The role of organic vs. conventional farming practice, soil management and preceding crop on the incidence of stem-base pathogens on wheat

2012

Abstract:Winter cereals (wheat, triticale, rye, barley) grown in experimental fields were assessed for sharp eyespot. Preceding crops (spring cereals and fallow) and weed control (herbicides application, no control) were taken into account. The health status evaluation was carried out at the stem elongation phase and at the milk maturity stage. The macroscopic estimation was accompanied by the analysis of fungal species identified on stem bases and roots, which showed various disease symptoms. The analysis of fungal species from the genus Rhizoctonia were especially noted. Mycological analysis of roots was carried out at the seedling growth and stem elongation phase, and stem bases at the seedling growth and milk maturity stage. Infection caused by Rhizoctonia spp. was confirmed by polymeraze chain reaction (PCR) assay. The highest infection was noted on wheat followed by triticale, rye and barley.Occurrence of sharp eyespot depended more on weed control than on what the preceding crop had been. At the milk maturity stage, lower severity of sharp eyespot of triticale, rye and barley was noted on plots not treated with herbicides, and on wheat with herbicide application. The research showed a significant effect of the preceding crop only on the health status of wheat. At the milk maturity stage, the highest infection was noted after spring triticale and the lowest after oats. Stems of cereals with sharp eyespot symptoms and healthy stems were settled mainly by Rhizoctonia cerealis (wheat -25.6%, triticale -12.0%, rye -22.2%, barley -11.3%), rarely by R. solani (respectively 6.0, 4.0, 2.9 and 1.8%). Rhizoctonia solani was isolated more often from roots with true eyespot and Fusarium foot rot symptoms. It may suggest that R. cerealis was the main causal agent of sharp eyespot on all tested cereals. The preceding crop did not affect the composition of Rhizoctonia species.

Section: Discussionmentioning

confidence: 73%

The Role of the Preceding Crop and Weed Control in the Transmission of Rhizoctonia Cerealis and R. Solani to Winter Cereals

2012

“…The reaction PCR with the use of primers ITS1/GMRS-3 also confirmed the occurrence of R. solani on 5 fields, giving the expected product of amplification 550 bp long. Applying specific primers type SCAR, Turner et al (2001) and Matusinsky (2008) also confirmed the presence of R. cerealis and R. solani in plant tissues of cereals. Nicholson and Parry (1996) found the presence of R. cerealis on single cereal stems, despite a lack of symptoms, however, clear disease symptoms did not always confirm the occurrence of that pathogen.…”

Section: Resultsmentioning

confidence: 83%

“…There was noted no significant variation depending on the previous crop and the fungicide protection applied (Tables 6, 7). Matusinsky et al (2008), using the PCR method, did not observe any variation in the intensity of occurrence of R. cerealis in wheat grown after different previous crops either. According to Żółtańska (2006), the infection by that pathogen is enhanced by cultivating cereals after cereals.…”

Section: Resultsmentioning

confidence: 99%

Occurrence of Sharp Eyespot in Spring Cereals Grown in Some Regions of Poland

2010

Occurrence of sharp eyespot was determined in the period 2006-2008, on commercial fields of spring cereals, localized in northern and central Poland. Percent of infected stems, and the disease index were evaluated. Occurrence of sharp eyespot on spring cereals, especially on oat, was low. Slight infection was mostly observed. In some farm fields, disease symptoms were not observed.A significant difference in the occurrence of sharp eyespot on barley in respective years was noted. On commercial farms, the effect of previous crop and fungicidal treatment on occurrence of sharp eyespot was not observed. Significant variation of the infection was noted only for barley. Presence of Rhizoctonia cerealis and R. solani in the damaged tissues was confirmed by mycological analysis as well as PCR assay.

“…Studies have mostly concerned susceptibility of wheat or rice (Bateman et al 2000;Li et al 2011;Liu et al 2011). Nicholson et al (2002), Ray et al (2004) and Matusinsky et al (2008) found differences in DNA concentrations of R. cerealis which had colonized different cultivars of wheat. Since observations were not repeatable for different years and localities of experimentation, it was concluded that sharp eyespot intensity did not depend entirely on cultivar (Bateman et al 2000;Nicholson et al 2002;Ray et al 2004).…”

Section: Discussionmentioning

confidence: 99%

“…R. cerealis can, however, also be isolated from asymptomatic plants (Lemańczyk 2012a). Nicholson and Parry (1996) and Matusinsky et al (2008) reported the poor correlation of results obtained by two techniques applied for assessment of sharp eyespot on field plants, i.e. classical, based on visual identification of symptoms, and molecular, using DNA amplification by PCR to identify the pathogen.…”

Section: Discussionmentioning

confidence: 99%

Susceptibility of winter Triticale Cultivars to Rhizoctonia Cerealis (sharp eyespot) and R. Solani

2012

Abstract:In the field study period from 2006 to 2010, the incidence and severity of sharp eyespot caused by Rhizoctonia were recorded on 36 cultivars of triticale at the milk ripe growth stage. Four localities in north-central Poland were included: Chrząstowo, Dębina, Kończewice and Minikowo. The susceptibility of the seedlings of 30 cultivars of triticale to R. cerealis (AG-D subgroup I) and R. solani (AG-5) was studied in the laboratory. There was much variation in incidence and severity of sharp eyespot between years and locations. The disease was most intense at Chrząstowo. At this location, the mean percentage of diseased stems on 28 cultivars was Most symptoms developed on coleoptiles, with less symptoms on the leaves and the least on the roots. There was much variation in susceptibility of triticale cultivars to both Rhizoctonia species. Cultivars were grouped into six categories according to the intensity of seedling infection. Categories 1, 2 and 3, representing low, moderate and high susceptibility to R. cerealis, included 17, 10 and 3 cultivars, respectively. Categories 4, 5 and 6, representing low, moderate and high susceptibility to R. solani, included 3, 12 and 15 cultivars, respectively. Cultivars Baltiko and Zorro had low, and cv. Cultivo had high susceptibility to both Rhizoctonia species. No cultivar was resistant to Rhizoctonia. There was a positive correlation between infection by R. cerealis and R. solani. Infection of coleoptiles by R. cerealis or R. solani was significantly correlated with infection of leaves. No correlation between intensity of sharp eyespot on triticale plants in the field and on seedlings in controlled conditions was found.