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

Abstract

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.

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

“…Infection of triticale by R. cerealis usually results in a less severe disease display than on wheat (Kurowski 2002;Lemańczyk 2012a). The disease may also occur only locally on triticale.…”

“…There are records of failure to isolate R. cerealis from typical symptoms of sharp eyespot. It was concluded that, in such cases, R. cerealis was probably suppressed by fast-growing saprotrophs present in rotting stems and dominating on agar isolation media (Lemańczyk 2012a). R. cerealis is a cereal-specific pathogen.…”

“…and numerous saprotrophs in vitro (Lemańczyk and Sadowski 2002;Kwaśna et al 2010). 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.…”

“…One hundred plants were collected at random along a diagonal transect across each of four plots (11 m x 1.5 m each) (only one plot at Minikowo) located at similar intervals along a diagonal transect across each field. Disease on sampled plants was assessed from symptoms on leaf sheaths and stems of each main shoot and tiller, according to a 0-4 severity scale (Lemańczyk 2012a). The percentage of diseased stems in each score category was recorded.…”

Auftreten und Schadwirkung von Rhizoctonia im deutschen Winterweizenanbau

“…Dabei wird im Anbau die Kulturart Winterweizen den weniger anspruchsvollen Kulturen wie Wintergerste oder Roggen vorgezogen und infolge auch auf weniger geeigneten Flächen angebaut (Ahlemeyer und Friedt, 2010). Ein leichter Boden mit Sandanteil erleichtert es dem bodenbürtigen Erreger (Gill et al, 2000;Bockus et al, 2010), Einleitung 10 ein vitales Inokulum im Boden aufzubauen (Lemańczyk, 2012). Förderlich ist zudem eine frühe Aussaat im Herbst in Kombination mit trockenen warmen Wetterbedingungen (Lemańczyk, 2012).…”