, spring wheat, winter wheat

Common Root Rot and Yield Responses in Spring Wheat From Chloride Application to Soil in Northwestern Minnesota

Plots were established at five locations in northwestern Minnesota during 1986-1989 and fertilized with five rates of chloride (0, 13, 27, 40, and 54 kg/ha) using two sources (CaCl 2 and KCl) to determine if Cl affected the incidence and severity of common root rot and grain yield. Locations differed for all variables measured, but there were no significant interactions (P=0.05) between the rate of Cl fertilization and location (.)

Effect of cropping history on soil populations of Bipolaris sorokiniana and common root rot of wheat

Six winter and four summer crops, two pasture legumes and two pasture grasses, were grown in rotation with wheat in soil naturally colonized with Bipolaris sorokiniana. Soil populations of B. sorokiniana under the different rotations were measured at the beginning of winter and of summer between 1982 and 1986. Populations increased under wheat, barley and triticale, remained static under oats, safflower and chickpea, and declined under buffel grass, cocksfoot, lucerne, mung bean, snail medic, sorghum, sunflower and White French millet. Populations also declined under a fallow, and propagules of the fungus were still present after 4 years. Where populations had declined owing to cropping history, they were effectively restored to their previous levels after one wheat crop. Severity of common root rot in wheat caused by B. sorokiniana, was reduced from that occurring with continuous wheat when wheat was planted after safflower, sorghum, mung bean, snail medic, lucerne and buffel grass. Disease levels in wheat following barley, triticale, oats, chickpea, millet, sunflower, cocksfoot or a fallow were not significantly different from that of continuous wheat. When a second wheat crop was planted, severity of common root rot was high in all treatments, irrespective of the previous cropping history. The implications of these findings in developing control strategies for common root rot by crop rotation are discussed.

The effects of fumigation, rotation with lupins, and nitrogen application on plant growth and common root rot of wheat at Geraldton, Western Australia

The effects of soil fumigation (98% methyl bromide + 2% chloropicrin at 580 kg/ha) and N fertilizer (0, 12.5, 25, 50 or 100 kg N/ha) were examined in field trials on continuous wheat and wheat in rotation with lupins on the Geraldton sandplain. Fumigation increased grain yields at N fertilizer levels more or =25 kg/ha and was associated with reduced incidence and severity of common root rot (Bipolaris sorokiniana)[Cochliobolus sativus]. Grain yield was not significantly affected by rotation. Fumigation increased soil ammonium levels and decreased soil nitrate levels. Rotation of wheat and lupins increased mid-season growth at all levels of applied N but only increased grain yield where no N was applied.

Effects of Tillage on Common Root Rot of Wheat in Texas

Effects of tillage on the incidence and severity of common root rot caused by Bipolaris sorokiniana and on spore distribution were studied in continuous wheat culture at three locations in Texas. Spore populations were determined to a depth of 40 cm in 10-cm increments. The majority of spores were found in the top 10 cm of soil regardless of tillage method. Although significantly more spores were found with conventional tillage than in the no-still system, the distribution of spores in the soil profile was not significantly affected by tillage (...)

Influence of continuous cropping on severity of common root rot in wheat and barley

Influence of continuous cropping on severity of common root rot in wheat and barley

Association of Bipolaris sorokiniana, Fusarium graminearum Group 2, and F. culmorum on Spring Wheat Differing in Severity of Common Root Rot

Isolation of B. sorokiniana from crowns of the same plants in classes 0, 1, 2, and 3 and from plants with no subcrown internodes did not differ significantly in each of the 3 yr and averaged 76%. Fusarium graminearum group 2 was recovered from 7% of the subcrown internodes and 9% of the crowns, whereas F. culmorum was isolated from 2% of the subcrown internodes and 4% of the crowns